## Cryptology ePrint Archive: Report 2001/012

Ciphers with Arbitrary Finite Domains

John Black and Phillip Rogaway

Abstract: We introduce the problem of enciphering members of a finite set $M$ where $k=|M|$ is arbitrary (in particular, it need not be a power of two). We want to achieve this goal starting from a block cipher (which requires a message space of size $N=2^n$, for some $n$). We look at a few solutions to this problem, focusing on the case when $M=[0, k-1]$.

Category / Keywords: Ciphers, Modes of Operation, Provable security, Symmetric Encryption