100 research outputs found
Chosen-plaintext attack of an image encryption scheme based on modified permutation-diffusion structure
Since the first appearance in Fridrich's design, the usage of
permutation-diffusion structure for designing digital image cryptosystem has
been receiving increasing research attention in the field of chaos-based
cryptography. Recently, a novel chaotic Image Cipher using one round Modified
Permutation-Diffusion pattern (ICMPD) was proposed. Unlike traditional
permutation-diffusion structure, the permutation is operated on bit level
instead of pixel level and the diffusion is operated on masked pixels, which
are obtained by carrying out the classical affine cipher, instead of plain
pixels in ICMPD. Following a \textit{divide-and-conquer strategy}, this paper
reports that ICMPD can be compromised by a chosen-plaintext attack efficiently
and the involved data complexity is linear to the size of the plain-image.
Moreover, the relationship between the cryptographic kernel at the diffusion
stage of ICMPD and modulo addition then XORing is explored thoroughly
A chaotic image encryption scheme owning temp-value feedback
This paper presents a novel efficient chaotic image encryption scheme, in
which the temp-value feedback mechanism is introduced to the permutation and
diffusion procedures. Firstly, a simple trick is played to map the plain-image
pixels to the initial condition of the Logistic map. Then, a pseudorandom
number sequence (PRNS) is obtained from iterating the map. The permutation
procedure is carried out by a permutation sequence which is generated by
comparing the PRNS and its sorted version. The diffusion procedure is composed
of two reversely executed rounds. During each round, the current plain-image
pixel and the last cipher-image pixel are used to produce the current
cipher-image pixel with the help of the Logistic map and a pseudorandom number
generated by the Chen system. To enhance the efficiency, only expanded XOR
operation and modulo 256 addition are employed during diffusion. Experimental
results show that the new scheme owns a large key space and can resist the
differential attack. It is also efficient.Comment: 10 pages, 4 figure
Breaking an image encryption algorithm based on chaos
Recently, a chaos-based image encryption algorithm called MCKBA (Modified
Chaotic-Key Based Algorithm) was proposed. This paper analyzes the security of
MCKBA and finds that it can be broken with a differential attack, which
requires only four chosen plain-images. Performance of the attack is verified
by experimental results. In addition, some defects of MCKBA, including
insensitivity with respect to changes of plain-image/secret key, are reported.Comment: 10 pages, 4 figure
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