International Data Encryption Algorithm (IDEA) is a symmetric encryption method that was developed from the Proposed Encryption Standard ( PES) and, like the Data Encryption Standard( DES), works with plaintext blocks of 64 bits in length and a key length of 128 bits.
In the IDEA algorithm, data is encrypted by repeating the same operations multiple times. Unlike DES encryption, which uses 16 repetitions, only 8 repetitions take place in IDEA, which reduces the computing time. The block cipher IDEA is based on a mixture of three different algebraic operations: An XOR operation, an addition with modulo `2^16` and a multiplication with modulo `2^16 +1`.
IDEA was developed in the early 1990s by Xuejia Lai and L. Massey, is used within Pretty Good Privacy( PGP), provides higher security than the Data Encryption Standard (DES), and is a possible replacement for it.