Random Oracle Combiners: Breaking the Concatenation Barrier for Collision-Resistance

ePrint Report: Random Oracle Combiners: Breaking the Concatenation Barrier for Collision-Resistance

Yevgeniy Dodis, Niels Ferguson, Eli Goldin, Peter Hall, Krzysztof Pietrzak

Suppose two parties have hash functions $h_1$ and $h_2$ respectively, but each only trusts the security of their own. We wish to build a hash combiner $C^{h_1, h_2}$ which is secure so long as either one of the underlying hash functions is. This question has been well-studied in the regime of collision resistance. In this case, concatenating the two …

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