Security Analysis of Shim\u27s Authenticated Key Agreement Protocols from Pairings

Recently, Shim proposed a tripartite authenticated key agreement protocol from Weil pairing to overcome the security flaw in Joux\u27s protocol. Later, Shim also proposed an ID-based authenticated key agreement protocol which is an improvement of Smart\u27s protocol in order to provide the forward secrecy. In this paper, we show that these two protocols are insecure against the key-compromise impersonation attack and the man-in-the-middle attack respectively

On the Security of Some Proxy Signature Schemes

Digital signature scheme is an important research topic in cryptography

Security Analysis of Shim’s Authenticated Key Agreement Protocols from Pairings. Cryptology ePrint Archive, Report 2003/113

Recently, Shim proposed a tripartite authenticated key agreement protocol from Weil pairing to overcome the security flaw in Joux’s protocol. Later, Shim also proposed an ID-based authenticated key agreement protocol which is an improvement of Smart’s protocol in order to provide the forward secrecy. In this paper, we show that these two protocols are insecure against the key-compromise impersonation attack and the manin-the-middle attack respectively

Cryptanalysis of A Strong Proxy Signature Scheme with Proxy Signer Privacy Protection

ABSTRACT rant as a part information of verification. Furthermore, in terms of proxy delegation steps, some proxy signature schemes are non-interactive [46] and some schemes [7] Recently, Shum and Wei proposed an enhancement are interactive. No matter what kind of proxy signature to the Lee et Proxy signature such that the schemes, a proxy scheme provide good proxy signer's identity is hidden behind an alias. In security properties, this paper, we show that Shum and Wei's enhancement is insecure against the original signer's forgery. In other Lee et al. properties that a strong words, their scheme does not possess the strong unforge- proxy signature sclleme should provide: ability security requirement. Strong Unforgeability: Only the legitimate proxy Keywords: Cryptanalysis, Proxy Signature, Signa- signer can generate a-lid proxy eve

On the security of some proxy signature schemes

Digital signature scheme is an important research topic in cryptography. An ordinary digital signature scheme allows a signer to create signatures of documents and the generated signatures can be verified by any person. A proxy signature scheme, a variation of ordinary digital signature scheme, enables a proxy signer to sign messages on behalf of the original signer. To be used in different applications, many proxy signatures were proposed. In this paper, we review Lee et al.’s strong proxy signature scheme, multi-proxy signature scheme, and its application to a secure mobile agent, Shum and Wei’s privacy protected strong proxy signature scheme, and Park and Lee’s nominative proxy signature scheme, and show that all these proxy signature schemes are insecure against the original signer’s forgery. In other words, these schemes do not possess the unforgeability property which is a desired security requirement for a proxy signature scheme