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Chengqing Li

  1. On the impossibility of non-static quantum bit commitment between two parties.

    Втр, 02/01/2011 - 16:01 — SomNambul
    Authors: Chengqing Li, Qin Li, Dong-Yang Long, W. H. Chan, Chun-Hui Wu
    Subjects: Cryptography and Security
    Abstract

    Recently, Choi \emph{et al}. proposed an assumption on Mayers-Lo-Chau (MLC)
    no-go theorem that the state of the entire quantum system is invariable to both
    participants before the unveiling phase. This means that the theorem is only
    applicable to static quantum bit commitment (QBC). This paper find that the
    assumption is unnecessary and the MLC no-go theorem can be applied to not only
    static QBC, but also non-static one.

  2. Breaking an image encryption algorithm based on chaos.

    Пт, 07/23/2010 - 15:01 — SomNambul
    Authors: Chengqing Li, Kwok-Tung Lo, Michael Z. Q. Chen
    Subjects: Cryptography and Security
    Abstract

    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.

  3. Breaking a modified substitution-diffusion image cipher using chaotic standard and logistic maps.

    Чт, 12/17/2009 - 16:01 — SomNambul
    Authors: Chengqing Li, Kwok-Tung Lo, Shujun Li
    Subjects: Cryptography and Security
    Abstract

    Recently, an image encryption scheme based on chaotic standard and logistic
    maps was proposed. It was reported by a research group that an equivalent
    secret key can be reconstructed with only one pair of known-plaintext.
    Afterward, the scheme was enhanced by the original authors. Unfortunately, this
    paper find that the modified version still can be broken with the same breaking
    method. In addition, some other security defects existing in both the two
    schemes are reported.

  4. Security analysis of a binary image permutation scheme based on Logistic map.

    Пт, 12/11/2009 - 16:01 — SomNambul
    Authors: Chengqing Li, Kwok-Tung Lo
    Subjects: Cryptography and Security
    Abstract

    In [\textit{Pattern Recognition Letters}, in press,
    doi:10.1016/j.patrec.2009.11.008], an image scrambling encryption algorithm of
    pixel bit based on chaos map was proposed. Considering the algorithm as a
    typical binary image scrambling/permutation algorithm exerting on plaintext of
    size $M\times (8N)$, this paper proposes a novel optimal method to break it
    with some known/chosen-plaintexts. Both spacial complexity and computational
    complexity of the attack are only $O(8\cdot n_0\cdot MN)$, $n_0$ is the number
    of known/chosen-plaintexts used.

Math-arch

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