Image Security

Presented By:Satyendra RajputPh.D scholar

Outline• Introduction• Method of Encryption Techniques• Classification of Attack• Objective• Image Encryption• Basic Method for Image Encryption• Literature Review• Conclusion

BASIC MODEL FOR SECURITY

Cont...

USES OF ENCRYPTION• Protect information on your computer.• Protect information in transit• Confidentiality of medical, personal and transaction

records• Email program• Digital signature

Security

Cont...

Classical encryption techniques

• As opposed to modern cryptography• Goals: – To introduce basic concepts & terminology of

encryption– To prepare us for studying modern cryptography

Basic terminology• Plaintext: original message to be encrypted

• Ciphertext: the encrypted message

• Enciphering or encryption: the process of converting plaintext into ciphertext

• Encryption algorithm: performs encryption

– Two inputs: a plaintext and a secret key

8

Symmetric Cipher Model

9

Cont...• Deciphering or decryption: recovering plaintext from

ciphertext

• Decryption algorithm: performs decryption– Two inputs: ciphertext and secret key

• Secret key: same key used for encryption and decryption– Also referred to as a symmetric key

Cont...• Cipher or cryptographic system : a scheme for

encryption and decryption

• Cryptography: science of studying ciphers

• Cryptanalysis: science of studying attacks against cryptographic systems

• Cryptology: cryptography + cryptanalysis

Ciphers• Symmetric cipher: same key used for encryption and

decryption

– Block cipher: encrypts a block of plaintext at a time

(typically 64 or 128 bits)

– Stream cipher: encrypts data one bit or one byte at a

time

• Asymmetric cipher: different keys used for encryption and decryption

12

Symmetric Encryption• Conventional / secret-key / single-key• Sender and recipient share a common key• All classical encryption algorithms are symmetric

13

Symmetric Encryption• Mathematically:

Y = EK(X) or Y = E(K, X) X = DK(Y) or X = D(K, Y)

• X = plaintext• Y = ciphertext• K = secret key• E = encryption algorithm• D = decryption algorithm• Both E and D are known to public

14

Classical Ciphers

• Plaintext is viewed as a sequence of elements (e.g., bits or characters)

• Substitution cipher: replacing each element of the plaintext with another element.

• Transposition (or permutation) cipher: rearranging the order of the elements of the plaintext.

• Product cipher: using multiple stages of substitutions and transpositions

15

Caesar Cipher• Earliest known substitution cipher• Invented by Julius Caesar • Each letter is replaced by the letter three positions

further down the alphabet.• Plain: a b c d e f g h i j k l m n o p q r s t u v w x y z Cipher: D E F G H I J K L M N O P Q R S T U V W X Y Z A B C

• Example: ohio state RKLR VWDWH

16

Caesar Cipher

• Mathematically, map letters to numbers:a, b, c, ..., x, y, z0, 1, 2, ..., 23, 24, 25

• Then the general Caesar cipher is:c = EK(p) = (p + k) mod 26

p = DK(c) = (c – k) mod 26

• Can be generalized with any alphabet.

17

Objective

• The main Objective was to provide a Image encryption mechanism which provides high security level, less computational time and power in reliable and efficient way to deal with balky, real time data.

• And Reduced the key size with equivalent efficient of large key size.

Real life examples• Online Banking• E-commerce• Student Records• Health Records• ATM Machines database• Social Networking• Bussinesses

Classify Security Attacks • Passive attacks - eavesdropping on, or monitoring

of, transmissions to:– obtain message contents, or– monitor traffic flows

• Active attacks – modification of data stream to:– masquerade of one entity as some other– replay previous messages– modify messages in transit– denial of service

21Bill Figg

Types of Attacks

Cont...

WHY IMAGE ENCRYPTION ?• Nowadays, information security is becoming more important in

data storage and transmission. • Images are widely used in different-different processes.

Therefore, the security of image data from unauthorized uses is important.

• Image encryption plays a important role in the field of information hiding. 

• Image encryption method prepared information unreadable. Therefore, no hacker or eavesdropper, including server administrators and others, have access to original message or any other type of transmitted information through public networks such as internet

REQUIREMENTS OF IMAGE ENCRYPTION

• Ability to get the pixels of the original image.• Create a strong encryption image such that it cannot

be hacked easily.• Faster encryption time such that encrypted image is

transferred faster to the person.• Perfection in the original image we obtain after

decrypting it.

CHALLENGES IN IMAGE ENCRYPTION

• The two main problems that arise in image encryption process are with respect to:

• Computational time.• Security level.• Real time image encryption prefers ciphers that take

less amount of computational time without compromising security.

Existing System

• There are traditional image encryption techniques like DES, Triple-DES and IDEA.

• Limitations o long computational time o high computing power.• Not suitable for practical image encryption

and for online communications

Applicability• This encryption scheme is suitable for applications

like

Internet image encryption

secure transmission of confidential information in the Internet.

Problem with conventional Methods

• Not suitable for practical image encryption , such as on-line communication due to image features such as:

• Bulk data capacity• High correlation among pixels

• Non flexibility in performance characteristics and level of security

• They may be susceptible to linear and differential cryptanalysis

Exiting System• Owner encrypts the original image using a standard cipher

with an encryption key.• After producing the encrypted image, the content owner

hands over it to a data hider (e.g., a database manager) and the data hider can embed some auxiliary data into the encrypted image by losslessly vacating some room according to a data hiding key.

• Then a receiver, maybe the content owner himself or an authorized third party can extract the embedded data with the data hiding key and further recover the original image from the encrypted version according to the encryption key

Disadvantages of Existing system

• All previous methods decrypted data by reversibly from the encrypted images, which may be subject to some errors on data extraction and/or image restoration.

• It is difficult for data encrypted to reversibly decrypt the data on an image.

Methods

• Advanced Encryption Standard• International Data Encryption Standard

(IDEA)• Blowfish• RC5

Advanced Encryption Standard• Proposed successor to DES• DES drawbacks

– algorithm designed for 1970s hardware implementation– performs sluggishly in software implementations

• 3DES is 3 times slower due to 3 rounds– 64 bit blocksize needs to be increased to speed things up

• AES Overview– 128, 192, 256 bit blocksize (128 bit likely to be most common)– process entire block in parallel– 128 bit key, expanded into 44, 32bit words with 4 words used for each

round

International Data Encryption Standard (IDEA)

• Developed in Switzerland 1991• 128 bit key, 64 bit blocksize, 8 rounds• algorithm is quite different than DES, – doesn’t use S-boxes– uses binary addition rather than exclusive-or

• used in Pretty Good Privacy (PGP)

Blowfish• 1993 – Bruce Schneier• Popular alternative to DES• Variable length keys - 128 bits but up to 448 bits• up to 16 rounds • 64 bit blocksize• used in many commercial software packages

LITERATURE SURVEY • Modified AES Based Algorithm for Image

encryption, 2007 • M. Zeghid, M. Machhout, L. Khriji, A. Baganne, and

R. Tourki• Analyze the Advanced Encryption Standard (AES), • Image encryption technique they add a key stream

generator (A5/1, W7) to AES • For ensure improving the encryption performance.

Cont...• Image Encryption Using Block-Based

Transformation Algorithm, 2008 • Mohammad Ali Bani Younes and Aman

Blowfish Encrypted image

• Block-based transformation algorithm based on the combination of image transformation and a well known encryption and decryption algorithm called Blowfish.

Q! Q2

Q3 Q4

Cont...

4 2

1 3 Blowfish image

•The original image was divided into blocks, which were rearranged into a transformed image using a transformation algorithm,• Then the transformed image was encrypted using the Blowfish algorithm

Cont...• Results showed that the correlation between image

elements was significantly decreased. • Their results also show that increasing the number of

blocks by using smaller block sizes resulted in a lower correlation and higher entropy.

Cont...• Image Encryption Using Self-Invertible Key Matrix of

Hill Cipher Algorithm, 2008 • Saroj Kumar Panigrahy, Bibhudendra Acharya and Debasish

Jena • They are generating self-invertible matrix for Hill Cipher

algorithm.• Using this key matrix they encrypted gray scale as well as

colour images.• Their algorithm works well for all types of gray scale as

well as colour images except for the images with background of same gray level or same colour.

Cont...• An Image Encryption Approach Using a

Combination of Permutation Technique Followed by Encryption, 2008

• Mohammad Ali Bani Younes and Aman Jantan • Introduce a new permutation technique based on the

combination of image permutation and a well known encryption algorithm called RijnDael.

• The original image was divided into 4 pixels × 4 pixels blocks

Cont...• Which were rearranged into a permuted image using

a permutation process• Then the generated image was encrypted using the

RijnDael algorithm. • Their results showed that the correlation between

image elements was significantly decreased by using the combination technique and higher entropy was achieved

Cont...• Image Encryption Using Advanced Hill Cipher

Algorithm, 2009 • Bibhudendra Acharya, Saroj Kumar Panigrahy, Sarat

Kumar Patra, and Ganapati Panda• Proposed an advanced Hill (AdvHill) cipher algorithm • which uses an Involutory key matrix for encryption. • They have taken different images and encrypted them

using original Hill cipher algorithm and their proposed AdvHill cipher algorithm

Cont...

• And it is clearly noticeable that original Hill Cipher can’t encrypt the images properly

• If the image consists of large area covered with same colour or gray level.

• But their proposed algorithm works for any images with different gray scale as well as colour images.

Cont...• Digital image encryption algorithm based on

chaos and improved DES, 2009• Zhang Yun-peng, Liu Wei, Cao Shui-ping, Zhai

Zheng-jun, Nie Xuan and Dai Wei-di• In their technique firstly, new encryption scheme uses

the logistic chaos sequencer to make the pseudo-random sequence, carries on the RGB

• This sequence to the image chaotically, then makes double time encryptions with improvement DES.

• Their result show high starting value sensitivity, and high security and the encryption speed.

Cont...• Then makes double time encryptions with

improvement DES.• Their result show high starting value sensitivity, and

high security and the encryption speed.

Cont...• A Novel Image Encryption Algorithm Based on

Hash Function, 2010• Seyed Mohammad Seyedzade, Reza Ebrahimi Atani

and Sattar Mirzakuchaki• Proposed a novel algorithm for image encryption

based on SHA-512 hash function. • The algorithm consists of two main sections:

Cont...• The first does preprocessing operation to shuffle one

half of image. • The second uses hash function to generate a random

number mask. • The mask is then XORed with the other part of the

image which is going to be encrypted.

Cont...• Digital Image Encryption Algorithm Based

Composition of Two Chaotic Logistic Maps, 2010• Ismail Amr Ismail, Mohammed Amin, and Hossam Diab• Introduces an efficient chaos-based stream cipher,

composing two chaotic logistic maps and a large enough external secret key for image encryption.

• In the proposed image encryption scheme, an external secret key of 104 bit and two chaotic logistic maps are employed to confuse the relationship between the cipher image and the plain image.

Cont...• Make the cipher more robust against any attack, the

secret key is modified after encrypting of each pixel of the plain image.

• The robustness of the proposed system is further reinforced by a feedback mechanism,

• Which makes the encryption of each plain pixel depends on the key, the value of the previous cipher pixel and the output of the logistic map (data dependent property).

Cont...• New modified version of Advance Encryption

Standard based algorithm for image encryption, 2010

• Kamali S.H., Shakerian R.,Hedayati M. and Rahmani M

• Analysis Advance Encryption Standard(AES) algorithm and present a modification to the Advanced Encryption Standard (MAES) to reflect a high level security and better image encryption..

Cont...• Their result so that after modification image security

is high. • They also compare their algorithm with original AES

encryption algorithm

Cont...• Permutation based Image Encryption Technique,

2011• Sesha Pallavi Indrakanti and P.S.Avadhani• Proposes a new image encryption algorithm based on

random pixel permutation with the motivation to maintain the quality of the image.

Cont...• The technique involves three different phases in the

encryption process.• The first phase is the image encryption. • The second phase is the key generation phase.• The third phase is the identification process. This

provide confidentiality to color image with less computations Permutation process is much quick and effective.

• The key generation process is unique and is a different process

Cont...

• Image Security via Genetic Algorithm, 2011• Rasul Enayatifar and Abdul Hanan Abdullah• Proposed a new method based on a hybrid model

composed of a genetic algorithm and a chaotic function for image encryption.

• In their technique, first a number of encrypted images are constructed using the original image with the help of the chaotic function.

Cont...• In the next stage, these encrypted images are

employed as the initial population for starting the operation of the genetic algorithm.

• Then, the genetic algorithm is used to optimize the encrypted images as much as possible.

• In the end, the best cipher-image is chosen as the final encryption image.

CONCLUSION • In the digital world nowadays, the security of digital

images become more and more important• Since the communications of digital products over

open network occur more and more frequently. • In this presentation, we have surveyed existing work

on image encryption. We also give general guide line about cryptography.

CONCLUSION • We conclude that all techniques are useful for real-

time image encryption. • Techniques describes in this research that can provide

security functions and an overall visual check, which might be suitable in some applications.

• So no one can access image which transferring on open network.

CONCLUSION • In general, a well-studied, fast and secure

conventional cryptosystem should be chosen, surely those algorithms, which provides higher security

References• [1] S.S.Maniccam, N.G. Bourbakis, "Lossless image compression and

encryption using SCAN", Pattern Recognition 34 (2001),1229- 1245. • [2] William stallings, ―Cryptography and Network Security: Principles &

Practices‖, second edition. • [3]M. Zeghid, M. Machhout, L. Khriji, A. Baganne,R. Tourki, ―A

Modified AES Based Algorithm for Image Encryption‖, World Academy of Science, Engineering and Technology 27 2007.

• [4] Mohammad Ali Bani Younes and Aman Jantan ―Image Encryption Using Block-Based Transformation Algorithm‖ IAENG International Journal of Computer Science, 35,2008.

References• [5] Saroj Kumar Panigrahy, Bibhudendra Acharya and Debasish

Jen‖, Image Encryption Using Self-Invertible Key Matrix of Hill Cipher Algorithm‖1st t International Conference on Advances in Computing, Chikhli, India, 21-22 February 2008

• [6] Mohammad Ali Bani Younes and Aman Jantan, ―An Image Encryption Approach Using a Combination of Permutation Technique Followed by Encryption‖, IJCSNS International Journal of Computer Science and Network Security, VOL.8 , April 2008.

• [7]Bibhudendra Acharya, Saroj Kumar Panigrahy, Sarat Kumar Patra, and Ganapati Panda,‖ Image Encryption Using Advanced Hill Cipher Algorithm‖, International Journal of Recent Trends in Engineering, Vol. 1, No. 1, May 2009.

References• [8] Zhang Yun-peng, Liu Wei, Cao Shui-ping, Zhai Zheng-jun, Nie

Xuan , Dai Wei-di,‖ Digital image encryption algorithm based on chaos and improved DES‖, IEEE International Conference on Systems, Man and Cybernetics, 2009

• [9] Seyed Mohammad Seyedzade, Reza Ebrahimi Atani and Sattar Mirzakuchaki, ―A Novel Image Encryption Algorithm Based on Hash Function‖ 6th Iranian Conference on Machine Vision and Image Processing, 2010.