Square (cipher)

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DesignersJoan Daemen, Vincent Rijmen
First published1997
SuccessorsAES, CRYPTON, Twofish, Serpent
Cipher detail
Key sizes128 bits
Block sizes128 bits
Structuresubstitution–permutation network

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.


  • Joan Daemen; Lars Knudsen; Vincent Rijmen (1997). The Block Cipher Square. Fast Software Encryption (FSE) 1997, Volume 1267 of Lecture Notes in Computer Science. Haifa, Israel: Springer-Verlag. pp. 149–165. CiteSeerX