International Data Encryption Algorithm

In cryptography, the International Data Encryption Algorithm (IDEA), originally called Improved Proposed Encryption Standard (IPES), is a symmetric-key block cipher designed by James Massey of ETH Zurich and Xuejia Lai and was first described in 1991. The algorithm was intended as a replacement for the Data Encryption Standard (DES). IDEA is a minor revision of an earlier cipher, the Proposed Encryption Standard (PES).

The cipher was designed under a research contract with the Hasler Foundation, which became part of Ascom-Tech AG. The cipher was patented in a number of countries but was freely available for non-commercial use. The name "IDEA" is also a trademark. The last patents expired in 2012, and IDEA is now patent-free and thus completely free for all uses.

IDEA was used in Pretty Good Privacy (PGP) v2.0 and was incorporated after the original cipher used in v1.0, BassOmatic, was found to be insecure. IDEA is an optional algorithm in the OpenPGP standard.

Operation

IDEA is a way to keep information safe by using a special method to mix up the data. It works on pieces of data called "blocks" that are 64 bits long and uses a 128-bit key to lock and unlock them. The process has 8 main steps, called rounds, and one final step called a half-round.

During these steps, IDEA mixes the data using three different math operations: XOR, addition, and multiplication. These operations make it very hard for someone to figure out the secret key just by looking at the mixed-up data. After the 8 rounds, there is a final half-round to finish the mixing.

Security

IDEA was created to be a strong way to keep information safe. Experts studied it and found it to be very strong against certain types of attacks. Even though some smarter ways to try to break it were found later, IDEA was still considered quite safe for most uses.

There were some special types of keys that made IDEA a bit weaker, but these were very rare and not a big problem for most people using it. Experts suggested small changes to make it even safer.

Availability

The International Data Encryption Algorithm (IDEA) was first patented in Switzerland in 1990, and later patents were filed internationally. Eventually, patents were granted in many countries including Austria, France, Germany, Italy, the Netherlands, Spain, Sweden, Switzerland, the United Kingdom, the United States, and Japan.

Today, a company called MediaCrypt AG offers a newer version called IDEA NXT, which was released in 2005. This new version is sometimes referred to as FOX.

Literature

The International Data Encryption Algorithm (IDEA) has been studied and written about by many experts. In 1991, Xuejia Lai and James Massey proposed IDEA as a new way to protect information. Their work appeared in a book about advances in cryptography. Later, researchers continued to explore IDEA's strengths and weaknesses, contributing to our understanding of how to keep data safe.