Unconditionally Secure Blind Signatures

Unconditionally secure signature schemes revisited

“…In the typical VEA setup of current literature [7,10,12], the arbiter is assumed to be a glorified verifier, with the same type of keying information as an arbitrary verifier. The arbiter is assumed to follow the rules of the dispute resolution method honestly and is otherwise treated as a normal verifier in the context of the security model, i.e., he is allowed to be dishonest otherwise.…”

“…The Hara et al [7] model for unconditionally secure blind signatures is essentially the same as the Shikata et al model with an added blindness condition. Hara et al separate the unforgeability definition of [12] into a weaker notion of unforgeability and an additional non-repudiation requirement.…”

“…The non-repudiation requirement actually treats more cases than a simple nonrepudiation attack (as the success of the attack is not dependent on dispute resolution), so the reason for this separation is unclear. The authors of [7] also allow the signer to be the target verifier, which was not explicitly allowed in the Shikata et al model, and so add a separate unforgeability definition for this case.…”

“…That is, it is important to distinguish between signatures that are created using a user's signing algorithm and signatures that may satisfy one or more user verification algorithms. Current research [5,6,10,12,7] has proposed various models for unconditionally secure signature schemes, but these models do not fully treat the implications of having multiple verification algorithms or analyze the need for (and trust questions associated with) having a dispute resolution mechanism. We address both of these issues in this paper.…”

“…Shikata et al [12] introduced a model using notions from public-key cryptography, which was also adopted in the work by Hara et al [7] on blind signatures. Safavi-Naini et al [10] presented a MAC-based model meant to encompass the notions developed by Shikata et al In this work, we present a new security model.…”