Chaos-based fast colour image encryption scheme with true random number keys from environmental noise

ABSTRACT:

The paper proposes a chaos-based colour image encryption scheme, the highlight is that the randomly sampled noise signal is applied to serve as the initial values of a chaotic system. The 256-bit hash value of noise is transformed into the one-time initial values of the Liu system. The sequences generated by Liu system are subjected to three batteries of TestU01. Exclusive OR, the only operation, is applied to diffuse the pixels, and some measures are taken to speed up the encryption process. Finally, some statistical tests are performed to assess reliability and efficiency of the proposed cryptosystem in terms of time complexity and security.

PROJECT OUTPUT VIDEO:

EXISTING SYSTEM & DISADVANTAGES:

• According to Shannon’s theory of secure communication, only the cryptosystem based on one-time key is theoretically unbreakable, but in practical applications, there exist some problems.

• For example, one-time keys require that the key stream should be generated by true random number generator (TRNG) and never be re-used, the key stream and the plain message must have the same length. Even if the key stream is generated by TRNG, it is impractical to send the whole key stream to the receiver.

PROPOSED SYSTEM:

• In this paper, we design a color image encryption scheme which uses one-time keys from environmental noise. The hash value of true random environmental noise is applied to generate the initial conditions of the chaotic system.

• The Liu system is employed to generate three sequences with good randomness to encrypt three color components with XOR operation. Some effective measures have been taken to speed up the encryption process.

• The experimental results demonstrate the effectiveness of the proposed scheme.

ADVANTAGES OF PROPOSED SYSTEM:

• The running speed is effectively improved by some time-saving operations, such as effectively determine iterative times according to image size, faster integer operations, exactly amplification factor of state variables, matrix calculation and pre-allocated memory.

MODULES:

1. Key Generation Process

2. Color Image Encryption

3. Color Image Decryption

MODULE DESCRIPTION:

1. Key Generation Process:

We proposed color image encryption and decryption based on chaos method. Chaos method generate the key for both encryption and decryption process.

Key Generation steps:

• The proposed cryptosystem utilizes a 256-bit external key H, which is the common hash value calculated by SHA-256 and random noise signal was generated. Noise signal has floating values.

• First, the initial values of xo, yo and zo, control parameter c, and pre-iteration times no can be derived as follows:

• Second, initial three floating-point number sequences are generated based on initial values, control parameters and step length.

• Finally again three floating-point number sequences are generated from initial sequence and signal gain value. These three sequences are called as key.

2. Color Image Encryption:

Step 1: Get the hash value of H and noise signal N, and then calculate the initial values of x0, y0 and z0, the control parameter c and n0.

Step 2: Generate the three floating-point number sequences of X, Y and Z with the same length of plain image.

X = {x1, x2, …, xL}

Y = {y1, y2, …, yL}

Z = {z1, z2, …, zL}

Step 3: Then generate three sequences of XR, XG, and XB.

xRi = αxi

yGi = αyi

zBi = αzi

where xRi ∈ XR, yGi ∈ YG and zBi ∈ ZB, i = 1, 2, …, L, α is signal gain.

Step 4: Apply XR, XG and XB to encrypt the red, green and blue components of plain image (P) to get CR, CG and CB, and then combine them into the ciphered image C.

cRi = pRi ⊕ (xRi mod 256)

cGi = pGi ⊕ (yGi mod 256)

cBi = pBi ⊕ (zBi mod 256)

where the symbol ⊕ denotes a bitwise XOR operation.

3. Color Image Decryption:

Step 1: Same as Step 2 and step 3of the encryption algorithm above; the aim is to get three floating-point number sequences of XR, XG and XB.

Step 2: Apply XR, XG and XB to decrypt the red, green and blue components of image C, to get PR, PG and PB, and then combine them into the deciphered image P.

pRi = cRi ⊕ (xRi mod 256)

pGi = cGi ⊕ (yGi mod 256)

pBi = cBi ⊕ (zBi mod 256)

where the symbol ⊕ denotes a bitwise XOR operation.

SYSTEM REQUIREMENTS:

HARDWARE REQUIREMENTS:

• System           : Pentium Dual Core.

• Hard Disk      : 120 GB.

• Monitor          : 15’’ LED

• Input Devices : Keyboard, Mouse

• Ram                : 1GB.

SOFTWARE REQUIREMENTS:

• Operating system : Windows 7.

• Coding Language : MATLAB

• Tool                      : MATLAB R2013A

REFERENCE:

Hongjun Liu1,2 , Abdurahman Kadir3, Xiaobo Sun4, “Chaos-based fast colour image encryption scheme with true random number keys from environmental noise”, IEEE IET Image Processing, 2017.