Text hiding in text using invisible character

International Journal of Electrical and Computer Engineering (IJECE)
Vol. 10, No. 4, August 2020, pp. 3550~3557
ISSN: 2088-8708, DOI: 10.11591/ijece.v10i4.pp3550-3557  3550
Journal homepage: http://ijece.iaescore.com/index.php/IJECE
Text hiding in text using invisible character
Nada Abdul Aziz Mustafa
College of Languages, University of Baghdad, Iraq
Article Info ABSTRACT
Article history:
Received Jun 24, 2019
Revised Jan 29, 2020
Accepted Feb 10, 2020
Steganography can be defined as the art and science of hiding information in
the data that could be read by computer. This science cannot recognize
stego-cover and the original one whether by eye or by computer when seeing
the statistical samples. This paper presents a new method to hide text in text
characters. The systematic method uses the structure of invisible character to
hide and extract secret texts. The creation of secret message comprises four
main stages such using the letter from the original message, selecting
the suitable cover text, dividing the cover text into blocks, hiding the secret
text using the invisible character and comparing the cover-text and stego-
object. This study uses an invisible character (white space) position of in
the cover text that used to hide the the secrete sender masseges.
The experiments results show that the suggested method presents highly
secret due to use the multi-level of complexity to avoid the attackers.
Keywords:
Invisible character
Steganography
Stego-cover
Stego-object
Stego-text
Copyright © 2020 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Nada Abdul Aziz Mustafa,
College of Languages,
University of Baghdad,
Karrada, Al-Jadriya, Baghdad, Iraq.
Email: nada@colang.uobaghdad.edu.iq
1. INTRODUCTION
Text steganography technique is applied for saving privacy and originality of text-based documents.
Thereby, text steganography connsiders as a challenging mission that tenuous adjustment in text file can be
specified. Invisible character technique is used to hide the text into text or image without anyone can be seen
the hidden processing [1]. There are different techniques like steganography, cryptography, coding, etc have
been utilized. Currently, steganography is commonly used to hide text in text. Steganography implies
“covered writing” in Greek as well as it considers the flag of communicating in a hidden style [2].
In view of this digital steganography conceals even the evidence of encrypted messaging [3].
Steganography is one of the oldest arts that people were eager to have since they started communication with
each other [4]. Many methods have been used to hide information by using the recorder with tales of
steganography and cryptography through times of war or peace [5]. Moreover, steganography is the art and
science which hide information in any computer readable data in a way that a stego-object should be not
distinguishable from origin cover neither by a human nor by computer looking for statistical pattern [6].
While steganography is an early topic, the current preparation of it arrives via the prisoner’s issues suggested
by [7], Alice and Bob are the two prisoners, they communicate via secret to access an escape strategy.
Several message sent via a warden called Eve that may toss the private limitation when it suspects any type
of secret message [8]. Thus, the secret letter provides the natural of steganography to realize the hiding
information between them. They used a warden method to test the whole messages replaced between them
may either be direct or indirect. A direct warden method attempts for adjusting the message and the supposed
covered data calculatingly via eliminating the data while an indirect warden method that is used to take
the meaning of covered message, updates the others and lets the message to permit [9]. A supposition may be
completed based on this typical when both the sender and receiver will share particular public secret data
then the conforming steganography procedure is recognized as then the secret key steganography where

Int J Elec & Comp Eng ISSN: 2088-8708 
Text hiding in text using invisible character (Nada Abdul Aziz Mustafa)
3551
as pure steganography proceeds that there is nothing previous data mutual by sender and receiver.
While the public key of the receiver is identified to the sender, the steganographic procedure is named public
key steganography [10].
2. RELATED WORK
Steganography suppose the opposition may capture the cover, nevertheless may be not observe any
data further the original cover satisfied [11]. The data is covered and can have no supplementary safety
further the real letter embedding [12]. A role principle for performance measurement of a steganographic
structure is the statistical hiddenness of the secret data [13]. Digital text image have higher grade of
redundancy and hence the most appropriate for steganography. There exist many steganographic methods
that allow hiding secret data in text image having their own pros and cons. Least Significant Bit modification
(LSB) method is the commonly used steganographic procedure that uses the information at least significant
bits of a text image are random noise and shifting them does not shift the perceptual worth of the text images.
Moreover, LSB depend on approaches may be either LSB Matching or LSB Replacement where the former
swaps the LSB of the pixels with the communication to be sent and the advanced increment/decrement
the pixels arbitrarily with secret bits [14]. Hiding information within places appears to be potential as human
hardly may distinguish about the being of the hidden bits. Presently, operation of whitespaces appears useful
and has its possible in information hiding due to whitespaces seem in a document more than the occurrence
of words. It is uniform a benefit when anyone will distinguish that a blank piece of text is really role secret
information [15]. In addition, a new technique of text steganography was presented. Their proposed
algorithm uses text media to embed their secret text file depending on a dictionary. This dictionary contains
English. Words sorted in alphabetical order to be selected by user in order to build the cover text [16].
The statistical properties of dithered imagery was used. With this method, the information bits to be
concealed control the dot patterns of the ordered dither pixel. The system adapts two kilobytes of hidden data
for a bit level (256*256) images, compliant a volume of or data-hiding ratio of one data bit to four cover
image bits [17]. In the same context, the term steganography factually incomes “covered writing”
as stemmed from Greek. It can be defined as the art and science of communication in a way that it used to
hide the actuality of communication. A general steganography system is shown in Figure 1 as given by [18]
in the following:
In this section, it is explained the results of research and at the same time is given
the comprehensive discussion. Results can be presented in figures, graphs, tables and others that make
the reader understand easily [2, 5]. The discussion can be made in several sub-chapters.
- Embedded <data-type>: Something to be hidden in something else.
- Stego-<data-type>: The output of the hiding process, something that has the embedded.
- Cover <data-type>: An input with “original” form of the stego-message. In some applications such
a cover message is given from the outside, it can be chosen during the hiding process. The letter
is represented by the dashed extension to the inner hiding process.
- Stego-object: the output from stego-system, something hidden in it.
- Stego-key: Extra secret information can be hidden in the stego-system the same key is typically required
to extract the embedded message again.
- The process of hiding the embedded message is called Embedding.
- Getting the embedded message out of the stego-message again is called Extracting [19].
Figure 1. General steganography system

 ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 4, August 2020 : 3550 - 3557
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3. PROPOSED SYSTEM
The systematic approach is used invisible character that can be classified into three chief stages:
Hiding (secret) text in (cover) text using the invisible character (hiding keys), extracting the (original) text by
using the hidden keys and performance evaluation as shown in Figure 2.
Figure 2. Flow chart of the systematic approach
3.1. Hiding text in text
Below the steps for hiding the (secret) text in (innocent) text. Choose any text with enough size
as innocent text to use it as cover text. The hide procedures are as follows:
- Divide the (cover-Text) to blocks (number of characters or bytes).
- In each block hides one character of the secret message (Text).
(Note: both of them cover and secret message characters are represented in ASCII code).
- The calculations of each block length is:
Block length =
𝑁𝑜.𝑜𝑓 𝑐ℎ𝑎𝑟𝑎𝑐𝑡𝑒𝑟𝑠 𝑖𝑛 𝑐𝑜𝑣𝑒𝑟−𝑡𝑒𝑥𝑡
𝑁𝑜.𝑜𝑓 𝑐ℎ𝑎𝑟𝑎𝑐𝑡𝑒𝑟𝑠 𝑖𝑛 𝑠𝑒𝑐𝑟𝑒𝑡−𝑡𝑒𝑥𝑡
(Byte)
- From each block we leave two bytes (two from the beginning and at the end of the block) that will not be
used to hide the secret message. (Note: more than two bytes can be leaved to increase the hiding
capacity). Search the first block to find an identical (ASCII) value to that of the first secret message
character.
- If we found it then insert invisible character to the right of it to indicate the hidden character.
- Else, if we not found an identical (ASCII) value then we search again for the character that is either
greater than secret character (ASCII) value by (1,3,or 5) or less than secret character (ASCII) value
by (3 or 5); if we found one then insert an invisible character to the right of it.
- To indicate whether the character to the left of invisible character was identical increase, or decrease by
some value. The following protocol (depending on the two bytes that we left at the beginning and end
of the block).
- The comparison between the cover-text and steg-object doesn’t find any modification (before and after
hiding text) and it should be identical to prevent any drawn suspicion of the attackers existed into
innocent text as shown in Figure 3.

3553
Figure 3. Secret text in the top and the cover text at the bottom (before/after hiding text)
3.2. Hiding processing
The whole steps for each point is explained as follows:
- Insert invisible character at the end of the block to indicate an identical character value.
- Insert invisible character at the beginning of the block, means that the character value is increased by one.
- Insert invisible character after the first byte of the block means, that the character value is increased
by three.
- Insert invisible character after the second byte of the block, means that the character value is increased
by five.
- Insert invisible character before the first byte from the end of the block, means that the character value is
decreased by three.
- Insert invisible character before the byte before the second byte from the end of the block means that
the character value is decreased by five.
For each block repeats the steps from (E to H) until all secret characters are hidden Figure 4,
The flow chart for hiding text in text as shown Figure 5.
When I: is the invisible character and C: is any value (ASCII).
Figure 4. Hiding text in text using invisible character

 ISSN: 2088-8708
3554
Figure 5. Flow chart to hide text in text f: secret message file, f1: cover file, b: byte,
A: Array of character BL: Block Length
While the algorithm for hiding (secret) text in (innocent) text as follows:
Start
Loop: while (not Eof stego-object file) do
Begin
Blockread (stego-object file, b, Block length)
Blockread (secret file, c, 1)
Loop: Repeat i=3;
If C=(b [i] or (b [i]+1) or (b [i]+3) or (b [i]+5 or (b [i]-3 or (b[i]-5)) then
Begin
b [i+1] = Invisible character;
(b[1]or b[2] or b[3] or b[block length] or b[block length-1]or b[block length-2] ) = invisible
character {according to above}
Found = true;
End;
Until (found)
3.3. Extracting stage
The extracting stage is intended to recover the hidden text from the stego-object. Extracting stage
includes extracting secret-text from the stego-object text that it is indicated as the opposites of hide procedure
algorithms [20]. The whole algorithm is used to extract the secret text as shown in details as bellows:
Start
Blockread (stego-object file, b, 6o)
j= b [1]
No. Of part = b [1+j]
No. Of Byte in each part = b [1+2j] and b [2+2j]
No. Of byte in last part = b [1+3J]
Length of text block = b [1+4j]
Loop: repeat
Loop: For i= 1 to (No. of byte hide in each part) NS
Block read (stego-object, c, 1)
If (i =A [i]) then
Block write (extract file, c, 1)
Until (No. Of parts)

3555
4. EXPERIMENTAL RESULT
Prefect steganography is when gets stego-object similar to original innocent text by both
perceptually and computer reading. This may be impossible to reach. For experimental results, it was found
that the cover when it changes to stego-object gives the closest criteria to original cover.
There are two different schemes that is used to give an idea if these are a hidden message or not:
- Blind scheme. One is the process that should be possible without the original cover called
(blind schemes) which need a high technique to discover and detect the hidden message [21].
- Escrow scheme. The second scheme where the original cover signal is needed to reveal the hidden
information called (escrow scheme).
The second scheme compare between the origin cover and stego-object and cheek if there are any
different. The second scheme is used to evaluate the performance evaluation by taking several criteria that it
was used to evaluate the covers [22].
4.1. Avoiding stego-analysis
The developed algorithm for information hiding in this study was implemented taking into account
stego-analysis. This algorithm includes some features that may help in avoiding stego-analysis attacks.
These features are:
- Using private stego-object to prevent drawing suspicion about the hidden information. A comparison
between stego-object and the innocent cover may be inefficient, and any modification on the original
cover may be imperceptible [23]. Figure 6 explain comparing between the text-cover and its
corresponding stego-text. From the result of comparing between the innocent text and the stego-object,
it observed that anyone cannot see any modification in stego-object.
- Using multiple stages of encryption to prevent the extraction of the hidden information as most as
possible [24], i.e. if there is any suspicion about the hidden information, they cannot be extracted.
Hiding the secret text in innocent text at first by using the method of the hypertext markup language
(HTML) files. The files utilized to convey the information meanwhile adding space, tabs, and “invisible”
character. For example, hiding an English secret text Figure 7 in an innocent text Figure 8, stego-object with
hidden information, and without drawn suspicion by using image (1), while Figure 9 explains the evaluation
results with hidden information when using stego-object.
From the experimental results, it can clearly observed that the comparison result of performance
evaluation (average, variant, energy, entropy, similarity, secrecy and SNR) between the cover-text and
the stego-object is a little bit different that it indicate anyone can not seen the hidden operations. The average
value of the proposed technique carried out better performance with an increase of 15%% compared to
the average value of of energy and sensitivity [25] using the BMP image steganography.
Figure 6. Comparison between the origin (text-cover) and its corresponding stego-object text
ORIGIN TEXT STEGO TEXT

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Figure 7. English text (secret message), which will
be hidden in text
Figure 8. The innocent text cover, in which
information will be hidden
Figure 9. Comparison between text-cover and stego-object text depends on the evaluation metrics
5. CONCLUSION
Hiding text in text using invisible character provides an efficient method. This study was performed
in three stages, hide text in text, extract the secret text from the stego-object text and evaluation metrics.
The hide procedure can perform a security operation in order to hide the secret text. The extract stage
algorithm reverses the hide procedure effects in order to extract the hidden text. Moreover, using public
stego-object to prevent knowing the original cover, in order to prevent any comparison between the innocent
cover and stego-object. There are many levels of complexity with the proposed system, which prevent
attacker to reach the secret message. Consequently, the capability to increase the capacity of hiding. Proposed
system depends on modifying (2-3) bit of secret message. Also can instead of represent each character with
(8-bit) can represent it with (5-bit) (no. of character are 26) and hence (3-bit) save can accomplished.
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BIOGRAPHY OF AUTHOR
Nada Abdul Aziz Mustafa, her born at September 1st
1966, Scientific Degree: Msc. in
computer science. Research Projects in The Felid of Specialization to The Environment and
Society or the Development of Education: (a) Design and Implementation: Proposed
Encoding and Hiding Texts in an Image, University of Sulymaina, 2010. (b) Utilizing
Computers in Teaching, University of Baghdad, Conference, 2010. (c) A proposed
Technique for Information Hiding Based on DCT, IJACT, South Korea, 2011.
(d) Encryption a text using affine cipher and hiding it in the colored image by using
the Quantization stage, University of Mustansiriya, Conference, 2013. (e) Face detection
and the effect of contrast and brightness, JNIT, South Korea, 2014. (f) The Effect of
the Smoothing Filter on an Image Encrypted By the Blowfish Algorithm Then Hiding It in
A BMP Image, JNIT, South Korea, 2014.

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