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New Approach toward Data Hiding by Using AffineCipher and Least Significant Bit Algorithm

Fady MedhatAbdelrahman Soliman

Ahmed AbdelmegidOmar MobarakAmr MohamedAhmed Ragab

German University in CairoFaculty of Information Engineering and Technology

Communication Department

Information Theory, 2018

Fady Medhat Abdelrahman Soliman Ahmed Abdelmegid Omar Mobarak Amr Mohamed Ahmed Ragab (German University in Cairo)New Approach toward Data Hiding by Using Affine Cipher and Least Significant Bit AlgorithmInformation Theory, 2018 1 / 38

Outline

1 Introduction

2 Cryptography

3 Affine Cipher

4 Steganography

5 Least Significant Bit

6 Weakness in Cryptography and Steganography

7 Implementation

8 Results

9 Conclusion

10 References

Introduction

The development of internet now days can make people transfer dataeasily.

People can communicate with other by email, social media

Figure: 1

Introduction

The development of internet now days can make people transfer dataeasily.People can communicate with other by email, social media

Figure: 1

Introduction

The development of internet now days can make people transfer dataeasily.People can communicate with other by email, social media

Figure: 1

Introduction

Texts are the most object which people use to send message

Figure: 1

Introduction

Texts are the most object which people use to send message

Figure: 1Fady Medhat Abdelrahman Soliman Ahmed Abdelmegid Omar Mobarak Amr Mohamed Ahmed Ragab (German University in Cairo)New Approach toward Data Hiding by Using Affine Cipher and Least Significant Bit AlgorithmInformation Theory, 2018 4 / 38

Introduction

High security needed to be able to protect information and datanetwork system against attacks and destruction of hackers oreavesdropper

Figure: 1

Introduction

High security needed to be able to protect information and datanetwork system against attacks and destruction of hackers oreavesdropper

Figure: 1

Introduction

Due to data network system attacks, there are two algorithms thathelps in data security such as : Cryptology

Figure: 1

Introduction

Due to data network system attacks, there are two algorithms thathelps in data security such as : Cryptology

Figure: 1

Cryptography

History of Cryptography

Cryptography Greek word means secret writing Kryptos meansHidden, Graphein means writing is the mathematical scrambling ofdata into unreadable form to preserve confidentiality.

There are three eras in the history of Cryptography

The Manual era,The Mechanical era,The Modern era

Mechanical era refers to the invention of cipher machines.

The modern era of cryptography refers to computers

Cryptography

What is Cryptography ?

Cryptography is an art of Secret writing

Cryptography is the process of converting plaintext into ciphertext,thesecret message encrypted or scrambled by using algorithms,thealgorithms convert the secret message into a non readable

K refers to key

Figure: 1

Cryptography

What is Cryptography ?

Cryptography is an art of Secret writing

Cryptography is the process of converting plaintext into ciphertext,thesecret message encrypted or scrambled by using algorithms,thealgorithms convert the secret message into a non readable

K refers to key

Figure: 1

Cryptography

Need for Cryptography ?

Establishing a Secure communication

Fulfil the security goals.Preservation of Authentic informationSecure TransactionPrivacy.

Figure: 1

Cryptography

Establishing a Secure communicationFulfil the security goals.

Preservation of Authentic informationSecure TransactionPrivacy.

Figure: 1

Cryptography

Establishing a Secure communicationFulfil the security goals.Preservation of Authentic information

Secure TransactionPrivacy.

Figure: 1

Cryptography

Establishing a Secure communicationFulfil the security goals.Preservation of Authentic informationSecure Transaction

Privacy.

Figure: 1

Cryptography

Establishing a Secure communicationFulfil the security goals.Preservation of Authentic informationSecure TransactionPrivacy.

Figure: 1

Cryptography

Establishing a Secure communicationFulfil the security goals.Preservation of Authentic informationSecure TransactionPrivacy.

Figure: 1

Cryptography

Types of Cryptography ?

Symmetric ciphers are used to achieve cryptographic primitives.

Symmetric cryptography is divided into three subclasses: Classical,Mechanical and Modern Ciphers

Classical classified into a number of smaller subclasses: Substitutionand Transposition Ciphers

A monoalphabetic substitution cipher relies on a fixed replacementstructure such as:-The Caesar Cipher, The Atbash Cipher and TheAffine Cipher

Cryptography

Affine Cipher

In this approach , the affine cipher took place

Affine cipher uses modulo operation to transform the integer ofplaintext into the integer of ciphertext. The integer of cipher textcorresponds to ciphertext letter.

C = ((a ∗ P) + k)mod26 (1)

The parameters a and k are the key for this cipher and 26 is thelength of the alphabetic, C refers to ciphertext.

Figure: 1

Affine Cipher

In this approach , the affine cipher took placeAffine cipher uses modulo operation to transform the integer ofplaintext into the integer of ciphertext. The integer of cipher textcorresponds to ciphertext letter.

C = ((a ∗ P) + k)mod26 (1)

Figure: 1

Affine Cipher

C = ((a ∗ P) + k)mod26 (1)

Figure: 1

Affine Cipher

C = ((a ∗ P) + k)mod26 (1)

Figure: 1

Affine Cipher

C = ((a ∗ P) + k)mod26 (1)

Affine Cipher

For decryption process

P = a−1 ∗ (C − k)mod26 (2)

a is an integer which must be relatively prime to 26. In other words,great common divisor (a, 26) must be equal to 1

Multiplication inverse

a−1 = (((i ∗ 26) + 1)/key) (3)

,i is a counter.

Affine Cipher

For decryption process

P = a−1 ∗ (C − k)mod26 (2)

a is an integer which must be relatively prime to 26. In other words,great common divisor (a, 26) must be equal to 1

Multiplication inverse

a−1 = (((i ∗ 26) + 1)/key) (3)

,i is a counter.

Steganography

History of Steganography

The first recorded uses of steganography can be traced back to 440BC when Herodotus mentions two examples of steganography in hishistories

Ancient Greeks used wax tablets as reusable writing surfaces,sometimes used for shorthand.

Ancient Chinese wrote messages on fine silk, which was thencrunched into a tiny ball and covered in wax.

Special inks were important steganographic tools even during SecondWorldWar

Steganography

What is Steganography

Steganography is the art and science of writing hidden messages.

The message is hidden in cover object that could be media text,images, audio, or video.

Steganography has two processes which are embedded and extracting.

Embedding is use to hide data to cover object.

Extracting is use to get the data back.

Figure: 1

Steganography

Figure: 1

Steganography

Figure: 1

Steganography

Figure: 1

Steganography

Figure: 1

Steganography

Figure: 1

Steganography

Types of Steganography

Text Steganography.

Image Steganography.

Audio Steganography.

Video Steganography.

Protocol Steganography.

Steganography

Text Steganography.

Steganography

Text Steganography.

Steganography

Text Steganography.

Steganography

Text Steganography.

Steganography

Image Steganography

It is embedding the message in the intensity of the pixels directly.

Figure: 1

Steganography

Image Steganography

It is embedding the message in the intensity of the pixels directly.

Figure: 1

Least Significant Bit

It is an image steganography in which least significant bits of pixels ofthe image or the last bit pixels of image is replaced with data bitsfrom secret message.

Figure: 1

Least Significant Bit

It is an image steganography in which least significant bits of pixels ofthe image or the last bit pixels of image is replaced with data bitsfrom secret message.

Figure: 1

Weakness in Cryptography and Steganography

In cryptography, it can be broken by brute force algorithm ormathematical calculation.

In steganography, it could be attack by analyzing the pattern of stegoobject or statistical method.

Steganography and Cryptography alone is not sufficient.

Implementation

On this research, the combination of affine cipher and LSB helps thedata to be more secured

Figure: 1

Implementation

On this research, the combination of affine cipher and LSB helps thedata to be more secured

Implementation

Figure: 1

Implementation

For example to perform cryptography and steganography we are goingto make the whole algorithm on original word DRW.

BY using the equation of the affine cipher with key a=23 and k=7 onthe word DRW will be encrypted to YIT.

C = ((a x P) + k) mod 26

Then using the ascii code table to convert YIT to bits

Implementation

C = ((a x P) + k) mod 26

Implementation

C = ((a x P) + k) mod 26

Implementation

C = ((a x P) + k) mod 26

Implementation

Figure: 1

Implementation

Y=89=01011001

I=73=01001001

T=84=01010100

Implementation

Y=89=01011001

I=73=01001001

T=84=01010100

Implementation

Y=89=01011001

I=73=01001001

T=84=01010100

Implementation

After converting the cipher text to bits its time to combine it with thecover image using the LSB algorithm

Consider we have a cover image with RGB value as follows

Figure: 1

Implementation

After converting the cipher text to bits its time to combine it with thecover image using the LSB algorithmConsider we have a cover image with RGB value as follows

Figure: 1

Implementation

After converting the cipher text to bits its time to combine it with thecover image using the LSB algorithmConsider we have a cover image with RGB value as follows

Implementation

Convert the RGB values of image to binary number as follows

Figure: 1

Implementation

Convert the RGB values of image to binary number as follows

Implementation

Embed the cipher text to the RGB values , RGB values were changedas follows

Figure: 1

Implementation

Embed the cipher text to the RGB values , RGB values were changedas follows

Figure: 1

Implementation

The values of the stego image in decimals will be

Figure: 1

Implementation

The values of the stego image in decimals will be

Implementation

The message is fully encrypted using a combination between affinecipher and LSB

The receiver should know and use the same key to decrypt this imageand to get the original plan text

So now if the receiver has the stego image and want to know what isthe original message will start to extract the stego image then decryptthe cipher text

Implementation

To decrypt the stego image first it should change the RGB numbersto bits

Figure: 1

Implementation

To decrypt the stego image first it should change the RGB numbersto bits

Figure: 1

Implementation

Then taking the last bit of the stego object

the set of binary strings divided into 8 characters

The result of each 8 characters the binary is converted into ASCIIcharacters

The last bits of the stego image will be 01011001 01001001,01010100

Implementation

Converting the bits to ASCII Characters YIT.

Now after extracting the stego image we have to decrypt the ciphertext YIT

Using the decryption equation

P = a−1 ∗ (C − k)mod26 (4)

The plaintext obtained will be DRW

Implementation

P = a−1 ∗ (C − k)mod26 (4)

Implementation

P = a−1 ∗ (C − k)mod26 (4)

Implementation

P = a−1 ∗ (C − k)mod26 (4)

Results

The length of text is directly proportional to the time the encryptionor decryption

Figure: 1

Results

The length of text is directly proportional to the time the encryptionor decryption

Figure: 1

Results

Conclusion

LSB can only accomodate 1 bit for each component R, G or B so asto accommodate a 1 character (8 bit data), it takes 64 bits of thecover image. Caused by it then to hide the data that is needed, coverimage, measuring at least 8 x the size of the message.

The combination of affine cipher and the LSB can secure the dataproperly original message can be returned as the inherent quality ofthe original image and the epoch of the image that you inserted themessage nearly as insubstantial and indistinguishable

Conclusion

LSB can only accomodate 1 bit for each component R, G or B so asto accommodate a 1 character (8 bit data), it takes 64 bits of thecover image. Caused by it then to hide the data that is needed, coverimage, measuring at least 8 x the size of the message.

The combination of affine cipher and the LSB can secure the dataproperly original message can be returned as the inherent quality ofthe original image and the epoch of the image that you inserted themessage nearly as insubstantial and indistinguishable

References

JidagamVenkataKarthik, B.Venkateshwar Reddy, Authentication ofSecret Information in Image Steganography, International Journal ofLatest Trends in Engineering Technology, ISSN: 2278-621X, Vol.3(1), Sep 2013.

Shristi Mishra, Prateeksha Pandey A Review on SteganographyTechniques Using Cryptography, International Journal of AdvanceResearch In Science And Engineering, Vol. No.4, Special Issue (01),March 2015.

Y. Sazaki and R. S. Putra, ”Implementation of Affine TransformMethod and Advanced Hill Cipher for securing digital images,” 201610th International Conference on Telecommunication SystemsServices and Applications (TSSA), Denpasar, 2016, pp. 1-5. doi:10.1109/TSSA.2016.7871068.

References

Nurhayati and S. S. Ahmad, ”Steganography for inserting message ondigital image using least significant bit and AES cryptographicalgorithm,”2016 4th International Conference on Cyber and ITService Management, Bandung, 2016, pp. 1-6.doi:10.1109/CITSM.2016.7577468.

I.Venkata Sai Manoj, TKR College of Engg. Tech., Hyderabad, A.P.,International Journal of Computer Applications (0975 8887) Volume1 No. 12,2010.

References

Nurhayati and S. S. Ahmad, ”Steganography for inserting message ondigital image using least significant bit and AES cryptographicalgorithm,”2016 4th International Conference on Cyber and ITService Management, Bandung, 2016, pp. 1-6.doi:10.1109/CITSM.2016.7577468.

I.Venkata Sai Manoj, TKR College of Engg. Tech., Hyderabad, A.P.,International Journal of Computer Applications (0975 8887) Volume1 No. 12,2010.

References

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