Iraqi block cipher
In cryptography, the Iraqi block cipher was a block cipher published in C source code form by anonymous FTP upload around July 1999, and widely distributed on Usenet. It is a five round unbalanced Feistel cipher operating on a 256 bit block with a 160 bit key.

A comment suggests that it is of Iraqi origin. However, like the S-1 block cipher, it is generally regarded as a hoax, although of lesser quality than S-1. Although the comment suggests that it is Iraqi in origin, all comments, variable and function names and printed strings are in English rather than Arabic; the code is fairly inefficient (including some pointless operations), and the cipher's security may be flawed (no proof).

Because it has a constant key schedule the cipher is vulnerable to a slide attack. However, it may take 264 chosen texts to create a single slid pair, which would make the attack unfeasible. It also has many fixed points, although that is not necessarily a problem, except possibly for hashing modes. No public attack is currently available. As with S-1, it was David Wagner who first spotted the security flaws.

References

External links
 Source code for the cipher
 File encryption with IBC in ECB and CBC Mode

Block ciphers
Internet hoaxes
1999 hoaxes