Grand Cru is a symmetric block cryptographic algorithm in cryptography developed by Johan Borst of the Belgian Catholic University in Leuven based on the universally recognized Rijndael cipher and is its enhanced and deeply modified version. The algorithm uses a 128-bit key and a 128-bit (16 byte) block. The algorithm was sent as a participant in the Nessie contest.
| Grand cru | |
|---|---|
| Creator | Johan Borst |
| Created by | 2000 year |
| Published | 2000 year |
| Key size | 128 bit |
| Block size | 128 bit |
| Number of rounds | ten |
| Type of | Wildcard network |
The algorithm, like Rijndael, is not a cipher based on the Feistel Network and is implemented in accordance with the principles of the SPN structure.
Algorithm
Of the four data transformations in the round of the Rijndael cryptographic algorithm, there is only one operation - the subkey imposition by the XOR operation is key dependent. In the Grand Cru algorithm, an increase in the number of key transformations in a round of the algorithm enhances cryptographic strength with the same number of rounds. The Grand Cru round is a Rijndael round with the addition of two key operations instead of one keyless one.
Distinctive features of the algorithm:
- Multilayer security. The design is based on the de facto four different ciphers, each with its own subkey.
- Fixed key length and fixed block size: 128 bit
Reliability
During the participation of the algorithm in the NESSIE contest, no vulnerabilities or any attacks on the algorithm were detected. Nevertheless, the high cryptographic strength of this algorithm, according to experts of the competition, does not compensate for the low encryption speed, which has become an obstacle to election to the next stage of the competition.
According to its concept, the safety of Grand Cru is based on the safety of Rijndael, which is currently not in dispute. Theoretically, a cipher is safer, its mathematical structure is not so simple, and even while not feasible algebraic attacks on Rijndael are much less likely. According to the author, any attack on Grand Cru will be possible on Rijndael, and since there are no attacks on Rijndael, Grand Cru is safe.
At the same time, the algorithm is very difficult to implement and has a lower speed than AES . However, the code, unique and probably having a large margin of safety, was probably not widely distributed due to the lack of source code and any implementations - the author lived about a year after its publication and did not manage to publish them.