1,424 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
Fast, parallel and secure cryptography algorithm using Lorenz's attractor
A novel cryptography method based on the Lorenz's attractor chaotic system is
presented. The proposed algorithm is secure and fast, making it practical for
general use. We introduce the chaotic operation mode, which provides an
interaction among the password, message and a chaotic system. It ensures that
the algorithm yields a secure codification, even if the nature of the chaotic
system is known. The algorithm has been implemented in two versions: one
sequential and slow and the other, parallel and fast. Our algorithm assures the
integrity of the ciphertext (we know if it has been altered, which is not
assured by traditional algorithms) and consequently its authenticity. Numerical
experiments are presented, discussed and show the behavior of the method in
terms of security and performance. The fast version of the algorithm has a
performance comparable to AES, a popular cryptography program used commercially
nowadays, but it is more secure, which makes it immediately suitable for
general purpose cryptography applications. An internet page has been set up,
which enables the readers to test the algorithm and also to try to break into
the cipher in
Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption
Optical chaos is a topic of current research characterized by
high-dimensional nonlinearity which is attributed to the delay-induced
dynamics, high bandwidth and easy modular implementation of optical feedback.
In light of these facts, which adds enough confusion and diffusion properties
for secure communications, we explore the synchronization phenomena in
spatiotemporal semiconductor laser systems. The novel system is used in a
two-phase colored image encryption process. The high-dimensional chaotic
attractor generated by the system produces a completely randomized chaotic time
series, which is ideal in the secure encoding of messages. The scheme thus
illustrated is a two-phase encryption method, which provides sufficiently high
confusion and diffusion properties of chaotic cryptosystem employed with unique
data sets of processed chaotic sequences. In this novel method of cryptography,
the chaotic phase masks are represented as images using the chaotic sequences
as the elements of the image. The scheme drastically permutes the positions of
the picture elements. The next additional layer of security further alters the
statistical information of the original image to a great extent along the
three-color planes. The intermediate results during encryption demonstrate the
infeasibility for an unauthorized user to decipher the cipher image. Exhaustive
statistical tests conducted validate that the scheme is robust against noise
and resistant to common attacks due to the double shield of encryption and the
infinite dimensionality of the relevant system of partial differential
equations.Comment: 20 pages, 11 figures; Article in press, Optics Communications (2011
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