CLEFIA explained

CLEFIA
Designers:	Sony
Publish Date:	2007
Certification:	CRYPTREC (Candidate)
Key Size:	128, 192, or 256 bits
Block Size:	128 bits
Structure:	Feistel network
Rounds:	18, 22, or 26
Cryptanalysis:	An improbable differential attack requiring 2^126.83 chosen plaintexts breaks 13 rounds with a complexity of 2^126.83 encryptions for the key size of length 128 bits (Tezcan, 2010).^[1] Similar attacks apply for 14 and 15 rounds of CLEFIA for the key sizes 192 and 256 bits, respectively.

CLEFIA is a proprietary block cipher algorithm, developed by Sony.^[2] Its name is derived from the French word clef, meaning "key". The block size is 128 bits and the key size can be 128 bit, 192 bit or 256 bit. It is intended to be used in DRM systems. It is among the cryptographic techniques recommended candidate for Japanese government use by CRYPTREC revision in 2013.

Standardization

CLEFIA is included in the following standards.

• ISO/IEC 29192-2:2019, Information security - Lightweight cryptography - Part 2: Block ciphers^[3]

Further reading

• Web site: Wao Wang. Xiaoyun Wang . Improved Impossible Differential Cryptanalysis of CLEFIA. 12 December 2007. 25 October 2010.
• Web site: Cihangir Tezcan. The Improbable Differential Attack: Cryptanalysis of Reduced Round CLEFIA. 8 August 2010. 25 October 2010.

External links

• CLEFIA website
• 256bit Ciphers - CLEFIA Reference implementation and derived code
• Sony Introduces CLEFIA
• Implementation of 128-bit CLEFIA codec and hash function

Notes and References

1. Book: Tezcan, Cihangir. Cihangir Tezcan. The Improbable Differential Attack: Cryptanalysis of Reduced-Round CLEFIA. Proceedings of INDOCRYPT, 2010 . https://archive.today/20130203003127/http://www.springerlink.com/content/6102840421522x70/. dead. 2013-02-03. Lecture Notes in Computer Science. Springer-Verlag.
2. Web site: Sony Develops "CLEFIA" - New Block Cipher Algorithm Based on State-of-the-art Design Technologies . 2007-03-26.
3. Web site: ISO/IEC 29192-2:2019, Information security - Lightweight cryptography - Part 2: Block ciphers.