A Proposed SAFER Plus Security algorithm using Fast Walsh Hadamard transform for Bluetooth Technology

International Journal of Wireless & Mobile Networks (IJWMN), Vol 1, No 2, November 2009
80
A Proposed SAFER Plus Security algorithm
using Fast Walsh Hadamard transform for
Bluetooth Technology
D.Sharmila1
, R.Neelaveni2
1
(Research Scholar),
Associate Professor,
Bannari Amman Institute of Technology, Sathyamangalam.
Tamil Nadu-638401.
sharmiramesh@rediffmail.com
2
Asst.Prof. PSG College of Technology,
Coimbatore.Tamil Nadu -638401.
rnv@eee.psgtech.ac.in
ABSTRACT
In this paper, a modified SAFER plus algorithm is
presented. Additionally, a comparison with various
security algorithms like pipelined AES, Triple DES,
Elliptic curve Diffie Hellman and the existing SAFER plus
are done. Performance of the algorithms is evaluated
based on the data throughput, frequency and security
level. The results show that the modified SAFER plus
algorithm has enhanced security compared to the existing
algorithms.
Key words: Secure And Fast Encryption Routine, Triple Data
Encryption Standard, Pipelined Advanced Encryption
Standard, Elliptic Curve Diffie Hellmann, Pseudo Hadamard
Transform, Encryption and Decryption.
1. Introduction
Bluetooth technology was developed to replace
cumbersome wires in portable and personal electronic devices
with radio frequency wireless communication. It has since
found its way into numerous mobile applications as well as
home and automobile use. Bluetooth is an open standard for
short-range radio frequency (RF) communication. Bluetooth
technology is used primarily to establish wireless personal
area networks (WPAN), commonly referred to as ad hoc or
peer-to-peer (P2P) networks. This allows users to form ad hoc
networks between a wide variety of devices to transfer voice
and data. There have been several versions of Bluetooth, with
the most recent being 2.0 + Enhanced Data Rate (EDR)
(November 2004) and 2.1 + EDR (July 2007). While 2.0 +
EDR provided faster transmission speeds than previous
versions (up to 3 Mbits/second), 2.1 + EDR provides a
significant security improvement for link key generation and
management in the form of Secure Simple Pairing (SSP).
Bluetooth is a technology for short range wireless data and
realtime two-way voice transfer providing data rates up to 3
Mb/s. It operates at 2.4 GHz frequency in the free ISM-band
(Industrial, Scientific, and Medical) using frequency hopping
[18]. Bluetooth can be used to connect almost any kind of
device to another device. Typical range of Bluetooth
communication varies from 10 to 100 meters indoors.
Bluetooth technology and associated devices are susceptible
to general wireless networking threats, such as denial of
service attacks, eavesdropping, man-in-the-middle attacks,
message modification, and resource misappropriation. They
are also threatened by more specific Bluetooth-related attacks
that target known vulnerabilities in Bluetooth
implementations and specifications. Attacks against
improperly secured Bluetooth implementations can provide
attackers with unauthorized access to sensitive information
and unauthorized usage of Bluetooth devices and other
systems or networks to which the devices are connected. [1]
There are several security algorithms available to ensure
the security in wireless network devices. Some of the major
methods are AES, DES, Triple DES, IDEA, BLOWFISH,
SAFER+,ECDH etc. The SAFER+ algorithm is based on the
existing SAFER family of ciphers. Although SAFER+ is the
most widely used algorithm, it seems to have some
vulnerabilities. The objective is to compare the various
security algorithms like pipelined AES[14], triple DES
[15][16], Elliptic Curve Diffie Hellman (ECDH), Existing
SAFER+ and Proposed SAFER+ algorithm The Proposed
SAFER+ algorithm has rotation block between every round
of Existing SAFER+, PHT is replaced by Fast Psuedo
Hadaamard transform (FPHT) and first round inputs are
added or ored with the third round inputs and fifth round
inputs are added or ored with the seventh round inputs. Thus
the proposed SAFER+ has higher data throughput and
frequency. This proves that proposed SAFER+ algorithm has
better data throughput and frequency than the existing
algorithms.
In this paper, section 2 describes the overview of
Bluetooth technology and security. section 3 deals with the
Existing SAFER+ algorithm. The Proposed SAFER+

81
algorithm is explained in section 4. A section 5 deal with the
results, Section 6 refers the conclusion.
2. Bluetooth Security Architecture
Bluetooth architecture is described in Section 2.1.
Section 2.2 explains the Bluetooth security. Bluetooth
protocols are briefly described in Section 2.3
2.1 Bluetooth Architecture
Connection types define the possible ways Bluetooth
devices can exchange data. Bluetooth has three connection
types: ACL (Asynchronous Connection-Less), SCO
(Synchronous Connection-Oriented) and eSCO. ACL links
are for symmetric (maximum of 1306.9 kb/s for both
directions) or asymmetric (maximum of 2178.1 kb/s for send
and 177.1 kb/s for receive) data transfer. Retransmission of
packets is used to ensure integrity of data. SCO links are
symmetric (maximum of 64 kb/s for both directions) and they
are used for transferring realtime two-way voice.
Retransmission of voice packets is not used. Therefore, when
the channel BER is high, voice can be distorted. eSCO links
are also symmetric (maximum of 864 kb/s for both directions)
and they are used for transferring realtime two-way voice.
Retransmission of packets is used to ensure the integrity of
data (voice). Because retransmission of packets is used, eSCO
links can also carry data packets, but they are mainly used for
realtime two-way voice. Only Bluetooth 1.2 or 2.0+EDR
devices can use eSCO links, but SCO links must also be
supported to provide backward-compatibility. Bluetooth
devices that communicate with each other form a piconet. The
device that initiates a connection is the piconet master. One
piconet can have maximum of seven active slave devices and
one master device. All communication within a piconet goes
through the piconet master. The clock of the piconet master
and frequency hopping information are used to synchronize
the piconet slaves with the master. Two or more piconets
together form a scatternet, which can be used to
eliminate Bluetooth range restrictions. Scatternet
environment requires that different piconets must have a
common device, so-called scatternet member, to relay data
between the piconets. [7] [8] [9].
The design goals for Bluetooth technology have been
simplicity, compatibility, inexpensive and compact
microchips, fast data transfer, globality, secure
communication, and low power consumption. Simplicity
means that a Bluetooth device must be as easy as possible to
use for a user. Compatibility means manufacturer-
independent interoperability between different Bluetooth
devices, and it also means backward-compatibility with older
Bluetooth versions. Bluetooth microchips are also very
compact (roughly 5 mm × 5 mm of size) and cheap (roughly
2.50 dollars per microchip [Blu06d, Tan06]). The latest
public version of Bluetooth specification, Bluetooth
2.0+EDR, supports data rates up to 3 Mb/s. The future
version of Bluetooth specification (Seattle) is expected to
provide data rates up to 480 Mb/s. Globality means that
Bluetooth can be used all over the world using the same free
ISM-band. Bluetooth has built-in security measures at the link
level to provide the secure communication for the piconet.
Bluetooth microchips have also low power consumption and
therefore they are widely used in many different kinds of
mobile devices. [17][19]
2.2 Bluetooth Security
This section provides Bluetooth specifications to illustrate
their limitations and provide a foundation for some of the
security recommendations A high-level example of the
scope of the security for the Bluetooth radio path is depicted
in Figure 2. In this example, Bluetooth security is provided
only between the mobile phone and the laptop computer,
while IEEE 802.11 security protects the wireless local area
network link between the laptop and the IEEE 802.11 AP.
However, the communications on the wired network are not
protected by Bluetooth or IEEE 802.11 security capabilities.
End-to-end security is not possible without using higher-layer
security solutions in addition to the security features included
in the Bluetooth specification and IEEE 802.11 standards. [2]
The following are the three basic security services specified
in the Bluetooth standard:
Authentication: verifying the identity of communicating
devices. User authentication is not provided natively by
Bluetooth.
Confidentiality: preventing information compromise caused
by eavesdropping by ensuring that only authorized devices
can access and view data.
Authorization: allowing the control of resources by ensuring
that a device is authorized to use a service before permitting it
to do so.
The three security services offered by Bluetooth and details
about the modes of security are described below. Bluetooth
does not address other security services such as audit and
non-repudiation; if such services are needed, they must be
provided through additional means.
Figure1 Bluetooth Air-Interface Security
2.2.1 Authentication
The Bluetooth device authentication procedure is in
the form of a challenge-response scheme. Each device
interacting in an authentication procedure is referred to as
Laptop
Work
station
Printer
Switch
Server
IEEE
802.11
security
Cellpho
ne
Bluetooth Security

82
either the claimant or the verifier.[3] The claimant is the
device attempting to prove its identity, and the verifier is the
device validating the identity of the claimant. The challenge-
response protocol validates devices by verifying the
knowledge of a secret key—the Bluetooth link key. The
challenge-response verification scheme is depicted in Figure
2
The verifier transmits a 128-bit random challenge
(AU_RAND) to the claimant. The claimant uses the E1
algorithm to compute an authentication response using his
unique 48-bit Bluetooth device address (BD_ADDR), the link
key, and AU_RAND as inputs. The verifier performs the
same computation. Only the 32 most significant bits of the E
output are used for authentication purposes. The remaining
96 bits of the 128-bit output are known as the Authenticated
Ciphering Offset (ACO) value, which will be used later to
create the Bluetooth encryption key. The claimant returns the
most significant 32 bits of the E1 output as the computed
response, SRES, to the verifier. The verifier compares the
SRES from the claimant with the value that it computed. If
the two 32-bit values are equal, the authentication is
considered successful. If the two 32-bit values are not equal,
the authentication has failed. Performing these steps once
accomplishes one-way authentication. The Bluetooth
standard allows both one-way and mutual authentication to be
performed. For mutual authentication, the above process is
repeated with the verifier and claimant switching roles. [20]
Figure 2 Bluetooth Authentication
2.2.2 Confidentiality
In addition to the Security Modes, Bluetooth provides a
separate confidentiality service to thwart eavesdropping
attempts on the payloads of the packets exchanged between
Bluetooth devices. Bluetooth has three Encryption Modes,
but only two of them actually provide confidentiality. The
modes are as follows:
Encryption Mode 1—No encryption is performed on any
traffic.
Encryption Mode 2—individually addressed traffic is
encrypted using encryption keys based on individual link
keys; broadcast traffic is not encrypted.
Encryption Mode 3—All traffic is encrypted using an
encryption key based on the master link key. Encryption
Modes 2 and 3 use the same encryption mechanism
2.3 Bluetooth protocols
Bluetooth protocol stack is illustrated in Figure 2.
Protocols below HCI (Host Controller Interface) are built-in
to the Bluetooth microchip and protocols above HCI are
located as a part of the host device's software package. HCI is
needed between the hardware and software protocols. The
purpose of HCI is to enable manufacturer-independent
combining of Bluetooth chips (Host Controller) and the actual
host device. HCI takes care of security communication
between the host and Bluetooth module. [3]
Figure 3. Bluetooth protocol stack
Baseband and LMP (Link Manager Protocol) together enable
the physical RF connection. LC (Link Controller) is a state
machine that defines the current state of Bluetooth
device. Bluetooth device can be, for example, in low-
power mode for saving batteries, in the connected state
for normal piconet operation, or in the paging state for master
to bring new slaves to the piconet. LC has pseudorandom
number generation capability, the methods for managing
security keys, and capability for providing the needed
mathematical operations for authentication and encryption.
LM (Link Manager) acts as a liaison between the
application and the LC on the local device, and it also
communicates with the remote LM via PDUs (Protocol Data
Units) using the LMP, i.e. the LM communicates with three
different entities during a Bluetooth session: the local host
through HCI, the local LC (local operations), and the
Bluetooth Device 1
(Claimant)
Bluetooth Device 2
(Verifier)
Radio Interface
E1
Algorith
m
Link
Key
Authentication
Failed
Link
Key
Random Number Generator
Authentication
Successful
E1
Algorithm
=?
BD_ADDR
AU_RAND
Device address
AU_RAND
ACO
Yes No
ACO

83
remote LM (link configuration, link information, and link
management operations). The PDU is acknowledged at the
Baseband level, but it is acted upon by the LM. The local LM
usually resides on the Bluetooth module as a complete host-
module implementation. The remote LM can be defined as
the LM at the other end of the Bluetooth link. LM has also
several commands for handling security issues.
SCO and eSCO links are used for transferring realtime
two-way voice (see Section 2.1). They are established directly
from the Baseband level, so overhead of upper layer protocols
is not causing any delays for realtime two-way voice
connections.L2CAP (Logical Link Control and Adaptation
Protocol) is a software module that normally resides on the
host. It fits upper layer protocols to the Baseband, i.e. it acts
as a conduit for data on the ACL link between Baseband and
host applications. L2CAP also offers CO (Connection-
Oriented; from master to one slave and from slave to
master) and CL (Connection-Less; from master to multiple
slaves) services, and it is defined only for ACL links. Lower
layer protocols do not have to know how layers above
L2CAP work and vice versa. L2CAP can initiate security
procedures when a CO or a CL channel connection attempt is
made.
SDP (Service Discovery Protocol) is used to find the
services of Bluetooth devices in the range. RFCOMM (Radio
Frequency Communication) emulates serial ports over
L2CAP, and therefore it is possible to use existing serial port
applications via Bluetooth. OBEX (Object Exchange
Protocol) is used to exchange objects, such as calendar notes,
business cards and data files, between devices by using the
client-server model.
TCS (Telephony Control protocol Specification) binary
defines the call control signalling for the
establishment/release of speech and data calls between
Bluetooth devices. It also provides functionality for
exchanging signalling information that is unrelated to
ongoing calls. Many AT commands are also supported for
transmitting control signals for telephony control.[4]
BNEP (Bluetooth Network Encapsulation Protocol) is
used to provide networking capabilities for Bluetooth devices.
It allows that IP (Internet Protocol) packets can be carried in
the payload of L2CAP packets. IP is a network layer protocol
in the TCP/IP (Transmission Control Protocol / Internet
Protocol) protocol suite. It contains both addressing
information and some control information to enable routing
of packets. TCP is one of the transport layer core protocols
used in the TCP/IP protocol suite. It provides reliable
transmission of data in IP network. UDP (User Datagram
Protocol) is also one of the transport layer core protocols used
in the TCP/IP protocol suite. It provides unreliable
transmission of data in IP network, i.e. it does not provide
reliability, flow-control, or error-recovery functions to IP.
PPP (Point- to-Point Protocol) can also be used to provide
TCP/IP networking capabilities for Bluetooth devices, but it
is slower, i.e. it works over RFCOMM while BNEP works
directly over L2CAP, and therefore it is rarely used anymore.
3. Description of SAFER Plus Algorithm
The SAFER+ (Secure And Fast Encryption Routine)
algorithm is based on the existing SAFER family of ciphers,
which comprises the ciphers SAFER K-64, SAFER K-128,
SAFER SK-128. All algorithms are byte-oriented block
encryption algorithms, which are characterized by the
following two properties. First, they use a non-orthodox
linear transformation, which, is called Pseudo-Hadamard-
Transformation (PHT) for the desired diffusion, and second,
they use additive constant factors (Bias vectors) in the
scheduling for weak keys avoidance. [5]
It consists of two main units: the encryption data path
and the key-scheduling unit. The key-scheduling unit allows
on-the-fly computation of the round keys. To reduce the
silicon area, we used eight loops of a key scheduling single-
round implementation. Round keys are applied in parallel in
the encryption data path. The full Safer+ algorithm execution
requires eight loops of the single round. We chose the single-
round hardware implementation solution because, with this
minimum silicon area, we could achieve the required
throughput. The encryption data path’s first component is an
input register, which combines the plaintext and the feedback
data produced in the previous round. The input register feeds
the afer+ single round.
Figure.4 Safer + Implementation
K17
K2r-
/
Key
K
E
Y
S
C
H
E
D
U
L
I
N
G
Input Register
MUX
Key Odd
Addition
Safer Plus Single
round
Key Odd Addition
Output Register
Round
Keys
Round
key
128 Plain text
clock
When Sel=0
When Sel=1
F
E
E
D
B
A
C
K
D
A
T
A
Encryption
Data path 128
Cipher text
Reset

84
3.1 SAFER + Single round
A Safer+ single round has four subunits:
• The mixed XOR/addition subunit, which combines
data with the appropriate round sub key K2r–1.
• The non-linear layer (use of the non-linear functions
e and l). The e function is implemented as y = 45x in
GF(257), except that 45128 = 0. The l function is
implemented as y = log45(x) in GF(257), except that
log45(0) = 128.
• The mixed addition/XOR subunit, which combines
data with the round sub key K2r
• The four linear Pseudo-Hadamard Transformation
layers, connected through an “Armenian Shuffle”
permutation.
Figure5. SAFER+ single round
The implementation of the non-linear layer using a data-
mapping component that produces the X1 and X2 bytes is
done. These bytes are the input of the non-linear functions e
and l. During one round, we execute e and l eight times. This
design significantly reduces the required silicon area. Each
function is implemented using 256 bytes of ROM.
3.2 PHT Implementation
The design of PHT element is shown in Fig.6: The PHT
Implementation Multiplication by 2 can be achieved by one
bit left wired shift.
Figure 6 Psuedo Hadamard Transform
Out1=2 in1+in2 (1)
Out2=in1+in2 (2)
the four linear PHT layers connected through the
permutations. The permutation boxes show how input byte
indices are mapped into the output byte indices. Thus,
position 0 (leftmost) is mapped on position 8; position 1 is
mapped on position 11, etc.
4. Proposed SAFER Plus Algorithm
The Existing SAFER+ algorithm is modified to provide
higher data throughput and frequency. The modified SAFER+
algorithm has three modifications when compared to the
existing one.
(i) Rotation block is introduced between every
round. Rotation is towards left for encryption
and towards right for decryption
(ii) The input of round 1 and the output of round 2
are Xor/Add Modulo 16 byte-by-byte to form
the input of round 3. Similarly the input of
round 5 and the output of round 6 are Xor/Add
Modulo 16 byte-by-byte to form the input of
round 7.
(iii) Instead of PHT layer, Fast Walsh Hadamard
Transform (FWHT) is used.
The Encryption and the Decryption block diagrams are given
in the figure7 and figure 8.
Figure 8 Proposed SAFER+ for encryption
X
+ +
SHL 1
X 2 8 8
Out 1
Out 2
8
In 2
8
8 8
In 1
8

85
Figure 9 Proposed SAFER+ for Decryption
The proposed work is to replace the Pseudo Hadamard
Transform by Fast Walsh Hadamard transform.
Figure 10 Proposed SAFER+ single round
Figure 10 shows the proposed SAFER+ single round
architecture. In this, fast algorithms for Walsh Hadamard
Transform on sliding windows are used to implement pattern
matching most efficiently instead of PHT. The computational
requirement of the proposed algorithm is about 1.5 additions
per projection vector per sample which is the lowest among
existing fast algorithms for Walsh Hadamard Transform on
sliding windows.
4.1 Fast Algorithm for WHT
As any orthogonal (unitary) matrix can be used to define an
orthogonal (unitary) transform, we define a Walsh-Hadamard
transform of Hadamard order (WHTh) as



=
=
Hx
x
Hx
X
These are the forward and inverse transform pair.
[ ]T
1]
N
x[1],...x[
x[0],
x −
=
and
[ ]T
1]
N
X[1],...X[
X[0],
X −
= are the signal and spectrum
vectors, respectively. The Kth element of the transform can
also be written as
∏
∑ ∑
−
=
= =
−
=
=
1
0
1
-
N
0
m
1
-
N
0
m
)
1
(
x[m]
m]x[m]
h[k,
X[k]
n
i
k
m i
i
The complexity of WHT is O (N) 2.
Similar to FFT algorithm,
Fast WHT algorithm with complexity of O (Nlog2N) are
derived assume n=3 and N=2n
=8 in the following derivation.
An N=8 point WHTh of signal ]
[m
x is defined as
This equation can be separated into two parts [13]. The first
half of the X vector can be obtained as
-- (1)
Where
-- (2)
The second half of the X vector can be obtained as

86
-- (3)
where
-- (4)
Converting a WHT of size N=8 into two WHT of size N/2=4.
Continuing this process recursively, we can rewrite Eq. (1) as
the following (similar process for Eq. (3))
-- (5)
where
-- (6)
The second half is
-- (7)
where
-- (8)
X (4) through X (7) of the second half can be obtained
-- (9)
and
-- (10)
Summarizing the above steps of Equations (2), (4), (6), (8),
(9) and (10), we get the Fast WHT algorithm as illustrated
below.
Figure 11 Fast WHT algorithm
5. Results
Various existing algorithms are analyzed and compared with
the proposed algorithm based on the parameters such as
encryption frequency, Data throughput and security level and
the results are shown in the bar charts.
99
88.33
78.08
65.44
37.19
0
20
40
60
80
100
120
Triple DES Pipelined AES ECDH Safer Plus Efficient
Proposed Safer
Plus
ALGORITHM
ENCRYPTION
TIME(ms)
Figure 12 Encryption Time Vs Various Algorithms
Based on the analysis, the modified Safer Plus algorithm
required minimum encryption time and maximum encryption
frequency when compared to all the existing algorithms due
to the inclusion of FWHT instead of PHT layer as shown in
Figure 12 and Figure 13.
10.1
12.56
14.82
16.63
26.88
0
5
10
15
20
25
30
Triple DES Pipelined
AES
ECDH Safer Plus Efficient
Proposed
Safer Plus
ALGORITHM
ENCRYPTION
FREQUENCY(Kilo
Hz)
Figure 13 Encryption Frequency Vs Various Algorithms
The number of hits required to attack the various algorithms
is also compared and shown in Figure14. The security level is
much enhanced for the algorithm proposed since the number
of hits is found to be maximum due to the introduction of the
rotation block between every round.
COMPARISON
943999
688787 722519
873736
1605882
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
1800000
Proposed Safer
Plus
ALGORITHM
HITS
COUNT
FOR
ATTACKS
Figure 14 No. of Hit counts Vs Various algorithms

87
46.63
52.68
59.19
67.11
124.14
0
20
40
60
80
100
120
140
Proposed
Safer Plus
ALGORITHM
DATA
THROUGHPUT(Bytes)
Figure 15 Data throughput Vs various algorithm
Figure 15 shows that modified Safer plus algorithm has
higher data throughput comparatively because the input of
round 1 and the output of round 2 are Xor/Add operation to
form the input of round 3.
0
20
40
60
80
100
120
140
Triple DES Pipelined AES ECDH Safer Plus Efficient Proposed
Safer Plus
ALGORITHM
C
O
M
P
A
R
I
S
O
N
ENCRYPTION TIME(ms)
ENCRYPTION FREQUENCT(Kilo Hz)
DATA THROUGHPUT(Bytes)
Figure 16 Encryption time, Encryption frequency and data
throughput Vs various algorithms
Figure16 consolidates the performance of the proposed
algorithm. It is observed that the modified Safer Plus is the
best.
6. Conclusion
In this paper, a modified SAFER plus algorithm is proposed
by replacing PH transform with FWH transform and
introducing a rotation block for every round. The existing
security algorithms are compared with the proposed Safer
Plus algorithm. The entire design is captured in J2ME. The
efficiency of the algorithm is evaluated by the analysis of
parameters like encryption time, encryption frequency, and
data throughput and security level. On comparison, the
modified Safer plus algorithm proved to be better for
implementation in Bluetooth devices than the existing
algorithms.
7. References
[1] Paraskevas kitos, Nicolas sklavos, Kyriakos
Papadomanolakis and Odysseas Koufopavlou university of
patras, Greece,” Hardware Implementation of Bluetooth
Security” IEEE CS and IEEE Communications Society -
January to March 2003. pp. 21 to 29.
[2] Karen Scarfone John Padgette, “Guide to Bluetooth security “
National Institute of standards and technology Special Publication
800-121, U.S. Department of Commerce 43 pages.
[3] Vainio, Juha T. “Bluetooth Security,” Helsinki University of
Technology, 25 May 2000
[4 ] Gyongsu Lee, ”Bluetooth Security Implementation based on
Software Oriented Hardware-Software Partition” IEEE journal
2005. pp. 2070-2074.
[5] Kardach, James, “Bluetooth Architecture Overview,” Intel
Technology Journal, 2000
[6] Jyrki Oraskari, "Bluetooth versus wlan ieee 802.11x",
Helsinki university of technology, october, 2001.
[7] A. Laurie and B.Laurie. serious flaws in blue tooth security
lead to disclosure of personal data. http://bluestumbler.com.
[8] Brent A.Miller And Chatschik Bisdikian “Bluetooth revealed”
– low price edition
[9] Wikipedia.org, “Bluetooth,” Wikipedia.org, 5 March 2005,
http://en.wikipedia.org/wiki/Bluetooth (21 February 2005)
[10] Vrije Universiteit Brussel, “Bluetooth security” phd thesis
December 2004
[11] Keijo M.J. Haataja Licentiate Thesis January 2007
University of Kuopio
[12] J. L. Massey, “On the Optimality of SAFER+ Diffusion”,
Second Advanced Encryption Standard Candidate Conference
(AES2), Rome, Italy, March 22-23 online available at
http://csrc.nist.gov/encryption/aes/round1/conf2/aes2conf.htm.
[13] Wanli Ouyang, W.K. Cham,”Fast Algorithm for Walsh
Hadamard Transform on Sliding Windows” IEEE
TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE
INTELLIGENCE, MANUSCRIPT ID TPAMI-2008-06-0328
[14] NIST: Advanced Encryption Standard (AES) The Federal
Information Processing Standards Publication 197. NIST,
November 26, 2001.
http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
(20.9.2006)
[15] NIST: Recommendation for the Triple Data Encryption
Algorithm (TDEA) Block Cipher. NIST, May 2004.
http://csrc.nist.gov/publications/nistpubs/800-67/SP800-67.pdf
(19.9.2006)
[16] NIST: Data Encryption Standard (DES) The Federal
Information Processing Standards Publication 46-3. NIST,
October 1999. http://www.cerberussystems.
com/INFOSEC/stds/fip46-3.htm (19.9.2006)
[17]AlfonsoDeGregorio. Cryptographic Key ReliableLifetimes:
Bounding the Risk of Key Exposure in the Presence of Faults. In
Fault Diagnosis and Tolerance in Cryptography, volume 4236 of
LNCS, pages 144–158. Springer, 2006.
[18] ARC Electronics (n.d.). DSSS and FHSS - Spread Spectrum
modem. Retrieved March 24, 2004 from, Web
site:http://www.arcelect.com/DSSS_FHSS-spead_spectrum.htm

88
D.Sharmila is presently working as
Associate Professor, Department of
ECE, Bannari Amman Institute of
Technology, Sathyamangalam. She
received B.E.(ECE) and M.E.
(Applied Electronics) from Kongu
Engineering College, Perundurai. She
is now pursuing Phd in Wireless
Security. She has 14 years of teaching
experience and has guided several UG and PG projects. She is
a life member of ISTE and Associate member of IE. Her area
of interests are Wireless Security, Low power VLSI, Adhoc
networks. She has published 4 International and National
Journals and presented 20 research papers in International and
National Conferences.
Dr.R. Neelaveni is presently working
as Assistant Professor, Department of
EEE, PSG College of Technology,
Coimbatore. She has a Bachelor’s
degree in ECE, a Master’s degree in
Applied Electronics and PhD in
Biomedical Instrumentation. She has
19 years of teaching experience and
has guided many UG and PG projects. Her research and
teaching interests includes Applied Electronics, Analog
VLSI, Computer Networks, and Biomedical Engineering. She
is a Life member of Indian Society for Technical Education
(ISTE).She has published several research papers in national
Journals and Conferences.

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