Recently, Peyravin and Jeffries proposed a password-based practical authentication scheme using oneway collision-resistant hash functions. However, Shim and Munilla independently showed that the scheme is vulnerable to off-line guessing attacks. Hölbl, Welzer and Brumenn presented an improved password-based protocols. In the paper, we showed that the improved scheme still suffers from off-line ...

Riis [Electron. J. Combin., 14(1):R44, 2007] introduced a guessing game for graphs which is equivalent to finding protocols for network coding. In this paper we prove upper and lower bounds for the winning probability of the guessing game on undirected graphs. We find optimal bounds for perfect graphs and minimally imperfect graphs, and present a conjecture relating the exact value for all grap...

From Seo and Sweeney proposed SAKA (Simple Authenticated Key agreement Algorithm), many SAKA variants were proposed to cope with the weaknesses in SAKA. However, they still are vulnerable to off-line password guessing attack. This paper proposes a new secure authenticated key exchange protocol that can resist off-line password guessing attack. To solve the vulnerability of former protocols, key...

The Shannon cipher system is studied in the context of general sources using a notion of computational secrecy introduced by Merhav & Arikan. Bounds are derived on limiting exponents of guessing moments for general sources. The bounds are shown to be tight for iid, Markov, and unifilar sources, thus recovering some known results. A close relationship between error exponents and correct decoding...