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Cryptanalysis of the Hwang-Shi proxy signature scheme. (English) Zbl 1020.94014

Summary: Recently, S. J. Hwang and C. H. Shi [A proxy signature scheme without using one-way hash functions, Proc. 2000 Int. Comput. Sympos. (ISC2000), Taiwan (2000)] proposed an efficient proxy signature scheme without using one-way hash functions. In their scheme, an original signer need not send a proxy certificate to a proxy signer through secure channels. However, there are two public key substitution methods that can be used to attack their scheme. In this article, we show that their scheme is vulnerable to the public key substitution attacks.

MSC:

94A60 Cryptography
94A62 Authentication, digital signatures and secret sharing
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