Block Ciphers – Focus On The Linear Layer (feat. PRIDE)

Martin R. Albrecht, Benedikt Driessen, Elif Bilge Kavun, Gregor Leander, Chris­tof Paar, Tolga Yalcin

In Proceedings of the 34th International Cryptology Conference 2014 (CRYPTO’14), volume 8616 of Lecture Notes in Computer Science, pages 57-76. Springer, Santa Barbara, CA, US, August 17-21, 2014


The linear layer is a core component in any substitution-permutation network block cipher. Its design significantly influences both the security and the efficiency of the resulting block cipher. Surprisingly, not many general constructions are known that allow to choose trade-offs between security and efficiency. Especially, when compared to Sboxes, it seems that the linear layer is crucially understudied. In this paper, we propose a general methodology to construct good, sometimes optimal, linear layers allowing for a large variety of trade-offs. We give several instances of our construction and on top underline its value by presenting a new block cipher. PRIDE is optimized for 8-bit micro-controllers and significantly outperforms all academic solutions both in terms of code size and cycle count.


Tags: block cipher, embedded processors, linear layer, wide-trail