The SPEED cipher

Abstract

SPEED is a private key block cipher. It supports three variable parameters: (1) data length — the length of a plaintext/ciphertext of SPEED can be 64, 128 or 256 bits. (2) key length — the length of an encryption/decryption key of SPEED can be any integer between 48 and 256 (inclusive) and divisible by 16. (3) rounds — the number of rounds involved in encryption/decryption can be any integer divisible by 4 but not smaller than 32. SPEED is compact, which is indicated by the fact that the object code of a straightforward implementation of SPEED in the programming language C occupies less than 3 kilo-bytes. It makes full use of current, and more importantly, emerging CPU architectures which host a large number of high-speed hardware registers directly available to application programs. Another important feature of SPEED is that it is built on recent research results on highly nonlinear cryptographic functions, as well as other counter-measures against differential and linear cryptanalytic attacks. It is hoped that the compactness, high throughput and adjustable parameters offered by SPEED, together with the fact that the cipher is in the public domain, would make it an attractive alternative cipher for security applications including electronic financial transactions.