A New Mode of Encryption Providing a Tweakable Strong Pseudo-random Permutation

We present PEP, which is a new construction of a tweakable strong pseudo-random permuta-tion. PEP uses a hash-encrypt-hash approach which has recently been used in the constructionof HCTR. This approach is different from the encrypt-mask-encrypt approach of constructionssuch as CMC, EME and EME∗. The general hash-encrypt-hash approach was earlier used byNaor-Reingold to provide a generic construction technique for an SPRP (but not a tweakableSPRP). PEP can be seen as the development of the Naor-Reingold approach into a fully speci-fied mode of operation with a concrete security reduction for a tweakable strong pseudo-randompermutation. The security bound of HCTR which is also based on the Naor-Reingold approachis weaker than that of PEP. Compared to previous known constructions, PEP is the only con-struction of tweakable SPRP which uses a single key, is efficiently parallelizable and can handlean arbitrary number of blocks.