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Paper: Cryptanalysis of Ring Signature and Ring Signcryption Schemes

Authors:
S. Sree Vivek
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URL: http://eprint.iacr.org/2009/052
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Abstract: Ring signature and ring signcryption are cryptographic primitives, that allow an user to sign and signcrypt a message respectively without revealing their identity, i.e. the verifier or the unsigncrypter is convinced that the message is valid and authentic but is handicapped of knowing the identity of the actual signer or signcrypter. In this paper we consider three schemes, the first one is a ring signature scheme and the second one is a ring signcryption scheme, we demonstrate attacks on them to show that, both schemes lack anonymity and the latter doesn't provide confidentiality. We also consider a secret authenticatable anonymous signcryption scheme with identity privacy as the third scheme in our paper, which is a ring signcryption scheme that allows the actual signcrypter to reveal his identity (if required in a dispute at a later point of time). We show that this scheme is void of indistinguishability because the ciphertext is distinguishable during the challenge phase of the confidentiality game.
BibTeX
@misc{eprint-2009-18255,
  title={Cryptanalysis of Ring Signature and Ring Signcryption Schemes},
  booktitle={IACR Eprint archive},
  keywords={Ring Signature, Ring Signcryption, Anonymity, Indistinguishability, Confidentiality, Cryptanalysis, Bilinear Pairing},
  url={http://eprint.iacr.org/2009/052},
  note={ ssreevivek@gmail.com 14298 received 2 Feb 2009, last revised 22 Feb 2009},
  author={S. Sree Vivek},
  year=2009
}