General  

Designers  Johan Borst 
First published  2000 
Derived from  Rijndael 
Cipher detail  
Key sizes  128 bits 
Block sizes  128 bits 
Structure  Substitutionpermutation network 
Rounds  10 
In cryptography, Grand Cru is a block cipher invented in 2000 by Johan Borst. It was submitted to the NESSIE project, but was not selected.
Grand Cru is a 10round substitutionpermutation network based largely on Rijndael (or AES). It replaces a number of Rijndael's unkeyed operations with keydependent ones, in a way consistent with the security purposes of each operation. The intent is to produce a cipher at least as secure as Rijndael, and perhaps much more secure. The block size and key size are both 128 bits, and the key schedule is the same as Rijndael's.
Grand Cru is designed on the principle of multiple layered security. It is equivalent to a chain of 4 subciphers with independent keys, such that if 3 of the keys are known, the remaining cipher should still be secure.
