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Alomair proposed a new authenticated encryption scheme OKH at ACNS 2012, and proved the security, i.e. authenticity and privacy , of OKH. Our research shows that it is not the case. We only need one query to break the authenticity of OKH with success probability of 1, and two queries to break the privacy of OKH with success probability of 1 − 1/2 n , where(More)
Among various cryptographic schemes, CBC-based MACs belong to the few ones most widely used in practice. Such MACs iterate a blockcipher EK in the so called Cipher-Block-Chaining way, i.e. Ci = EK (Mi ⊕ Ci−1) , offering high efficiency in practical applications. In the paper, we propose a new deterministic variant of CBC-based MACs that is provably secure(More)
Almost all current block-cipher-based MACs reduce their security to the pseudorandomness of their underlying block ciphers, except for a few of them to the unpredictability, a strictly weaker security notion than pseudorandomness. However, the latter MACs offer relatively low efficiency. In this paper, we investigate the feasibility of constructing rate-1(More)