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March 22, 2007

Sony Develops "CLEFIA" - New Block Cipher Algorithm Based on State-of-the-art Design Technologies

TOKYO, March 22, 2007- Sony Corporation today announced "CLEFIA",*1 a new highly secure and efficient block cipher algorithm that delivers advanced copyright protection and authentication, which is essential in the growing environment of digital data distribution, such as music and images. Based on cutting edge cipher design techniques, Sony's "CLEFIA" block cipher maintains high security levels while providing both world-leading hardware and software implementation capabilities, the combination of which had proved difficult until now. Sony will unveil the results of this development at the "Fast Software Encryption 2007"*2international conference, to be held in Luxembourg for three days from March 26.

Sony's newly developed "Diffusion Switching Mechanism (DSM)"*3 technology is the result of research into improving security while reducing overall cost. It successfully achieves secure cipher algorithms, even with fewer operations, by selecting the optimum diffusion matrices in the Feistel structure*4. This technology enables reductions in gate size when implemented in hardware, and greater implementation efficiency when used in software.

The key advantages of "CLEFIA" are its enhanced implementation efficiency in terms of both hardware and software, and its high speed operation. When implemented in hardware it achieves maximum throughput of 1.42 Gbps using a 0.09 µm CMOS standard cell library and gate size of just 6.1K, representing the world's highest hardware gate efficiency. Consequently, "CLEFIA" is able to provide advanced capabilities, even in restrictive environments such as smart cards and mobile devices. When implemented in software it can realize high speed performance on a wide variety of processors.

The "CLEFIA" interface corresponds to 128-bit block cipher technology such as the US government's Advanced Encryption Standard (AES), and the ISO/IEC 18033-3 International Standards. Block length is 128 bits, while key length can be selected from 128 bits, 192 bits, and 256 bits.

The "CLEFIA" cipher is meticulously designed to concentrate state-of-the-art cryptanalysis techniques and achieve sufficient immunity against known cryptanalytic attacks. Sony has cooperated with Japan's leading researcher in this field to create this design, and has had the new cipher design verified by a number of third party experts overseas.

Going forward, Sony will seek to establish an environment in which "CLEFIA" can be used across various applications and products such as AV devices, while continuing to develop technologies that our customers can use with confidence.

  • *1)  Based on the French word "Clef" meaning "key".
  • *2)  International conference hosted by IACR (International Association of Cryptologic Research) for presenting research results on symmetric key cipher technology. This year is the 14th meeting.
  • *3)  Basic block cipher structure, as adopted by DES (Data Encryption Standard) etc.
  • *4)  Diffusion Switching Mechanism. Related research results previously presented at FSE2004, ASIACRYPT2004, FSE2006 etc.
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