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A New Scheme for Provable Secure Anonymous Proxy Signature in the Standard Model

Toluee, Rahim | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44822 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical-Engineering
  6. Advisor(s): Salmasizadeh, Mahmoud
  7. Abstract:
  8. In order to protect the proxy signers’ privacy, many anonymous proxy signature schemes have been proposed. As far as we know, there is no provable secure anonymous proxy signature scheme without random oracles. Because the provable security in the random oracle model has received a lot of criticism, in this thesis, the aim is proposing the first provable secure anonymous proxy signature in the standard model based on existing standard assumptions.It is shown in the standard model that, the proposal is anonymous against full key exposure and existential unforgeable with the computational Diffie Hellman (CDH) and Subgroup Hiding (SGH) assumptions in bilinear groups.To provide anonymity for proxy signatures, ring signature schemes can be used. In current ring signature schemes, there is no distinguishing about the ranks of members of the ring. We propose a ring signature scheme which considers the members’ rank values. It is shown in the standard model that, the proposal is anonymous against full key exposure attack and unforgeable with respect to insider corruption with CDH and SGH assumptions in bilinear groups.Eventually,to improve the ring signature schemes used in theanonymous proxy signatures,attribute-based ring signature schemesare reviewed. For this purpose, we first show that Wenqiang et al.’s scheme in 2009 is forgeable. The second contribution is an efficient attribute-based ring signature scheme with constant size and constant number of pairing operations. It is shown in the standard model that, the proposal is unconditionally anonymous and unforgeable in the standard model with the Static Diffie Hellman (SDH) assumption in bilinear groups.Compared with the existing attribute-based ring signature scheme with constant size, the length of the signature and the pairing operations in the proposal are decreased by 1/3 and by 1/4, respectively. Thus, the efficiency of signing and verifying is improved in the proposal
  9. Keywords:
  10. Provable Security ; Standard Model ; Proxy Signature ; Random Oracle Model ; Ring Signature ; Anonymous Proxy Signature ; Attribute Based Ring Signature ; Constant Size Signature

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