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Proxy signature allows an original signer to delegate his signing capacity to a proxy signer. Then the proxy signer creates a signature on behalf of the original singer. When a receiver verifies proxy signature, he verifies the signature itself and original signer's delegation together. In this paper, the present existent problem of proxy revocation is analyzed. Two drawbacks of the Wang's proxy signature scheme based on elliptic curve are given. Then an improved scheme is presented. On the base of this improved scheme, a secure proxy blind signature scheme based on elliptic curve with proxy revocation is proposed by applying Abe-Okamoto partially blind signature. By embedding non-blind time-stamp in the signatures, the original signer can revoke delegation whenever necessary and all valid proxy signatures generated earlier can longer be verified. Besides having the basic properties of the proxy signature, the proposed schemes solve proxy revocation without trustee, and prevent public key substitution attack, original signer's forgery as well as proxy misuse.
Date of Conference: July 30 2007-Aug. 1 2007