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Multimedia Big Data Security
Navit Gaur
Fall 2015
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Abstract -- Multimedia big data is becoming more and
more important as the amount of data shared over the web
is increasing. With the rise of social networking sites like
Facebook, Vine, Instagram, Spotify, the amount of
multimedia data shared by the users is increasing
exponentially. As the data grows rapidly, complex security
issues arise.
This paper will focus on the challenges, issues and needs
that multimedia big data is facing in terms of security and
different approaches to overcome these issues. Multimedia
big data security frameworks, data encryption and
decryption algorithms will be analysed and compared.
1. Introduction to Multimedia Big Data Security
With the rise of digital technologies,it is possible nowadays to
make an exact copy of the source. Multimedia data is
represented as a bit of streams that can be saved on optical or
magnetic media. Since digital recording is a process in which
every part is read from source and then it is copied to a new
destination it is possible to create an exact replica of the
source media. Protection of multimedia big data is therefore a
crucial problem.
The essential security requirements for multimedia systems
are as follows:
· Confidentiality: Encryption can be used to prevent
unauthorized entities from getting secret information.
· Data integrity: Any changes in the data can be
discerned by using robust and fragile watermarking,
digital signatures and message authentication codes.
· Data origin authenticity: Proof of origin can be
verified using message authentication codes, digital
signatures and fragile and digital watermarking.
· Entity authenticity: Authentication protocols can be
used to ensure that the entities taking part in the
communication are the ones they claim to be.
· Non-repudiation: Non-repudiation mechanisms can
be used to prove whether a particular event or action
happened to any parties involved. The event or action
can be generation, sending, receipt or transport of a
message. Non-repudiation certificates, non-
repudiation tokens and protocols establish the
accountability of information.
Distributed multimedia applications can be secured using
authentication control mechanisms. However, it is not enough
to secure multimedia data broadcast. Multimedia data still
needs to be encrypted during transmission.
The next chapter provides a short introduction to encryption
techniques and watermarking techniques.
2. Understanding of Multimedia Big Data
Security[19][20][21]
This chapter explains how the security requirements
mentioned in the previous chapter can be obtained.
· Confidentiality: Cipher systems can be used to hide
information from unauthorized users. Private key and
public key encryption can be used to encrypt the data.
In streaming applications a large amount of data
needs to be sent from the sender to the receiver. One
of the problems of transmitting a huge amount of data
is that data can change due to transmission errors,
higher compression rates or scaling operations. If
common encryption methods are used then the
decryption of an encrypted block may fail because
the original data could not be retrieved if one of the
blocks is altered. A solution to these problems is to
use partial encryption i.e. encrypt only certain parts
of data instead of encrypting the whole data.
· Data Integrity: Data integrity can be checked using
one way has functions. Also some mechanisms
detailed in the next section to can be used to detect
any changes in the data. It is not possible to prevent
data manipulation using these mechanisms but they
make these manipulations detectable. A hash function
maps strings of random length to strings of fixed
length. Hash functions are public and hence can
anyone knowing the function can check the integrity
of data by calculating the hash value. As in
multimedia applications, data can alter because of
scaling or compression, it is not appropriate to apply
hash functions directly to media. Instead it should be
applied to the semantic data of the media stream.
· Data Origin Authenticity: Authentication codes,
digital signatures, fragile and robust digital
watermarks can be used to determine data origin
authenticity. These mechanisms can also be used to
maintain data integrity. All these mechanisms are
detection mechanisms and hence they cannot prevent
data manipulation but can allow to detect if there was
an alteration in data.
Digital signatures can be used to ensure authenticity
of multimedia data by using public key encryption
systems. Digital signatures should not be applied
directly to the multimedia data as the image
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processing techniques like conversion or scaling
maybe used on the multimedia data. Once these
operations are applied on the multimedia data it is
changes irreversibly. Although the content was not
changed the digital signature verification will fail.
Digital signatures should be used on the feature codes
of multimedia data that are not changed during
operations like scaling or compression.
In digital watermarking the multimedia data is
slightly modified and the verification data is
embedded in it rather than being appended to it.
Anyone with the proper secret key can use the
watermark to determine whether the data was altered
or not by checking the embedded information. The
problem with watermarking techniques is that it is
not possible to embed a large amount of data at a
higher rate for the verification.
· Entity Authenticity: Authentication protocols can be
used to ensure that the parties taking part in the
communication are indeed who they claim to be. One
of the simplest example of an authentication protocol
is the challenge response protocol in which the
verifier sends a randomly generated number to the
claimant. The claimant generates a value using the
challenge and a secret and returns it to the verifier.
The verifier can then check that the claimant has the
appropriate secret key.
· Non-repudiation: Non-repudiation mechanisms
based on public key and private key encryption
systems are used to provide security techniques that
can be used to link data and actions to their
originators. By making use of these mechanisms it is
possible to prove to the involved parties or third
parties whether a particular even or action occurred.
The event or action maybe creating a message,
transmitting a message or receiving a message
Cryptography is probably one of the most common
methods of protecting multimedia data. Secret key
encryption used the same key for encrypting and
decrypting data. It requires that the secret key be
exchanged between the sender and receiver before any
transmission takes place. Although the speed of secret key
encryption is acceptable the key needs to be exchanged in
advance and that is its weakness.
Public key encryption uses two keys. The key used for
encryption is different from the one that is used for
decryption. The public key is used for encryption and the
private key is used for decryption. Anyone can use the
public to encrypt the message but the only the user with
the private key can decrypt it. This method is more
convenient than the secret key method but the encryption
and decryption takes longer.
In digital watermarking the original data is modified and
additional information is embedded into it which are
undetectable during normal use but detectable by
computers and software. This additional information that
is embedded is called watermark.
Digital watermarking should match the following
requirements:
· The embedded watermark should be resilient
against any attacks performed by unauthorized
entities. The aimof such attacks is to gain access
to unwatermarked data by damaging or removing
the embedded watermark.
· The watermark embedded in the multimedia
data should not cause any visual or audible
changes in the data. The watermark should only
be detectable with the help of computers and
software.
It should be almost impossible to remove or extract the
embedded watermark from the data without appropriate access
to the secret key.
3. Multimedia Big Data Security Algorithms
This chapter will focus on security algorithms for multimedia
big data security. The algorithms will be classified and then
they will be reviewed thoroughly. In the last section of the
chapter, the algorithms will be compared.
3.1 A Classification of the Algorithms
3.1.1 Fast Encryption Method Based on New FFT
Representation
The fast encryption method is based on Fast Fourier
Transformation to secure sensitive information within
multimedia data. This method has dual key security feature,
since it’s not only the encryption key but the mapping or
transformation structure should be available to breach the
information or data.
3.1.2 Multimedia Big Data Sharing in Social Networks Using
Fingerprinting and Encryption in the JPEG2000
Compressed Domain
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The development of social interactive media, as exhibited by
person to person communication locales, for example,
Facebook and YouTube, consolidated with advances in mixed
media content investigation, underscores potential dangers for
vindictive utilize, for example, unlawful replicating, robbery,
written falsification, and misappropriation. Subsequently,
secure interactive media sharing and traitor tracing issues have
gotten to be basic and critical in social network. Hence this
algorithm is focused in securing social media data.
3.1.3 Scrambling
One of the easiest form of encryption that is used for securing
multimedia data is Scrambling. It uses encryption process that
performs random permutations using some specific pattern to
multimedia data. Image’s histogram remains the same, just the
individual positions are shuffled.
3.1.4 Post-Compression Encryption Algorithm
The Secure Real-time Transport Protocol, or the basic
approach encrypts the compressed bit stream by packetizing
the multimedia data and then encrypting every single packet
using AES. It is secure but it has a huge computational
overheads and also it is not conducive to different favourable
properties of the compressed bit streams in general, owing to
the encryption of compressed data.
3.1.5 Pre-Compression Encryption Algorithm
Pre-compression encryption implies encrypting uncompressed
or raw bits which will waste a lot of computational resources.
3.1.6 Selective Encryption
Transmitted pictures may have diverse applications, for
example, business, military and medicinal applications. So it is
important to scramble picture information before transmission
over the systemto save its security and anticipate unapproved
access. This Selective Encryption results in highly correlated
original and decrypted images. Hence is a good technique to
use.
3.1.7 Joint Video Compression and Encryption (JVCE)
Approaches
The principle thought behind joint coding is to incorporate
encryption into compression operation by parameterization of
the compression blocks, and not adjusting the compressed bits.
Entropy Coding and Wavelet Transform are the two main
compression blocks where this approach has been applied.
3.2 A Review of the Algorithms
3.2.1 Fast Encryption Method Based on New FFT
RepresentationThe FFT encryption method is based on
secrecy systems, which is also the set of transformations. The
algorithmic representation structure can be divided and
observed as follows:
(i) Splitting the Fast Fourier Transform into small sets
of transformation.
(ii) Decomposing the transformation using discrete
orthogonal transforms.
Fig. 1: Encryption method with dual key functionality.
Let us now understand the FFT encryption using Walsh-
Hadamard Transform (WHT).
• Sylvester matrix is the base of WHT.
• Hadamard functions form a set of orthogonal
functions having value -1 or +1 which means they
need only addition or subtraction for computation.
• WHT matrix can be represented as
H2
n = H2
n-1 H2
n-1
H2
n-1 -H2
n-1 where n=2,3
H1 = 1, H2 = 1 1
1 -1
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• We have initially added to the eight-point
recursive FFT in view of the Walsh-Hadamard
change. This mapping can be appeared by the
factorization as the accompanying:
F8 = [P8][B8
2][D8][B8
1][P8][B8
2]T∏(m=1 to 3){ I2
m-1 © H2 ©
I2
3-m } (2)
where [P8] is the row permutation matrix, which has the
format as the accompanying :
When k = 1 , 2 then we get [B8
1] and [B8
2] respectively as :
The iterative algorithm for deriving H8 matrix is:
H8 = ∏(m=1 to 3){ I2
m-1 © H2 © I2
3-m}
We also defined Diagonal Matrix as :
[D8] = diag{ 1,1,W3,3 , W4,4 , W5,5 , W6,6 , W7,7 , W8,8 }
= diag{ 1,1,2-1i, 2-21, -2-2i , -2-55.6569i , 2-55.6569}
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• Hence once we deduce the mapping structure our
next goal is sensitive data encryption.
Encryption equation for transformation is
represented as:
E8 = [P8][B8
2][S8][D8][B8
1][P8][B8
2]T ∏(m= 1 to3){ I2
m-1 ©
H2 © I2
3-m } (3)
Fig. 2: A flow diagram to represent FFT encryption based on
WHT.
Flow diagram depicts the encryption approach inside of the
transformation process. [x[O],x[l],...,x[7]j' is the info signal
appeared in figure Y, on the left hand side. Likewise,
[Y[o],Y[i],...,Y[7]]" is the yield, transformed signal. The
procedure is done as the accompanying; first we separate the
information picture into 8x8 pieces, and after that we encode
the touchy data by utilizing the eq. (3) by the accompanying
arrangement:
TBlock8 = [E8][Block8]ET
8]
After encryption, we converse change the recurrence segments
of the information back to spatial space, before transmitting it
in the public channel.
As seen fromthe figure 2, the shuffling is accomplished by :
As a matter of fact, the encryption demonstrated above, took
place at the end but it could have been done at the beginning.
Giving us an efficient encryption method which can change
the location of shuffling.
• Hence there is no constraint as in when to begin
or end shuffling process.
3.2.2 Multimedia Big Data Sharing in Social Networks Using
Fingerprinting and Encryption in the JPEG2000 Compressed
Domain
• This section presents implementation of Tree-
Structured Harr (TSH) transformation
homomorphically encrypted domain for
fingerprinting using social network analyses with
the aim of protecting social media data.
• Fingerprinting Technique basically embeds users
fingerprints into digital contents by making
changes in host signal in such a way that the
content remains the same.
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• JPEG 2000 Code Based TSH Transform :
The most commonly used signal processing tool
is DWT, wherein TSH is generic wavelet
transform.
The fingerprinting plan in the TSH transform of
the encrypted data empowers the proprietor to
install unique finger print sequence into media
content.
Fingerprints embedding is done in encrypted domain using
additive Homomorphic property in the selected embedded
positions.
Once the discrete TSH transform of the input image is
done the JPEG
2000 transformation is divided into 3 sections :
(i) Firstly quantize the wavelet transform
coefficients.
(ii) Divide the quantized coefficients into
different bit planes and code them
through several passes : at embedded
block coding with optimized
truncation(EBCOT) to give compressed
byte stream.
(iii) Lastly arrange the compressed byte
stream into separate wavelet packets.
Thus, it is possible to select bytes generated fromdifferent bit
planes of different resolutions for joint fingerprinting and
encryption for JPEG2000 image directly.
• Fingerprints Embedding Procedure :
To shield substance from unlawful redistribution
after they are legitimately got by client, interactive
media substance ought to be implanted into
exceptional client data (e.g., fingerprints) which
should be vague to the clients into every client's copy
for following unlawful clients.
Since the watermark-embedding procedure is
performed in the compressed and encrypted space .
For a compacted furthermore, scrambled JPEG2000
pictures, we implant the various hierarchical
fingerprints into the compressed and encrypted
various leveled subband of the TSH area.
Suppose Nu is a set of users. Choosing encrypted byte stream
in approximation subband to combine vector EX I = (ex1, ex2,
..., exI
L)
Choose another encrypted byte stream in all horizontal and
vertical subbands to combine different vectors, such as EXO =
(ex1, ex2, ..., exO
L) for different community code segment
embedding.
Here EX I and EXO is the length of codeword and
the user cpdeword encryption equations is :
EFXk = EXO
k + α ∗ Fk, k = 1, 2, ...,Nu
Where α is the scale factor and Fk is the fingerprint
information
for user k.
3.2.3 Scrambling
One of the easiest form of encryption that is used for securing
multimedia data is Scrambling. It uses encryption process that
performs random permutations using some specific pattern to
multimedia data. Image’s histogram remains the same, just the
individual positions are shuffled. The security that scrambling
alone provides is relatively less. It reduces the efficiency of
compression of video bit stream that leads to loss in
compression and size increase of the video file.
Scrambling is generally used as a simple way for encrypting
live analog/digital video signals such as surveillance camera
feeds where complex ciphers are eliminated because it causes
delay in computation. Some general scrambling techniques are
as follows:
1. Line Inversion Video scrambling: In this technique, whole
or some portions of the signal scan lines are simply inverted.
This method is comparatively cheap and easy to implement.
Its shortcoming is that it provides low security.

2. Sync Suppression Video scrambling: In this method, the
vertical/horizontal line syncs are either made invisible or are
completely deleted. This method provides a low-cost solution
for Encryption and it also provides a good quality of video
decoding. A common disadvantage is that the level of
ambiguity reached by this technique depends on the content of
video. 

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3. Line Shuffle Video scrambling: In this technique, every
signal line on the screen is rearranged. This scrambling
method provides bettersecurity but it needs a lot of storage for
re-ordering the screen. 

4. Cut and Rotate Video scrambling: In this technique, every
scan line is cut into parts and then combined in a permuted
manner. This scheme provides a compatible video signal,
gives an excellent amount of obscurity and good decode
quality and stability. However, it requires specialized
scrambling equipment. Compression algorithms have been
designed for the unscrambled signals and they use the
statistical characteristics of raw data. Once the signal is
scrambled, these characteristics will change and the
performance of the compression filter will be degraded.
In Zig-Zag permutation method, in the place of mapping 8 × 8
blocks (as in DCT compression stage in video coder) to 1 × 64
vector in Zig-Zag order, it maps individual 8 × 8 blocks on to
1 × 64 vector by using a random permutation list (secret key).
This method consists of three steps.
1. Generating a permutation list of cardinality 64.

2. Splitting the coefficients according to list of permutation.
3. Sending the outcome to entropy coding method.
But this method reduces the compression rate of video because
the random permutation deforms the probability distribution of
DCT (Discrete Cosine Transform) coefficients.
A scrambling scheme of digital image should have a
comparatively easy implementation, accommodating low
delay operation and low cost decoding for real time interactive
applications. It should be free fromcompression algorithmand
should not cause any loss for the compression operation. We
present here a case study of technique presented by Liu and
Zeng for understanding the scrambling in a better way. Figure
below contains an overview of that technique.
Fig. 3: Scrambling Scheme
Initially, the authors transform input signal into frequency
domain by using Discrete Cosine Transform (DCT) or
Discrete Wavelet Transform (DWT). Then the transform
coefficients are divided into further operations which permute
their values in the image. Motion vectors are matter of random
sign modifications and shuffling. Along with that, a
cryptographic key is used to manage scrambling. The motion
vectors and scrambled coefficients are then sent to
compression block for obtaining compressed bit stream. Users
who are authorized can easily obtain the original main content
back by using the same compression key. This scrambling
operation is executed before compression, thus it allows
preservation of properties of multimedia-specific compression
like scalability and transcoding. It is easy for frequency
domain scrambling to control the transparency (i.e., which
portion of the video will be allowed in free access).
Encryption/decryption methods are designed such that it
preserves the properties of image transformed that the entropy
coders are allowed to properly compress an image.
Apart from secure and easy transcoding, framework of joint
scrambling-compression provides many different advantages
over those that execute scrambling on the compressed bit
streams. Those advantages are:
1. Flexibility to encrypt selectively: In domain of frequency,
it’s very easy to recognise which data parts are crucial for
security. This permits to provide various levels of security and
transparency.
2. Encrypting incompressible segments: It’s simple to detect
which data parts are incompressible. For instance, coefficient
sign bits are generally hard to compress; but still those are
important for security purposes. This incompressible segment
of data is selected for scrambling without impacting the total
efficiency of compression. Data segments like motion vector
information are generally compressed without any loss. Hence
they can be selected to encrypt without the necessity of
considering the transcoding issue, since this doesn’t makes
sense for transcoder to recode the portion of compressed data.
The selected data can easily be located in the frequency
domain without causing any processing overhead. On the
other side, since the compressed bit stream is generally
variable length coded, it is usually difficult to perform fine
scale selective encryption on compressed bit stream without
causing bit overheads and processing. 

3.Low vulnerability to channel errors: Encrypting data after
compressing such as using AES over MPEG is more
vulnerable to channel errors because a block of 128 bits in
AES is bound together so that a single bit error in a block will
cause synchronization word/bits of that block to be erroneous.
It will be harder to recover from transmission errors in the
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network since the synchronization information is hidden in the
encrypted video stream. On the other hand, spatial scrambling
in frequency domain has no such adverse effect on the
resiliency of error. 

4.Compatibility to transform domain signal processing:
Scrambling consists of changing the spatial parts of individual
frequency coefficients. Watermarking and other transform
domain tasks can be easily performed without requiring a
cryptographic key. 
Some of the techniques for scrambling are
as follows: 

1. Selective Bit Scrambling: The basic method scrambles the
bits that are selected in transform coefficients for encrypting
the image. Each bit of coefficient can be one of the three
types. Significance bits for the coefficient are most significant
bit of the value 1, and any of the preceding bits of the value 0.
This constraints the magnitude of the coefficient to known
range. Remaining magnitude bits are refinement bits that are
used in refining the coefficient within a recognizable range.
Sign bit says if the range is negative or positive. 

2. Block Shuffling: In block shuffling, we divide every sub-
band into multiple similar sized blocks. The block size can be
different for various sub-bands. Within every sub-band,
coefficient blocks are shuffled according to the table of
shuffling which is generated using key. The table of shuffling
generally will be distinct for various sub-bands, and it can
differ for every frame. 

3. Block Rotation: Every coefficient block is rotated to form
encrypted blocks to improve security.
3.2.4 Post-compression Encryption Algorithm
The Secure Real-time Transport Protocol, or the basic
approach encrypts the compressed bit stream by packetizing
the multimedia data and then encrypting every single packet
using AES. It is secure but it has a huge computational
overheads and also it is not conducive to different favourable
properties of the compressed bit streams in general, owing to
the encryption of compressed data.
So many different algorithms have been proposed—which are
format compliant, or have low computational requirements.
Gadgegast and Meyer suggested a selective video encryption
scheme called Secure MPEG or SECMPEG for the MPEG-1
video coding standard. See figure below for details.
Fig. 4: Different levels of security offered by the SECMPEG
algorithm (Meyer and Gadgegast).
It offers various levels of security by encoding different parts
of compressed bit stream:
Algorithm 1: This encrypts headers from layer of sequence to
layer of slice. 

Algorithm 2: Along with that, it encrypts DCT coefficients of
low frequency of each block in I-frames. 

Algorithm 3: This encrypts complete I-frames and I-blocks in
the B- and P-frames. 

Algorithm 4: This encrypts complete MPEG-1 sequence with
the basic process. 

The approach has some notable limitations: Computations
savings are not so significant because I-frames constitute
30%–60% of a MPEG video. Moreover, Agi and Gong
demonstrated that some scene contents are still visible by
directly playing back the selectively encrypted video stream
on a normal conventional decoder. Maples and Spanos
presented a similar approach called AEGIS. All I-frames in an
MPEG-video stream are encrypted, while P- and B-frames are
just left unencrypted. The AEGIS algorithm is almost same as
SECMPEG level 2.
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Fig. 5 The Video Encryption Algorithm proposed by Qiao and
Nahrstedt. MPEG packets are shuffled using key information
for fast, efficient encryption
Qiao and Nahrstedt introduced this algorithm called Video
Encryption Algorithm (VEA) which reduces the
computational complexity to almost half. This video
encryption algorithm is detailed in Fig above. Half bit stream
is encrypted with a naive encryption algorithm such as AES
and it is then used as key to XOR with the other half bit
stream. The basic VEA algorithm is so vulnerable to plaintext
attacks because an attacker can recover the whole frame from
the knowledge of either the odd list or the even one. A 2n-bits
random key (KeyM) is used to split the 2n-byte chunk
randomly into two lists instead of the fixed odd-even pattern
in the basic VEA. Thus, VEA also results in increased key
management issues.
3.2.5 Pre-compression Encryption Algorithm
While encrypting the video content before compressing is
possible, it also has some very serious limitations that are
crucial for mobile devices:
1. Pre-compression encryption implies encrypting
uncompressed or raw bits which will waste a lot of
computational resources. 

2. Output of encryption is generally a random bit stream
with absence of repetition, resulting in compression operation
highly inefficient for general case. For instance, lets consider
encrypting one specific HD video of a simple resolution of
480p (852 × 480) with Advanced Encryption Standard. It will
need 2.3 Million cycles of AES/sec for encoding (and then for
decoding) that video on portable device. Also, the
compression resultant will mostly be missing as AES output
bits is genrally random with almost no possibility of
compression without loss. 

A famous example is work of Diplin and Pazarci. The
scrambler is clear to MPEG-2 compression. Before coding the
video, it encrypts it in the BRG (blue, red, green) color space
by implementing four hidden linear transformations. This
method manages the efficiency of compression of video codec
but it has been found to be risky in brute force attacks.
Fig. 6: Pre-compression encryption scheme proposed by
Pazarci and Diplin
3.2.6 Selective Encryption
• Selective Encryption algorithm is a hybrid of
Arnold’s Cat map, image hiding and modified IDEA
technique.
• This method involves encryption of a subset of a data.
The main goal of this method is to reduce the amount
of data to be encrypted meanwhile, maintaining the
same level of security.
• Selective Encryption is better practice in constrained
communication for eg real time networking, which
helps in achieving scalability.
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Before we study the actual algorithm we should actually
know few things to understand the algorithmbetter:
1. Arnold’s Cat Map(ACM): it is named after a
Russian scientist who used a cat’s image to invent
this method.
The image is hit with a transformation which
randomizes the organization of the pixels. This is
depicted in Fig 7.
Fig 7: Arnold’s map permutation process
Hence the pixels will degenerate into unintelligent
order to produce encrypted image.
2. Modified IDEA Cryptography Technique :
The original IDEA technique is time consuming,
hence we modify it by changing the 25-bit shift
to 16-bit shift as shown in Fig 8.
Rest complete method remains the same.
Fig 8: Key generation for modified
IDEA
• Selective Encryption is carried out in following 3
steps :
1. Apply hiding technique to complete image.
2. Apply the ACM to the entire picture.
3. Apply Modified IDEA to the resulting image body.
Fig 9: Block Diagram for Selective Encryption Technique
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3.2.7 Joint Video Compression and Encryption (JVCE)
Approach
The principle thought behind joint coding is to incorporate
encryption into compression operation by parameterization of
the compression blocks, and not adjusting the compressed bits.
Entropy Coding and Wavelet Transform are the two main
compression blocks where this approach has been applied.
JVCE combines both encryption and compression into one
single operation making it easy for embedded devices and
mobiles to ensure security of multimedia with its low budget
of power. By integrating compression and encryption
operations as a whole, JVCE approach reduces the latency of
encryption which is useful in delivering real-time videos. This
approach generally does not change the compressed bit
streams, but it changes the way compressed bit stream is
acquired. This integration permits exploiting the hierarchical
representation of signal in a transform domain, as used by
most video and image compression techniques, for providing
the advanced functionalities needed by numerous modern
applications. The ISO/IEC JPEG 2000 Part 9 (JPSEC)
standard shows how security and comparison can coexist and
take advantage of each other.
JVCE scheme has emerged as a totally new paradigm of
encryption without proper encryption of video contents which
gives them advantages in terms of computations, mobility, and
friendliness to post-compression operations. However, we
observed that it has been broken particularly against known-
plaintext attacks. For designing an efficient encryption key for
the mobile applications, we suggest that we should develop
JVCE algorithms for different video coding blocks and then
efficiently integrate those into a common framework. An
efficient integration will invalidate most of the cryptanalysis
and thus the combined system will give a higher degree of
security than any other currently existing ciphers. Including
some efficient scrambling operations into this design is meant
to complicate input–output relationships at various levels.
3.3 Comparison of Algorithms
4. Multimedia Big Data Systems and Frameworks
The same structure as Chapter 3 will be followed. After
classifying the systems and frameworks, they will be
explained and reviewed. Then the comparison of these
systems will be made.
4.1 A Classification of the Systems and Frameworks
4.1.1 The Framework for Authorization Mechanism for
Multimedia Big Data
This framework is a hybrid solution which aims to control
multimedia big data sharing policies. It offers a solution for
privacy policy composition and enforcement for online
multimedia data. The mechanism lets users(multimedia big
data owners), not administrators to compose their own policy
for their multimedia big data while ensuring the logical
consistency.
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Fig. 10: Functional view of Authorization Mechanism
Framework.
4.1.2 HuaVideo: Secure HTML5 Video Providing System
HuaVideo is a video server system that is designed to provide
substantial capacity to big HTML5 video data and protect the
content[17]. It uses Distributed Database for video storage.
The system ensures that the server content can't be
downloaded by typical means.
4.1.3 Big Data Privacy via Hybrid Cloud
With the increasing amount of medical systems, surveillance
systems or social networks it is getting more and more
difficult to store and manage these data in a cheaper way.
Cloud computing is the best solution to this issue since it uses
provisioning on demand mechanism and method of pay-per-
use.
4.2 A Review of the Systems and Frameworks
4.2.1 The Framework for Authorization Mechanism for
Multimedia Big Data
The framework for authorization mechanism for multimedia
big data offers a solution for security policy for huge
multimedia big data systems which have large number of
devices and users. The objective of the framework is to let
users to exchange data with users whom they authorize and
allow them to manage their private multimedia data in terms
of access and management in a secure system. Especially in
the healthcare domain this system is crucial, because the
framework allows patients the ownership of their health
records which is enforced by law.
Since the amount of data and the number of users are high in
these systems, the structure is complex and there are some
design requirements that should be applied to keep the system
in control.
• The solution should be location-aware, context-aware and
real time. These benefits ensures mobility.
• The security policy shouldn’t have high complexity. Every
user will be able to compose their own individual policies,
so it is assumed that they can be naive.
• The data must be collected in an organized manner in
compliance with security policies.
• Requests for data access should specify the details and
intentions for how the data will be used.
The framework also uses an improved Role Based Access
Control(RBAC) model called Generalized Spatio-temporal
Role Based Access Control(GST-RBAC) to handle the context
requirements for multimedia big data security. RBAC has four
parts consisting of a set of users, permissions, sessions and
roles. The improved model grants specification of temporal
and spatial constraints on role enabling, user role assignment,
role-permission assignments [5].
The mechanism is designed based on Secure User Data
Repository System (SUDRS) [5] that is a hybrid approach for
composition of privacy rules for user data. The solution has
four components with some databases. The system
architecture can be seen in Fig. 11 and the functional view of
those components are shown in Fig. 10.
13
Fig. 11: Systemarchitecture for Authorization Mechanism
Framework.
The system can be explained with a basic scenario. The owner
of data(user)’s primary doctor is allowed to see the medical
records of the user. The doctor wants to consult another doctor
for an opinion. But, the privacy policy of the patient may not
allow to share information that is related to identity other than
the primary doctor. In this situation, the system builds a
filtered view of the original version and the private
information such as date of birth, full name are changed. The
original and the filtered data are kept in different databases.
These disclosure rules that controls the access are defined by
the owner of data, consumers(entities that want to access data)
and contributor(originators of the generated data). The most
critical parts that allow systemto maintain data security are:
• Composition and verification of originator disclose rules,
general disclosure rules and access rules,
• Composition and Verification of Originator Disclosure
Rules
• Composition and Verification of Disclosure Rules
• Enforcement of Disclosure Rules
Fig. 12: Pseudo-code for access rules verification and
composition.
Fig. 13: Pseudo-code for Originator Disclosure Rules
verification and composition.
The first component as shown in Fig. 12. lets consumers to
define their access rules. After the personal information of the
customer is entered, the consumer is authenticated. If this step
is successful, the consumer defines the access rules. In the last
step, the access rules are verified to check if they are
consistent.
Process for Composition and verification of Originator
Disclosure Rules is shown in Fig.13. In this part the disclosure
rules that are composed by originator is uploaded to the
system. The data type could be image, video or text. A list of
corresponding users, roles, location and time is created by the
contributor. The composition is verified as it’s done in the first
step.
14
Fig. 14: Pseudo-code for Disclosure Rules verification and
composition.
Fig. 15: Pseudo-code for Disclosure Rules enforcement.
Third component is for disclosure rule composition. The steps
for this process can be seen in Fig. 14. In this component the
owner selects with which consumer the data can be shared.
The user also has the opportunity to select time and location.
The last component enforces the disclosure rules by checking
the rules that are held in the data repository system and
compares these rules with the context parameters.
4.2.2 HuaVideo: Secure HTML5 Video Providing System
HTML5 videos are getting more popular everyday since they
don’t require an additional plug-in like Flash videos and the
browsers has an integrated player to show these type of
videos. However there are some challenges about the security
and storage of HTML5 video big data :
• The security is an issue for HTML5 videos since the video
URL can easily be found in source code. This makes it very
easy to download the video.
• Videos also tend to occupy more space than other
multimedia big data types. For that reason video server
capacity has to be large.
• Storage should be scalable, systemadministrators should be
able to add more servers securely.
HuaVideo System address all these issues[17]. It is a video
server system that offers scalable big video data storage and
content security.
As expected HuaVideo doesn’t use basic HTTP/1.1
authentication system. This procedure sends the data in clear
text which is very easy to capture. Instead of this Digest
authentication mechanism is used to transfer the private user
data in an encrypted form.
Overview of the Architecture:
In order to accomplish the objective of building a secure and
scalable video big data server, there are some design standards
that HuaVideo follows:
• In order to extend the server capacity effectively,
distributed storage strategies are applied.
• User has to be authenticated when he/she tries to access to
server.
• An encrypted URL is generated to ensure each link can be
accessed once.
• Multiple servers are placed to make video content access
faster.
• Checking the header of HTTP request shouldn’t be enough
to download the video.
15
Fig. 16: Architecture overview of HuaVideo.
Fig. 17: Procedure of Access Control of HuaVideo.
The high level overview of the architecture can be seen in Fig
17. There are numerous web servers that are connected to
database server clusters. Users access to the content through
the closest web server. The load balancer is responsible for
this allocation.
User Access Procedure:
This procedure is shown in Fig. 17. First the client should sign
into the server. If the result of the authentication is OK, the
access is given to the client. In case the client sends the URL
to someone else, the person who has the link will get an error.
Downloading the video is only limited to header. The user
won’t be able to get the other parts of the video.
Storage Architecture:
DDBS(Distributed Database System) is run on each server.
DDBS stores every data, including user info, comments and
the actual video files.
The network has the Peer-to-Peer(P2P) architecture which
allows administrators to add or remove a server at anytime.
Implementation:
• HuaVideo’s data services provider is MongoDb. Database
systems like MySql were mainly modeled for smaller
volume of data. They were also not modeled for single
server structure[18]. MongoDb is a database systemthat is
designed for big data and solves these issues. It’s query
procession is fast and it’s service is scalable. MongoDb has
a plug-in called GridFs that divides each file into smaller
pieces and put these smaller data on different servers. This
is perfect for multimedia big data since they usually have a
large volume.
• Script language of the systemis PHP(version 5.5).
• OGG and MPEG-4 are the video formats.
• Memcached is used to store and clear URLs.
• Browsers and servers are informed by HTTP headers which
carry a lot of information. HuaVideo uses the header to
prevent users to download the video. HTTP request header
has a Range field that gets the fragmentary content.
HuaVideo ensures that download software doesn’t send a
request that contains Range field to make the content non-
downloadable.
16
4.1.3 Big Data Privacy via Hybrid Cloud[12]
Cloud Computing is a low cost and more attractive solution to
big data. However the security of data stored in public cloud is
still a concern.
Firstly, multimedia big data of different organization contain
sensitive data.
Secondly, Cloud Service Providers (CSP) have access to that
sensitive data stored in public cloud.
The basic idea behind using Hybrid Cloud is to separate
sensitive data and non-sensitive data and storing them in
trusted private cloud and untrusted public cloud respectively.
But, then this would lead to the need of large amount of
storage private clouds.
Hence, we study this framework to utilize hybrid cloud as
much as possible with minimum cost and storage space.
Methodology of Big Data Privacy using Hybrid cloud:-
● System and Threat Model :
Figure 18 indicates an architecture of Hybrid Cloud. Original
data comes from private cloud and is processed on to server
within the private cloud.
The data is directly sent to public cloud if it is not sensitive.
Else process the remaining sensitive data. Once the processing
is done all the data is passed to public cloud and only a small
amount of sensitive data is stored in private cloud.
Whenever data is needed both public and private cloud are
contacted for the same.
Fig. 18: Architecture of Hybrid Cloud
● Goals of the design
Basic design goals are to achieve data privacy as well as
reduce the following:
1. Quantity of data inside private cloud
2. Communication overhead in between public and
private cloud
3. The deferral presented by interchanges in between
private and open cloud
● Privacy of Image Data
This section describes about achieving Image Data privacy.
The following table represents the notations for the same.
TABLE 2: Notations for image data privacy
● Step 1: Divide image into blocks
We partition a large picture (size of N × N) into n number of
blocks, where every piece has the same size k × k. For
instance, an image has a size of 256 × 256, the measure of
every piece (k ×k) is set to 32×32. The picture is partitioned
into n = (256 ÷ 32) × (256 ÷ 32) = 64 pieces.
● Step 2: Mapping Function
Use one-to-one mapping function to produce a ciphered value
from original pixel value
P’ = module(m x p,n) + [p/(n/g)]
Figure 19 shows original and encrypted image as an example.
17
Fig. 19: Original and Encrypted Image
● Step 3: Random Shuffle of Blocks
To make the modified image unrecognizable just shuffle the
image blocks by bunching N blocks into multiple groups
randomly each of size M.
● Step 4: Image Recovery
At the point when a picture is requested,the solicitation is sent
to both the private cloud and open cloud in the meantime.
1. First, we generate shuffle order permut using
Algorithm 1.
2. Second, we re-arrange shuffled image blocks from
the public cloud, which gives us transformed image.
3. Third, we get random values from private cloud, and
then utilize them to recover the original image from
the transformed image.
Fig. 20: Obtaining Shuffle Order Algorithm
4.3 A Comparison of the Systems and Frameworks
Table 3: Comparison of the Systems and Frameworks
18
5. Multimedia Big Data Security Challenges
Multimedia big data has huge volume and usually stored in
multiple different places. While providing constant access to
this data and managing the massive amounts of volume,
keeping the system secure could be a daunting task. There are
a lot of multimedia big data security challenges as can be seen
in Fig. 21. that are about maintaining a secure access to users
and protecting the data fromcorruption and online attacks[13].
Fig. 21: Multimedia Big Data Security Challenges
Multimedia big data has huge variety. This amplifies the
challenges that are already addressed in traditional
security[14] and makes access management harder. Different
data sources have different access restrictions. As a result
balancing the security for the data sources with the necessity
to extract meaning from the multimedia data becomes a
daunting task.
Multimedia big data systems are typically distributed. These
distributed environments are much more complexand prone to
attack than single database servers. Since the systems are
distributed geographically there is a need for physical security
controls[14]. There are also a huge number of servers and this
raises the chances of inconsistency of the server
configurations. Inconsistency makes the environment
vulnerable.
Organizations and companies need to guarantee that the utility
of the information and privacy are balanced[15]. Prior saving
the data in database, organizations make sure that the data is
anonymized enough. For example, unique identifier for clients
should be removed. But, a new challenge arises here. It might
not be sufficient to ensure that the information will stay
anonymized even after removing special identifiers. If cross-
reference technique is used on anonymized information with
other accessible information, it could be possible to de-
anonymize the information.
Establishing ownership of data is a noteworthy challenge
while using multimedia big data. Storing the multimedia big
data in the cloud is a widely used way. This requires an
establishment of a trust boundary between owners of the data
and data storage[15].
There are a lot of big data tools. The design of these tools may
lack security features such as encryption of information that is
sent between nodes and authentication. It’s also not easy to
define a security policy while using these tools[14]. The issue
of encryption is a huge challenge when storing multimedia big
data.
Multimedia big data is a relatively new concept in the
industry, so the best practices are not fully known yet[15].
New security problems arise everyday, therefore there is a
need for more research to make the systems more secure.
6. Conclusion
In this paper, we presented seven different
encryption/decryption algorithms and three
frameworks/schemes about multimedia big data security. They
were thoroughly classified, reviewed and compared. Since the
best practices for multimedia big data security are not fully
known yet and there are not many frameworks, tools or
algorithms, there is a need for more research about this issue.
19
7. References
[1] J. Gao, S. Li, T. Zhang and Y. Park. “A Sticky Policy
Framework for Big Data Security”, The First IEEE
International Conference on Big Data Computing Service, and
Applications, 2015.
[2] C. Ye, Z. Xiong, Y. Ding, J. Li, G. Wang, X. Zhang and K.
Zhang. “Secure Multimedia Big Data Sharing in Social
Networks Using Fingerprinting and Encryption in the
JPEG2000 Compressed Domain”, IEEE 13th International
Conference on Trust, Security and Privacy in Computing and
Communications, 2014.
[3] W. Zhu, P. Cui, and Z. Wang. “Multimedia Big Data
Computing“, IEEE Journals & Magazines, vol. 22, no. 3, pp.
96 - c3, 2015.
[4] S. Agaian and O. Caglayan. “Fast Encryption Method
Based on New FFT Representation for the Multimedia Data
System Security”, IEEE International Conference on Systems,
Man, and Cybernetics, pp. 1519 - 1524, 2006.
[5] A. Samuel, M.I. Sarfraz, H. Haseeb, S. Basalamah and A.
Ghafoor. “A Framework for Composition and Enforcement of
Privacy-Aware and Context-Driven Authorization Mechanism
for Multimedia Big Data”, IEEE Transactions On Multimedia,
vol. 17, no. 9, pp. 1484-1494, 2015.
[6] C. Tankard. (2012, July) Big data security [Online].
Available:
http://www.sciencedirect.com/science/article/pii/S1353485812
700636
[7] M. Chen. “A Hierarchical Security Model for Multimedia
Big Data”, International Journal of Multimedia Data
Engineering and Management, vol. 5, issue 1, 2014.
[8] “Big Data, Big Security Challenges” [Online]. Available:
http://www.vormetric.com/data-security-solutions/use-
cases/big-data-security
[9] M.A. Hossain. “Framework for a Cloud-Based Multimedia
Surveillance System”, International Journal of Distributed
Sensor Networks, vol. 2014, 2014.
[10] A. Pande and J. Zambreno. “Algorithms for Secure
Multimedia Delivery over Mobile Devices and Mobile
Agents” [Online]. Available:
http://web.cs.ucdavis.edu/~amit/BookChapter/Algorithms%20
for%20secure%20multimedia%20delivery%20over%20mobil
e%20devices%20and%20mobile%20agents.pdf
[11] M. Chen, S. Mao and Y. Liu. “ Big Data: A Survey”,
Mobile Networks and Applications, vol. 19, issue 2, pp. 171-
209, 2014.
[12] X. Huang and X. Du. “Achieving Big Data Privacy via
Hybrid Cloud”, IEEE INFOCOM Workshops: 2014 IEEE
INFOCOM Workshop on Security and Privacy in Big Data,
pp. 512 - 517, 2014.
H. Zhao. “A Novel Video Authentication Scheme with Secure
CS-Watermark in Cloud”, IEEE International Conference on
Multimedia Big Data, pp. 358-361, 2015.
[13] “Big Data Security Challenges” [Online]. Available:
http://www.forbes.com/sites/emc/2014/02/03/big-data-
security-challenges/
[14] “How to Manage Big Data’s Big Security Challenges”
[Online]. Available: http://data-informed.com/manage-big-
datas-big-security-challenges/
[15] “Big Data Security - Challenges & Solutions” [Online].
Available: https://www.mwrinfosecurity.com/articles/big-
data-security---challenges-solutions/
[16] “ Cloud Computing Experts Detail Big Data Security and
Privacy Risks” [Online] Available: http://data-
informed.com/cloud-computing-experts-detail-big-data-
security-and-privacy-risks/
[17] Y. Wu and Y. Zhang. “HuaVideo: Towards a Secure,
Scalable and
Compatible HTML5 Video Providing System”, 2014 11th
Web Information System and Application Conference, pp. 81-
85, 2014.
[18] “What Is Big Data?” [Online]. Available:
https://www.mongodb.com/big-data-explained
[19] R. Ridzon and D. Levicky. “Multimedia security and
multimedia content protection”, 51st International Symposium
ELMAR, 2009
[20] S. Byun and B. Ahn. “More on the multimedia data
security for e-commerce”, Information Technology: Research
and Education, pp. 412-415, 2003
[21] K. Nahrstedt, J. Dittman and P. Wohlmacher.
“Approaches to Multimedia and Security”, IEEE International
Conference on Multimedia and Expo, pp. 1275-1278, 2000

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  • 1. 1 Multimedia Big Data Security Navit Gaur Fall 2015
  • 2. 1 Abstract -- Multimedia big data is becoming more and more important as the amount of data shared over the web is increasing. With the rise of social networking sites like Facebook, Vine, Instagram, Spotify, the amount of multimedia data shared by the users is increasing exponentially. As the data grows rapidly, complex security issues arise. This paper will focus on the challenges, issues and needs that multimedia big data is facing in terms of security and different approaches to overcome these issues. Multimedia big data security frameworks, data encryption and decryption algorithms will be analysed and compared. 1. Introduction to Multimedia Big Data Security With the rise of digital technologies,it is possible nowadays to make an exact copy of the source. Multimedia data is represented as a bit of streams that can be saved on optical or magnetic media. Since digital recording is a process in which every part is read from source and then it is copied to a new destination it is possible to create an exact replica of the source media. Protection of multimedia big data is therefore a crucial problem. The essential security requirements for multimedia systems are as follows: · Confidentiality: Encryption can be used to prevent unauthorized entities from getting secret information. · Data integrity: Any changes in the data can be discerned by using robust and fragile watermarking, digital signatures and message authentication codes. · Data origin authenticity: Proof of origin can be verified using message authentication codes, digital signatures and fragile and digital watermarking. · Entity authenticity: Authentication protocols can be used to ensure that the entities taking part in the communication are the ones they claim to be. · Non-repudiation: Non-repudiation mechanisms can be used to prove whether a particular event or action happened to any parties involved. The event or action can be generation, sending, receipt or transport of a message. Non-repudiation certificates, non- repudiation tokens and protocols establish the accountability of information. Distributed multimedia applications can be secured using authentication control mechanisms. However, it is not enough to secure multimedia data broadcast. Multimedia data still needs to be encrypted during transmission. The next chapter provides a short introduction to encryption techniques and watermarking techniques. 2. Understanding of Multimedia Big Data Security[19][20][21] This chapter explains how the security requirements mentioned in the previous chapter can be obtained. · Confidentiality: Cipher systems can be used to hide information from unauthorized users. Private key and public key encryption can be used to encrypt the data. In streaming applications a large amount of data needs to be sent from the sender to the receiver. One of the problems of transmitting a huge amount of data is that data can change due to transmission errors, higher compression rates or scaling operations. If common encryption methods are used then the decryption of an encrypted block may fail because the original data could not be retrieved if one of the blocks is altered. A solution to these problems is to use partial encryption i.e. encrypt only certain parts of data instead of encrypting the whole data. · Data Integrity: Data integrity can be checked using one way has functions. Also some mechanisms detailed in the next section to can be used to detect any changes in the data. It is not possible to prevent data manipulation using these mechanisms but they make these manipulations detectable. A hash function maps strings of random length to strings of fixed length. Hash functions are public and hence can anyone knowing the function can check the integrity of data by calculating the hash value. As in multimedia applications, data can alter because of scaling or compression, it is not appropriate to apply hash functions directly to media. Instead it should be applied to the semantic data of the media stream. · Data Origin Authenticity: Authentication codes, digital signatures, fragile and robust digital watermarks can be used to determine data origin authenticity. These mechanisms can also be used to maintain data integrity. All these mechanisms are detection mechanisms and hence they cannot prevent data manipulation but can allow to detect if there was an alteration in data. Digital signatures can be used to ensure authenticity of multimedia data by using public key encryption systems. Digital signatures should not be applied directly to the multimedia data as the image
  • 3. 2 processing techniques like conversion or scaling maybe used on the multimedia data. Once these operations are applied on the multimedia data it is changes irreversibly. Although the content was not changed the digital signature verification will fail. Digital signatures should be used on the feature codes of multimedia data that are not changed during operations like scaling or compression. In digital watermarking the multimedia data is slightly modified and the verification data is embedded in it rather than being appended to it. Anyone with the proper secret key can use the watermark to determine whether the data was altered or not by checking the embedded information. The problem with watermarking techniques is that it is not possible to embed a large amount of data at a higher rate for the verification. · Entity Authenticity: Authentication protocols can be used to ensure that the parties taking part in the communication are indeed who they claim to be. One of the simplest example of an authentication protocol is the challenge response protocol in which the verifier sends a randomly generated number to the claimant. The claimant generates a value using the challenge and a secret and returns it to the verifier. The verifier can then check that the claimant has the appropriate secret key. · Non-repudiation: Non-repudiation mechanisms based on public key and private key encryption systems are used to provide security techniques that can be used to link data and actions to their originators. By making use of these mechanisms it is possible to prove to the involved parties or third parties whether a particular even or action occurred. The event or action maybe creating a message, transmitting a message or receiving a message Cryptography is probably one of the most common methods of protecting multimedia data. Secret key encryption used the same key for encrypting and decrypting data. It requires that the secret key be exchanged between the sender and receiver before any transmission takes place. Although the speed of secret key encryption is acceptable the key needs to be exchanged in advance and that is its weakness. Public key encryption uses two keys. The key used for encryption is different from the one that is used for decryption. The public key is used for encryption and the private key is used for decryption. Anyone can use the public to encrypt the message but the only the user with the private key can decrypt it. This method is more convenient than the secret key method but the encryption and decryption takes longer. In digital watermarking the original data is modified and additional information is embedded into it which are undetectable during normal use but detectable by computers and software. This additional information that is embedded is called watermark. Digital watermarking should match the following requirements: · The embedded watermark should be resilient against any attacks performed by unauthorized entities. The aimof such attacks is to gain access to unwatermarked data by damaging or removing the embedded watermark. · The watermark embedded in the multimedia data should not cause any visual or audible changes in the data. The watermark should only be detectable with the help of computers and software. It should be almost impossible to remove or extract the embedded watermark from the data without appropriate access to the secret key. 3. Multimedia Big Data Security Algorithms This chapter will focus on security algorithms for multimedia big data security. The algorithms will be classified and then they will be reviewed thoroughly. In the last section of the chapter, the algorithms will be compared. 3.1 A Classification of the Algorithms 3.1.1 Fast Encryption Method Based on New FFT Representation The fast encryption method is based on Fast Fourier Transformation to secure sensitive information within multimedia data. This method has dual key security feature, since it’s not only the encryption key but the mapping or transformation structure should be available to breach the information or data. 3.1.2 Multimedia Big Data Sharing in Social Networks Using Fingerprinting and Encryption in the JPEG2000 Compressed Domain
  • 4. 3 The development of social interactive media, as exhibited by person to person communication locales, for example, Facebook and YouTube, consolidated with advances in mixed media content investigation, underscores potential dangers for vindictive utilize, for example, unlawful replicating, robbery, written falsification, and misappropriation. Subsequently, secure interactive media sharing and traitor tracing issues have gotten to be basic and critical in social network. Hence this algorithm is focused in securing social media data. 3.1.3 Scrambling One of the easiest form of encryption that is used for securing multimedia data is Scrambling. It uses encryption process that performs random permutations using some specific pattern to multimedia data. Image’s histogram remains the same, just the individual positions are shuffled. 3.1.4 Post-Compression Encryption Algorithm The Secure Real-time Transport Protocol, or the basic approach encrypts the compressed bit stream by packetizing the multimedia data and then encrypting every single packet using AES. It is secure but it has a huge computational overheads and also it is not conducive to different favourable properties of the compressed bit streams in general, owing to the encryption of compressed data. 3.1.5 Pre-Compression Encryption Algorithm Pre-compression encryption implies encrypting uncompressed or raw bits which will waste a lot of computational resources. 3.1.6 Selective Encryption Transmitted pictures may have diverse applications, for example, business, military and medicinal applications. So it is important to scramble picture information before transmission over the systemto save its security and anticipate unapproved access. This Selective Encryption results in highly correlated original and decrypted images. Hence is a good technique to use. 3.1.7 Joint Video Compression and Encryption (JVCE) Approaches The principle thought behind joint coding is to incorporate encryption into compression operation by parameterization of the compression blocks, and not adjusting the compressed bits. Entropy Coding and Wavelet Transform are the two main compression blocks where this approach has been applied. 3.2 A Review of the Algorithms 3.2.1 Fast Encryption Method Based on New FFT RepresentationThe FFT encryption method is based on secrecy systems, which is also the set of transformations. The algorithmic representation structure can be divided and observed as follows: (i) Splitting the Fast Fourier Transform into small sets of transformation. (ii) Decomposing the transformation using discrete orthogonal transforms. Fig. 1: Encryption method with dual key functionality. Let us now understand the FFT encryption using Walsh- Hadamard Transform (WHT). • Sylvester matrix is the base of WHT. • Hadamard functions form a set of orthogonal functions having value -1 or +1 which means they need only addition or subtraction for computation. • WHT matrix can be represented as H2 n = H2 n-1 H2 n-1 H2 n-1 -H2 n-1 where n=2,3 H1 = 1, H2 = 1 1 1 -1
  • 5. 4 • We have initially added to the eight-point recursive FFT in view of the Walsh-Hadamard change. This mapping can be appeared by the factorization as the accompanying: F8 = [P8][B8 2][D8][B8 1][P8][B8 2]T∏(m=1 to 3){ I2 m-1 © H2 © I2 3-m } (2) where [P8] is the row permutation matrix, which has the format as the accompanying : When k = 1 , 2 then we get [B8 1] and [B8 2] respectively as : The iterative algorithm for deriving H8 matrix is: H8 = ∏(m=1 to 3){ I2 m-1 © H2 © I2 3-m} We also defined Diagonal Matrix as : [D8] = diag{ 1,1,W3,3 , W4,4 , W5,5 , W6,6 , W7,7 , W8,8 } = diag{ 1,1,2-1i, 2-21, -2-2i , -2-55.6569i , 2-55.6569}
  • 6. 5 • Hence once we deduce the mapping structure our next goal is sensitive data encryption. Encryption equation for transformation is represented as: E8 = [P8][B8 2][S8][D8][B8 1][P8][B8 2]T ∏(m= 1 to3){ I2 m-1 © H2 © I2 3-m } (3) Fig. 2: A flow diagram to represent FFT encryption based on WHT. Flow diagram depicts the encryption approach inside of the transformation process. [x[O],x[l],...,x[7]j' is the info signal appeared in figure Y, on the left hand side. Likewise, [Y[o],Y[i],...,Y[7]]" is the yield, transformed signal. The procedure is done as the accompanying; first we separate the information picture into 8x8 pieces, and after that we encode the touchy data by utilizing the eq. (3) by the accompanying arrangement: TBlock8 = [E8][Block8]ET 8] After encryption, we converse change the recurrence segments of the information back to spatial space, before transmitting it in the public channel. As seen fromthe figure 2, the shuffling is accomplished by : As a matter of fact, the encryption demonstrated above, took place at the end but it could have been done at the beginning. Giving us an efficient encryption method which can change the location of shuffling. • Hence there is no constraint as in when to begin or end shuffling process. 3.2.2 Multimedia Big Data Sharing in Social Networks Using Fingerprinting and Encryption in the JPEG2000 Compressed Domain • This section presents implementation of Tree- Structured Harr (TSH) transformation homomorphically encrypted domain for fingerprinting using social network analyses with the aim of protecting social media data. • Fingerprinting Technique basically embeds users fingerprints into digital contents by making changes in host signal in such a way that the content remains the same.
  • 7. 6 • JPEG 2000 Code Based TSH Transform : The most commonly used signal processing tool is DWT, wherein TSH is generic wavelet transform. The fingerprinting plan in the TSH transform of the encrypted data empowers the proprietor to install unique finger print sequence into media content. Fingerprints embedding is done in encrypted domain using additive Homomorphic property in the selected embedded positions. Once the discrete TSH transform of the input image is done the JPEG 2000 transformation is divided into 3 sections : (i) Firstly quantize the wavelet transform coefficients. (ii) Divide the quantized coefficients into different bit planes and code them through several passes : at embedded block coding with optimized truncation(EBCOT) to give compressed byte stream. (iii) Lastly arrange the compressed byte stream into separate wavelet packets. Thus, it is possible to select bytes generated fromdifferent bit planes of different resolutions for joint fingerprinting and encryption for JPEG2000 image directly. • Fingerprints Embedding Procedure : To shield substance from unlawful redistribution after they are legitimately got by client, interactive media substance ought to be implanted into exceptional client data (e.g., fingerprints) which should be vague to the clients into every client's copy for following unlawful clients. Since the watermark-embedding procedure is performed in the compressed and encrypted space . For a compacted furthermore, scrambled JPEG2000 pictures, we implant the various hierarchical fingerprints into the compressed and encrypted various leveled subband of the TSH area. Suppose Nu is a set of users. Choosing encrypted byte stream in approximation subband to combine vector EX I = (ex1, ex2, ..., exI L) Choose another encrypted byte stream in all horizontal and vertical subbands to combine different vectors, such as EXO = (ex1, ex2, ..., exO L) for different community code segment embedding. Here EX I and EXO is the length of codeword and the user cpdeword encryption equations is : EFXk = EXO k + α ∗ Fk, k = 1, 2, ...,Nu Where α is the scale factor and Fk is the fingerprint information for user k. 3.2.3 Scrambling One of the easiest form of encryption that is used for securing multimedia data is Scrambling. It uses encryption process that performs random permutations using some specific pattern to multimedia data. Image’s histogram remains the same, just the individual positions are shuffled. The security that scrambling alone provides is relatively less. It reduces the efficiency of compression of video bit stream that leads to loss in compression and size increase of the video file. Scrambling is generally used as a simple way for encrypting live analog/digital video signals such as surveillance camera feeds where complex ciphers are eliminated because it causes delay in computation. Some general scrambling techniques are as follows: 1. Line Inversion Video scrambling: In this technique, whole or some portions of the signal scan lines are simply inverted. This method is comparatively cheap and easy to implement. Its shortcoming is that it provides low security.
 2. Sync Suppression Video scrambling: In this method, the vertical/horizontal line syncs are either made invisible or are completely deleted. This method provides a low-cost solution for Encryption and it also provides a good quality of video decoding. A common disadvantage is that the level of ambiguity reached by this technique depends on the content of video. 

  • 8. 7 3. Line Shuffle Video scrambling: In this technique, every signal line on the screen is rearranged. This scrambling method provides bettersecurity but it needs a lot of storage for re-ordering the screen. 
 4. Cut and Rotate Video scrambling: In this technique, every scan line is cut into parts and then combined in a permuted manner. This scheme provides a compatible video signal, gives an excellent amount of obscurity and good decode quality and stability. However, it requires specialized scrambling equipment. Compression algorithms have been designed for the unscrambled signals and they use the statistical characteristics of raw data. Once the signal is scrambled, these characteristics will change and the performance of the compression filter will be degraded. In Zig-Zag permutation method, in the place of mapping 8 × 8 blocks (as in DCT compression stage in video coder) to 1 × 64 vector in Zig-Zag order, it maps individual 8 × 8 blocks on to 1 × 64 vector by using a random permutation list (secret key). This method consists of three steps. 1. Generating a permutation list of cardinality 64.
 2. Splitting the coefficients according to list of permutation. 3. Sending the outcome to entropy coding method. But this method reduces the compression rate of video because the random permutation deforms the probability distribution of DCT (Discrete Cosine Transform) coefficients. A scrambling scheme of digital image should have a comparatively easy implementation, accommodating low delay operation and low cost decoding for real time interactive applications. It should be free fromcompression algorithmand should not cause any loss for the compression operation. We present here a case study of technique presented by Liu and Zeng for understanding the scrambling in a better way. Figure below contains an overview of that technique. Fig. 3: Scrambling Scheme Initially, the authors transform input signal into frequency domain by using Discrete Cosine Transform (DCT) or Discrete Wavelet Transform (DWT). Then the transform coefficients are divided into further operations which permute their values in the image. Motion vectors are matter of random sign modifications and shuffling. Along with that, a cryptographic key is used to manage scrambling. The motion vectors and scrambled coefficients are then sent to compression block for obtaining compressed bit stream. Users who are authorized can easily obtain the original main content back by using the same compression key. This scrambling operation is executed before compression, thus it allows preservation of properties of multimedia-specific compression like scalability and transcoding. It is easy for frequency domain scrambling to control the transparency (i.e., which portion of the video will be allowed in free access). Encryption/decryption methods are designed such that it preserves the properties of image transformed that the entropy coders are allowed to properly compress an image. Apart from secure and easy transcoding, framework of joint scrambling-compression provides many different advantages over those that execute scrambling on the compressed bit streams. Those advantages are: 1. Flexibility to encrypt selectively: In domain of frequency, it’s very easy to recognise which data parts are crucial for security. This permits to provide various levels of security and transparency. 2. Encrypting incompressible segments: It’s simple to detect which data parts are incompressible. For instance, coefficient sign bits are generally hard to compress; but still those are important for security purposes. This incompressible segment of data is selected for scrambling without impacting the total efficiency of compression. Data segments like motion vector information are generally compressed without any loss. Hence they can be selected to encrypt without the necessity of considering the transcoding issue, since this doesn’t makes sense for transcoder to recode the portion of compressed data. The selected data can easily be located in the frequency domain without causing any processing overhead. On the other side, since the compressed bit stream is generally variable length coded, it is usually difficult to perform fine scale selective encryption on compressed bit stream without causing bit overheads and processing. 
 3.Low vulnerability to channel errors: Encrypting data after compressing such as using AES over MPEG is more vulnerable to channel errors because a block of 128 bits in AES is bound together so that a single bit error in a block will cause synchronization word/bits of that block to be erroneous. It will be harder to recover from transmission errors in the
  • 9. 8 network since the synchronization information is hidden in the encrypted video stream. On the other hand, spatial scrambling in frequency domain has no such adverse effect on the resiliency of error. 
 4.Compatibility to transform domain signal processing: Scrambling consists of changing the spatial parts of individual frequency coefficients. Watermarking and other transform domain tasks can be easily performed without requiring a cryptographic key. 
Some of the techniques for scrambling are as follows: 
 1. Selective Bit Scrambling: The basic method scrambles the bits that are selected in transform coefficients for encrypting the image. Each bit of coefficient can be one of the three types. Significance bits for the coefficient are most significant bit of the value 1, and any of the preceding bits of the value 0. This constraints the magnitude of the coefficient to known range. Remaining magnitude bits are refinement bits that are used in refining the coefficient within a recognizable range. Sign bit says if the range is negative or positive. 
 2. Block Shuffling: In block shuffling, we divide every sub- band into multiple similar sized blocks. The block size can be different for various sub-bands. Within every sub-band, coefficient blocks are shuffled according to the table of shuffling which is generated using key. The table of shuffling generally will be distinct for various sub-bands, and it can differ for every frame. 
 3. Block Rotation: Every coefficient block is rotated to form encrypted blocks to improve security. 3.2.4 Post-compression Encryption Algorithm The Secure Real-time Transport Protocol, or the basic approach encrypts the compressed bit stream by packetizing the multimedia data and then encrypting every single packet using AES. It is secure but it has a huge computational overheads and also it is not conducive to different favourable properties of the compressed bit streams in general, owing to the encryption of compressed data. So many different algorithms have been proposed—which are format compliant, or have low computational requirements. Gadgegast and Meyer suggested a selective video encryption scheme called Secure MPEG or SECMPEG for the MPEG-1 video coding standard. See figure below for details. Fig. 4: Different levels of security offered by the SECMPEG algorithm (Meyer and Gadgegast). It offers various levels of security by encoding different parts of compressed bit stream: Algorithm 1: This encrypts headers from layer of sequence to layer of slice. 
 Algorithm 2: Along with that, it encrypts DCT coefficients of low frequency of each block in I-frames. 
 Algorithm 3: This encrypts complete I-frames and I-blocks in the B- and P-frames. 
 Algorithm 4: This encrypts complete MPEG-1 sequence with the basic process. 
 The approach has some notable limitations: Computations savings are not so significant because I-frames constitute 30%–60% of a MPEG video. Moreover, Agi and Gong demonstrated that some scene contents are still visible by directly playing back the selectively encrypted video stream on a normal conventional decoder. Maples and Spanos presented a similar approach called AEGIS. All I-frames in an MPEG-video stream are encrypted, while P- and B-frames are just left unencrypted. The AEGIS algorithm is almost same as SECMPEG level 2.
  • 10. 9 Fig. 5 The Video Encryption Algorithm proposed by Qiao and Nahrstedt. MPEG packets are shuffled using key information for fast, efficient encryption Qiao and Nahrstedt introduced this algorithm called Video Encryption Algorithm (VEA) which reduces the computational complexity to almost half. This video encryption algorithm is detailed in Fig above. Half bit stream is encrypted with a naive encryption algorithm such as AES and it is then used as key to XOR with the other half bit stream. The basic VEA algorithm is so vulnerable to plaintext attacks because an attacker can recover the whole frame from the knowledge of either the odd list or the even one. A 2n-bits random key (KeyM) is used to split the 2n-byte chunk randomly into two lists instead of the fixed odd-even pattern in the basic VEA. Thus, VEA also results in increased key management issues. 3.2.5 Pre-compression Encryption Algorithm While encrypting the video content before compressing is possible, it also has some very serious limitations that are crucial for mobile devices: 1. Pre-compression encryption implies encrypting uncompressed or raw bits which will waste a lot of computational resources. 
 2. Output of encryption is generally a random bit stream with absence of repetition, resulting in compression operation highly inefficient for general case. For instance, lets consider encrypting one specific HD video of a simple resolution of 480p (852 × 480) with Advanced Encryption Standard. It will need 2.3 Million cycles of AES/sec for encoding (and then for decoding) that video on portable device. Also, the compression resultant will mostly be missing as AES output bits is genrally random with almost no possibility of compression without loss. 
 A famous example is work of Diplin and Pazarci. The scrambler is clear to MPEG-2 compression. Before coding the video, it encrypts it in the BRG (blue, red, green) color space by implementing four hidden linear transformations. This method manages the efficiency of compression of video codec but it has been found to be risky in brute force attacks. Fig. 6: Pre-compression encryption scheme proposed by Pazarci and Diplin 3.2.6 Selective Encryption • Selective Encryption algorithm is a hybrid of Arnold’s Cat map, image hiding and modified IDEA technique. • This method involves encryption of a subset of a data. The main goal of this method is to reduce the amount of data to be encrypted meanwhile, maintaining the same level of security. • Selective Encryption is better practice in constrained communication for eg real time networking, which helps in achieving scalability.
  • 11. 10 Before we study the actual algorithm we should actually know few things to understand the algorithmbetter: 1. Arnold’s Cat Map(ACM): it is named after a Russian scientist who used a cat’s image to invent this method. The image is hit with a transformation which randomizes the organization of the pixels. This is depicted in Fig 7. Fig 7: Arnold’s map permutation process Hence the pixels will degenerate into unintelligent order to produce encrypted image. 2. Modified IDEA Cryptography Technique : The original IDEA technique is time consuming, hence we modify it by changing the 25-bit shift to 16-bit shift as shown in Fig 8. Rest complete method remains the same. Fig 8: Key generation for modified IDEA • Selective Encryption is carried out in following 3 steps : 1. Apply hiding technique to complete image. 2. Apply the ACM to the entire picture. 3. Apply Modified IDEA to the resulting image body. Fig 9: Block Diagram for Selective Encryption Technique
  • 12. 11 3.2.7 Joint Video Compression and Encryption (JVCE) Approach The principle thought behind joint coding is to incorporate encryption into compression operation by parameterization of the compression blocks, and not adjusting the compressed bits. Entropy Coding and Wavelet Transform are the two main compression blocks where this approach has been applied. JVCE combines both encryption and compression into one single operation making it easy for embedded devices and mobiles to ensure security of multimedia with its low budget of power. By integrating compression and encryption operations as a whole, JVCE approach reduces the latency of encryption which is useful in delivering real-time videos. This approach generally does not change the compressed bit streams, but it changes the way compressed bit stream is acquired. This integration permits exploiting the hierarchical representation of signal in a transform domain, as used by most video and image compression techniques, for providing the advanced functionalities needed by numerous modern applications. The ISO/IEC JPEG 2000 Part 9 (JPSEC) standard shows how security and comparison can coexist and take advantage of each other. JVCE scheme has emerged as a totally new paradigm of encryption without proper encryption of video contents which gives them advantages in terms of computations, mobility, and friendliness to post-compression operations. However, we observed that it has been broken particularly against known- plaintext attacks. For designing an efficient encryption key for the mobile applications, we suggest that we should develop JVCE algorithms for different video coding blocks and then efficiently integrate those into a common framework. An efficient integration will invalidate most of the cryptanalysis and thus the combined system will give a higher degree of security than any other currently existing ciphers. Including some efficient scrambling operations into this design is meant to complicate input–output relationships at various levels. 3.3 Comparison of Algorithms 4. Multimedia Big Data Systems and Frameworks The same structure as Chapter 3 will be followed. After classifying the systems and frameworks, they will be explained and reviewed. Then the comparison of these systems will be made. 4.1 A Classification of the Systems and Frameworks 4.1.1 The Framework for Authorization Mechanism for Multimedia Big Data This framework is a hybrid solution which aims to control multimedia big data sharing policies. It offers a solution for privacy policy composition and enforcement for online multimedia data. The mechanism lets users(multimedia big data owners), not administrators to compose their own policy for their multimedia big data while ensuring the logical consistency.
  • 13. 12 Fig. 10: Functional view of Authorization Mechanism Framework. 4.1.2 HuaVideo: Secure HTML5 Video Providing System HuaVideo is a video server system that is designed to provide substantial capacity to big HTML5 video data and protect the content[17]. It uses Distributed Database for video storage. The system ensures that the server content can't be downloaded by typical means. 4.1.3 Big Data Privacy via Hybrid Cloud With the increasing amount of medical systems, surveillance systems or social networks it is getting more and more difficult to store and manage these data in a cheaper way. Cloud computing is the best solution to this issue since it uses provisioning on demand mechanism and method of pay-per- use. 4.2 A Review of the Systems and Frameworks 4.2.1 The Framework for Authorization Mechanism for Multimedia Big Data The framework for authorization mechanism for multimedia big data offers a solution for security policy for huge multimedia big data systems which have large number of devices and users. The objective of the framework is to let users to exchange data with users whom they authorize and allow them to manage their private multimedia data in terms of access and management in a secure system. Especially in the healthcare domain this system is crucial, because the framework allows patients the ownership of their health records which is enforced by law. Since the amount of data and the number of users are high in these systems, the structure is complex and there are some design requirements that should be applied to keep the system in control. • The solution should be location-aware, context-aware and real time. These benefits ensures mobility. • The security policy shouldn’t have high complexity. Every user will be able to compose their own individual policies, so it is assumed that they can be naive. • The data must be collected in an organized manner in compliance with security policies. • Requests for data access should specify the details and intentions for how the data will be used. The framework also uses an improved Role Based Access Control(RBAC) model called Generalized Spatio-temporal Role Based Access Control(GST-RBAC) to handle the context requirements for multimedia big data security. RBAC has four parts consisting of a set of users, permissions, sessions and roles. The improved model grants specification of temporal and spatial constraints on role enabling, user role assignment, role-permission assignments [5]. The mechanism is designed based on Secure User Data Repository System (SUDRS) [5] that is a hybrid approach for composition of privacy rules for user data. The solution has four components with some databases. The system architecture can be seen in Fig. 11 and the functional view of those components are shown in Fig. 10.
  • 14. 13 Fig. 11: Systemarchitecture for Authorization Mechanism Framework. The system can be explained with a basic scenario. The owner of data(user)’s primary doctor is allowed to see the medical records of the user. The doctor wants to consult another doctor for an opinion. But, the privacy policy of the patient may not allow to share information that is related to identity other than the primary doctor. In this situation, the system builds a filtered view of the original version and the private information such as date of birth, full name are changed. The original and the filtered data are kept in different databases. These disclosure rules that controls the access are defined by the owner of data, consumers(entities that want to access data) and contributor(originators of the generated data). The most critical parts that allow systemto maintain data security are: • Composition and verification of originator disclose rules, general disclosure rules and access rules, • Composition and Verification of Originator Disclosure Rules • Composition and Verification of Disclosure Rules • Enforcement of Disclosure Rules Fig. 12: Pseudo-code for access rules verification and composition. Fig. 13: Pseudo-code for Originator Disclosure Rules verification and composition. The first component as shown in Fig. 12. lets consumers to define their access rules. After the personal information of the customer is entered, the consumer is authenticated. If this step is successful, the consumer defines the access rules. In the last step, the access rules are verified to check if they are consistent. Process for Composition and verification of Originator Disclosure Rules is shown in Fig.13. In this part the disclosure rules that are composed by originator is uploaded to the system. The data type could be image, video or text. A list of corresponding users, roles, location and time is created by the contributor. The composition is verified as it’s done in the first step.
  • 15. 14 Fig. 14: Pseudo-code for Disclosure Rules verification and composition. Fig. 15: Pseudo-code for Disclosure Rules enforcement. Third component is for disclosure rule composition. The steps for this process can be seen in Fig. 14. In this component the owner selects with which consumer the data can be shared. The user also has the opportunity to select time and location. The last component enforces the disclosure rules by checking the rules that are held in the data repository system and compares these rules with the context parameters. 4.2.2 HuaVideo: Secure HTML5 Video Providing System HTML5 videos are getting more popular everyday since they don’t require an additional plug-in like Flash videos and the browsers has an integrated player to show these type of videos. However there are some challenges about the security and storage of HTML5 video big data : • The security is an issue for HTML5 videos since the video URL can easily be found in source code. This makes it very easy to download the video. • Videos also tend to occupy more space than other multimedia big data types. For that reason video server capacity has to be large. • Storage should be scalable, systemadministrators should be able to add more servers securely. HuaVideo System address all these issues[17]. It is a video server system that offers scalable big video data storage and content security. As expected HuaVideo doesn’t use basic HTTP/1.1 authentication system. This procedure sends the data in clear text which is very easy to capture. Instead of this Digest authentication mechanism is used to transfer the private user data in an encrypted form. Overview of the Architecture: In order to accomplish the objective of building a secure and scalable video big data server, there are some design standards that HuaVideo follows: • In order to extend the server capacity effectively, distributed storage strategies are applied. • User has to be authenticated when he/she tries to access to server. • An encrypted URL is generated to ensure each link can be accessed once. • Multiple servers are placed to make video content access faster. • Checking the header of HTTP request shouldn’t be enough to download the video.
  • 16. 15 Fig. 16: Architecture overview of HuaVideo. Fig. 17: Procedure of Access Control of HuaVideo. The high level overview of the architecture can be seen in Fig 17. There are numerous web servers that are connected to database server clusters. Users access to the content through the closest web server. The load balancer is responsible for this allocation. User Access Procedure: This procedure is shown in Fig. 17. First the client should sign into the server. If the result of the authentication is OK, the access is given to the client. In case the client sends the URL to someone else, the person who has the link will get an error. Downloading the video is only limited to header. The user won’t be able to get the other parts of the video. Storage Architecture: DDBS(Distributed Database System) is run on each server. DDBS stores every data, including user info, comments and the actual video files. The network has the Peer-to-Peer(P2P) architecture which allows administrators to add or remove a server at anytime. Implementation: • HuaVideo’s data services provider is MongoDb. Database systems like MySql were mainly modeled for smaller volume of data. They were also not modeled for single server structure[18]. MongoDb is a database systemthat is designed for big data and solves these issues. It’s query procession is fast and it’s service is scalable. MongoDb has a plug-in called GridFs that divides each file into smaller pieces and put these smaller data on different servers. This is perfect for multimedia big data since they usually have a large volume. • Script language of the systemis PHP(version 5.5). • OGG and MPEG-4 are the video formats. • Memcached is used to store and clear URLs. • Browsers and servers are informed by HTTP headers which carry a lot of information. HuaVideo uses the header to prevent users to download the video. HTTP request header has a Range field that gets the fragmentary content. HuaVideo ensures that download software doesn’t send a request that contains Range field to make the content non- downloadable.
  • 17. 16 4.1.3 Big Data Privacy via Hybrid Cloud[12] Cloud Computing is a low cost and more attractive solution to big data. However the security of data stored in public cloud is still a concern. Firstly, multimedia big data of different organization contain sensitive data. Secondly, Cloud Service Providers (CSP) have access to that sensitive data stored in public cloud. The basic idea behind using Hybrid Cloud is to separate sensitive data and non-sensitive data and storing them in trusted private cloud and untrusted public cloud respectively. But, then this would lead to the need of large amount of storage private clouds. Hence, we study this framework to utilize hybrid cloud as much as possible with minimum cost and storage space. Methodology of Big Data Privacy using Hybrid cloud:- ● System and Threat Model : Figure 18 indicates an architecture of Hybrid Cloud. Original data comes from private cloud and is processed on to server within the private cloud. The data is directly sent to public cloud if it is not sensitive. Else process the remaining sensitive data. Once the processing is done all the data is passed to public cloud and only a small amount of sensitive data is stored in private cloud. Whenever data is needed both public and private cloud are contacted for the same. Fig. 18: Architecture of Hybrid Cloud ● Goals of the design Basic design goals are to achieve data privacy as well as reduce the following: 1. Quantity of data inside private cloud 2. Communication overhead in between public and private cloud 3. The deferral presented by interchanges in between private and open cloud ● Privacy of Image Data This section describes about achieving Image Data privacy. The following table represents the notations for the same. TABLE 2: Notations for image data privacy ● Step 1: Divide image into blocks We partition a large picture (size of N × N) into n number of blocks, where every piece has the same size k × k. For instance, an image has a size of 256 × 256, the measure of every piece (k ×k) is set to 32×32. The picture is partitioned into n = (256 ÷ 32) × (256 ÷ 32) = 64 pieces. ● Step 2: Mapping Function Use one-to-one mapping function to produce a ciphered value from original pixel value P’ = module(m x p,n) + [p/(n/g)] Figure 19 shows original and encrypted image as an example.
  • 18. 17 Fig. 19: Original and Encrypted Image ● Step 3: Random Shuffle of Blocks To make the modified image unrecognizable just shuffle the image blocks by bunching N blocks into multiple groups randomly each of size M. ● Step 4: Image Recovery At the point when a picture is requested,the solicitation is sent to both the private cloud and open cloud in the meantime. 1. First, we generate shuffle order permut using Algorithm 1. 2. Second, we re-arrange shuffled image blocks from the public cloud, which gives us transformed image. 3. Third, we get random values from private cloud, and then utilize them to recover the original image from the transformed image. Fig. 20: Obtaining Shuffle Order Algorithm 4.3 A Comparison of the Systems and Frameworks Table 3: Comparison of the Systems and Frameworks
  • 19. 18 5. Multimedia Big Data Security Challenges Multimedia big data has huge volume and usually stored in multiple different places. While providing constant access to this data and managing the massive amounts of volume, keeping the system secure could be a daunting task. There are a lot of multimedia big data security challenges as can be seen in Fig. 21. that are about maintaining a secure access to users and protecting the data fromcorruption and online attacks[13]. Fig. 21: Multimedia Big Data Security Challenges Multimedia big data has huge variety. This amplifies the challenges that are already addressed in traditional security[14] and makes access management harder. Different data sources have different access restrictions. As a result balancing the security for the data sources with the necessity to extract meaning from the multimedia data becomes a daunting task. Multimedia big data systems are typically distributed. These distributed environments are much more complexand prone to attack than single database servers. Since the systems are distributed geographically there is a need for physical security controls[14]. There are also a huge number of servers and this raises the chances of inconsistency of the server configurations. Inconsistency makes the environment vulnerable. Organizations and companies need to guarantee that the utility of the information and privacy are balanced[15]. Prior saving the data in database, organizations make sure that the data is anonymized enough. For example, unique identifier for clients should be removed. But, a new challenge arises here. It might not be sufficient to ensure that the information will stay anonymized even after removing special identifiers. If cross- reference technique is used on anonymized information with other accessible information, it could be possible to de- anonymize the information. Establishing ownership of data is a noteworthy challenge while using multimedia big data. Storing the multimedia big data in the cloud is a widely used way. This requires an establishment of a trust boundary between owners of the data and data storage[15]. There are a lot of big data tools. The design of these tools may lack security features such as encryption of information that is sent between nodes and authentication. It’s also not easy to define a security policy while using these tools[14]. The issue of encryption is a huge challenge when storing multimedia big data. Multimedia big data is a relatively new concept in the industry, so the best practices are not fully known yet[15]. New security problems arise everyday, therefore there is a need for more research to make the systems more secure. 6. Conclusion In this paper, we presented seven different encryption/decryption algorithms and three frameworks/schemes about multimedia big data security. They were thoroughly classified, reviewed and compared. Since the best practices for multimedia big data security are not fully known yet and there are not many frameworks, tools or algorithms, there is a need for more research about this issue.
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