International Data Encryption Algorithm (IDEA)
The International Data Encryption Algorithm (IDEA) is a symmetric block cipher using a 64-bit block size and 128-bit keys.
- first proposed by James Massey and Xuijia Lai in 1991
- intended as a proposed replacement for DES
- consists of:
- 8 rounds of
- bitwise XORs
- addition module
- multiplication modulo
- a “half round” of output transformation and swap
- 8 rounds of
- only successful attack in 2012
- demonstrated effective reduction in cryptographic strength of about two bits (from 128 to 126-bits or,
to - practically, does not reduce security of the IDEA algorithm in use if properly implemented
- demonstrated effective reduction in cryptographic strength of about two bits (from 128 to 126-bits or,
- concern of proper implementation is regarding weak keys
- keys that have long repeating stretches of 0 or 1 bits
- became freely available as reference design in 2011