Proceedings Icip International Conference on Image Processing, Feb 8, 2010
Motivated by the work of Uehara et al. [1], an improved method to recover DC coefficients from AC... more Motivated by the work of Uehara et al. [1], an improved method to recover DC coefficients from AC coefficients of DCT-transformed images is investigated in this work, which finds applications in cryptanalysis of selective multimedia encryption. The proposed under/over-flow rate minimization (FRM) method employs an optimization process to get a statistically more accurate estimation of unknown DC coefficients, thus achieving a better recovery performance. It was shown by experimental results based on 200 test images that the proposed DC recovery method significantly improves the quality of most recovered images in terms of the PSNR values and several state-of-the-art objective image quality assessment (IQA) metrics such as SSIM and MS-SSIM.
Unimodal maps have been broadly used as a base of new encryption strategies. Recently, a stream c... more Unimodal maps have been broadly used as a base of new encryption strategies. Recently, a stream cipher has been proposed in the literature, whose keystream is basically a symbolic sequence of the (one-parameter) logistic map or of the tent map. In the present work a thorough analysis of the keystream is made which reveals the existence of some serious security problems.
In ISNN'04, a novel symmetric cipher was proposed, by combining a chaotic signal and a clipped ne... more In ISNN'04, a novel symmetric cipher was proposed, by combining a chaotic signal and a clipped neural network (CNN) for encryption. The present paper analyzes the security of this chaotic cipher against chosen-plaintext attacks, and points out that this cipher can be broken by a chosen-plaintext attack. Experimental analyses are given to support the feasibility of the proposed attack.
Recently, an image encryption scheme based on chaotic standard and logistic maps was proposed. Th... more Recently, an image encryption scheme based on chaotic standard and logistic maps was proposed. This paper studies the security of the scheme and shows that it can be broken with only one chosen-plaintext. Some other security defects of the scheme are also reported.
Recently, an image encryption scheme based on a compound chaotic sequence was proposed. In this p... more Recently, an image encryption scheme based on a compound chaotic sequence was proposed. In this paper, the security of the scheme is studied and the following problems are found: (1) a differential chosen-plaintext attack can break the scheme with only three chosen plain-images; (2) there is a number of weak keys and some equivalent keys for encryption; (3) the scheme is not sensitive to the changes of plain-images; and (4) the compound chaotic sequence does not work as a good random number resource.
This paper studies the security of a recently-proposed MPEG-video encryption scheme based on secr... more This paper studies the security of a recently-proposed MPEG-video encryption scheme based on secret Huffman tables. Our cryptanalysis shows that: 1) the key space of the encryption scheme is not sufficiently large against divide-and-conquer (DAC) attack and known-plaintext attack; 2) it is possible to decrypt a cipher-video with a partially-known key, thus dramatically reducing the complexity of the DAC brute-force attack in some cases; 3) its security against the chosen-plaintext attack is very weak. Some experimental results are included to support the cryptanalytic results with a brief discuss on how to improve this MPEG-video encryption scheme.
At ISCAS'2005, Yen et al. presented a new chaos-based cryptosystem for multimedia transmission na... more At ISCAS'2005, Yen et al. presented a new chaos-based cryptosystem for multimedia transmission named "Multimedia Cryptography System" (MCS). No cryptanalytic results have been reported so far. This paper presents a differential attack to break MCS, which requires only seven chosen plaintexts. The complexity of the attack is O(N), where $N$ is the size of plaintext. Experimental results are also given to show the real performance of the proposed attack.
Chaotic systems have been broadly exploited through the last two decades to build encryption meth... more Chaotic systems have been broadly exploited through the last two decades to build encryption methods. Recently, two new image encryption schemes have been pro- posed, where the encryption process involves a permutation operation and an XOR- like transformation of the shuffled pixels, which are controlled by three chaotic sys- tems. This paper discusses some defects of the schemes and how
Proceedings Icip International Conference on Image Processing, Feb 8, 2010
Motivated by the work of Uehara et al. [1], an improved method to recover DC coefficients from AC... more Motivated by the work of Uehara et al. [1], an improved method to recover DC coefficients from AC coefficients of DCT-transformed images is investigated in this work, which finds applications in cryptanalysis of selective multimedia encryption. The proposed under/over-flow rate minimization (FRM) method employs an optimization process to get a statistically more accurate estimation of unknown DC coefficients, thus achieving a better recovery performance. It was shown by experimental results based on 200 test images that the proposed DC recovery method significantly improves the quality of most recovered images in terms of the PSNR values and several state-of-the-art objective image quality assessment (IQA) metrics such as SSIM and MS-SSIM.
Unimodal maps have been broadly used as a base of new encryption strategies. Recently, a stream c... more Unimodal maps have been broadly used as a base of new encryption strategies. Recently, a stream cipher has been proposed in the literature, whose keystream is basically a symbolic sequence of the (one-parameter) logistic map or of the tent map. In the present work a thorough analysis of the keystream is made which reveals the existence of some serious security problems.
In ISNN'04, a novel symmetric cipher was proposed, by combining a chaotic signal and a clipped ne... more In ISNN'04, a novel symmetric cipher was proposed, by combining a chaotic signal and a clipped neural network (CNN) for encryption. The present paper analyzes the security of this chaotic cipher against chosen-plaintext attacks, and points out that this cipher can be broken by a chosen-plaintext attack. Experimental analyses are given to support the feasibility of the proposed attack.
Recently, an image encryption scheme based on chaotic standard and logistic maps was proposed. Th... more Recently, an image encryption scheme based on chaotic standard and logistic maps was proposed. This paper studies the security of the scheme and shows that it can be broken with only one chosen-plaintext. Some other security defects of the scheme are also reported.
Recently, an image encryption scheme based on a compound chaotic sequence was proposed. In this p... more Recently, an image encryption scheme based on a compound chaotic sequence was proposed. In this paper, the security of the scheme is studied and the following problems are found: (1) a differential chosen-plaintext attack can break the scheme with only three chosen plain-images; (2) there is a number of weak keys and some equivalent keys for encryption; (3) the scheme is not sensitive to the changes of plain-images; and (4) the compound chaotic sequence does not work as a good random number resource.
This paper studies the security of a recently-proposed MPEG-video encryption scheme based on secr... more This paper studies the security of a recently-proposed MPEG-video encryption scheme based on secret Huffman tables. Our cryptanalysis shows that: 1) the key space of the encryption scheme is not sufficiently large against divide-and-conquer (DAC) attack and known-plaintext attack; 2) it is possible to decrypt a cipher-video with a partially-known key, thus dramatically reducing the complexity of the DAC brute-force attack in some cases; 3) its security against the chosen-plaintext attack is very weak. Some experimental results are included to support the cryptanalytic results with a brief discuss on how to improve this MPEG-video encryption scheme.
At ISCAS'2005, Yen et al. presented a new chaos-based cryptosystem for multimedia transmission na... more At ISCAS'2005, Yen et al. presented a new chaos-based cryptosystem for multimedia transmission named "Multimedia Cryptography System" (MCS). No cryptanalytic results have been reported so far. This paper presents a differential attack to break MCS, which requires only seven chosen plaintexts. The complexity of the attack is O(N), where $N$ is the size of plaintext. Experimental results are also given to show the real performance of the proposed attack.
Chaotic systems have been broadly exploited through the last two decades to build encryption meth... more Chaotic systems have been broadly exploited through the last two decades to build encryption methods. Recently, two new image encryption schemes have been pro- posed, where the encryption process involves a permutation operation and an XOR- like transformation of the shuffled pixels, which are controlled by three chaotic sys- tems. This paper discusses some defects of the schemes and how
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