International Data Encryption Algorithm

In cryptography, the International Data Encryption Algorithm (IDEA) is a symmetric-key block cipher. It was designed by James Massey of ETH Zurich and Xuejia Lai and first described in 1991. The algorithm was meant to replace the Data Encryption Standard (DES). IDEA is a small change to an earlier cipher called the Proposed Encryption Standard (PES).

The cipher was created for a research project with the Hasler Foundation, which later became part of Ascom-Tech AG. IDEA was patented in some countries but could be used freely for non-commercial purposes. The name "IDEA" is also a trademark. The last patents ended in 2012, making IDEA free to use for everyone.

IDEA was used in Pretty Good Privacy (PGP) version 2.0. It was added after the original cipher in version 1.0, BassOmatic, was found to be weak. IDEA is one of the optional algorithms in the OpenPGP standard.

Operation

IDEA is a way to keep information safe by mixing 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. After the 8 rounds, there is a final half-round to finish the mixing.

Security

IDEA was made to keep information safe. Experts looked at it and found it to be very strong for stopping some kinds of attacks. Later, some new ways to try to break it were found, but IDEA was still thought to be safe for most uses.

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

Availability

The International Data Encryption Algorithm (IDEA) was first patented in Switzerland in 1990. After that, patents were filed 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. This new version was released in 2005 and is sometimes called FOX.

Literature

The International Data Encryption Algorithm (IDEA) has been studied by many experts. In 1991, Xuejia Lai and James Massey created IDEA to help protect information. Their work was in a book about advances in cryptography. Later, other researchers looked at IDEA to learn more about keeping data safe.