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Modular Multiplication for FPGA Implementation of the IDEA Block Cipher

Jean-Luc Beuchat 1
1 ARENAIRE - Computer arithmetic
Inria Grenoble - Rhône-Alpes, LIP - Laboratoire de l'Informatique du Parallélisme
Abstract : The IDEA block cipher is a symmetric-key algorithm which encrypts 64-bit plaintext blocks to 64-bit ciphertext blocks, using a 128-bit secret key. The security of IDEA relies on combining operations from three algebraic groups: integer addition modulo 2^n, bitwise exclusive or of two n-bit words, and integer multiplication modulo (2^n+1) which is the critical arithmetic operation of the block cipher. In this paper, we investigate three algorithms based on a small multiplication with a subsequent modulo correction. They are particularly well suited for the latest FPGA devices embedding small multiplier blocks, like the Virtex-II family. We also consider a multiplier based on modulo (2^n+1) adders. Several architectures of the IDEA block cipher are then described and compared from different point of view: throughput to area ratio or adequation with feedback and non-feedback chaining modes. Our fastest circuit achieves a throughput of 8.5 Gb/s, which is, to our knowledge, the best rate reported in the literature.
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Contributor : Rapport de Recherche Inria <>
Submitted on : Tuesday, May 23, 2006 - 7:36:24 PM
Last modification on : Wednesday, November 20, 2019 - 3:21:04 AM
Long-term archiving on: : Sunday, April 4, 2010 - 10:49:44 PM


  • HAL Id : inria-00072030, version 1



Jean-Luc Beuchat. Modular Multiplication for FPGA Implementation of the IDEA Block Cipher. RR-4558, INRIA. 2002. ⟨inria-00072030⟩



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