| Square | |
| Designers: | Joan Daemen, Vincent Rijmen |
| Publish Date: | 1997 |
| Derived To: | AES, CRYPTON, Twofish, Serpent |
| Key Size: | 128 bits |
| Block Size: | 128 bits |
| Structure: | substitution–permutation network |
| Rounds: | 8 |
In cryptography, Square (sometimes written SQUARE) is a block cipher invented by Joan Daemen and Vincent Rijmen. The design, published in 1997, is a forerunner to Rijndael, which has been adopted as the Advanced Encryption Standard. Square was introduced together with a new form of cryptanalysis discovered by Lars Knudsen, called the "Square attack".
The structure of Square is a substitution–permutation network with eight rounds, operating on 128-bit blocks and using a 128-bit key.
Square is not patented.