Sha-zam: A Block Cipher. Fast as DES, Secure as SHA

We describe a block cipher which is both practical and provably secure as SHA-1. The cipher uses the Secure Hash Algorithm (SHA-1) as an underlying primitive, and we show that any succesful attack on the cipher results in a succesful attack against one or more of the hallowed properties of SHA-1. Moreover, our block cipher is still as fast as the Data Encryption Standard (DES). We also describe a practical Pseudo-Random Generator which again is as secure as SHA-1. We apply this generator for secure key scheduling and since it is based on the same underlying primitive as our cipher, we get eecient reuse of our code. Finally we describe a construction of an eecient family of universal hash functions which are used by our cipher, which may be of independent interest.

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