I’ve spoken of more than a couple ciphers (cryptographic algorithms) already such as DES, 3DES, RC4, RC5 and RC6. One cipher that I neglected to mention is IDEA (International Date Encryption Algorithm).

IDEA is a block cipher that appeared in 1990. It was developed at the Swiss Federal Institute of Technology by Xuenjia Lai and James Massey. IDEA has a 128-bit key which is more than twice the size of the 56-bit key used in DEs and 3DES’

IDEA is called a block cipher because it operates on 64-bit blocks using a 128-bit key. Part of its operations includes exclusive-ORs, addition modulus and multiplication modulus. It is thought to be immune to differential cryptanalysis under certain conditions. Over the years it has lost its luster due to faster algorithms, issues with patents and little progress in its cryptanalysis.

However, it should be noted that the TLS (Transport Layer Security) group submitted a paper – http://www.ietf.org/internet-drafts/draft-ietf-tls-des-idea-02.txt -  and recommended that DES and IDEA not be used in Transport Layer Security 1.2 main specification. Their reasons for not recommending DES and IDEA include:

• IDEA is a rarely used code and thus is prone to security and interoperability problems
• Most implementations either do not support it, do not enable it by default or do not negotiate it when other algorithms are available.

In 1998, Fortress Technologies became the sole U.S. distributor of the IDEA encryption algorithm by signing a licensing agreement with ASCOM Systec, Ltd., the Swiss conglomerate that owns the IDEA patent.

Ascom is the sole owner of IDEA and holds all intellectual property rights for it. MediaCrypt is the worldwide distributor of the IDEA license. An IDEA license can be purchased from MediaCrypt but at the time of this writing, the MediaCrypt web page had been offline for months.  You can try to contact MediaCrypt AG via the address given in their domain registration. See http://whois.domaintools.com/mediacrypt.com.You also might try contacting someone at Ascom: http://www.ascom.com

The Network Working Group Request For Comments, RFC3058 – “Use of the IDEA Encryption Algorithm in CMS” explains how to incorporate IDEA in Content Management Systems (CMS) and S/MIME (Secure / Multipurpose Internet Mail Extensions) as an additional strong algorithm for symmetric encryption.

As it is, in 2004 TrueCrypt software – free open source on-the-fly disk encryption software – removed IDEA from its product suite.