|Block sizes||variable, multiple of 32|
|Structure||generalized Feistel network|
|Best public cryptanalysis|
|differential cryptanalysis breaks most variants more easily than DES|
In cryptography, the Generalized DES Scheme (GDES or G-DES) is a variant of the DES symmetric-key block cipher designed with the intention of speeding up the encryption process while improving its security. The scheme was proposed by Ingrid Schaumuller-Bichl in 1981.
GDES generalizes the Feistel network structure of DES to larger block sizes. In each round, the DES round function is applied to the rightmost 32-bit subblock, and the result is XORed with all the other parts. Then the block is rotated 32 bits to the right.
- Eli Biham, Adi Shamir: Differential Cryptanalysis of DES-like Cryptosystems. CRYPTO 1990: 2-21
- Ingrid Schaumuller-Bichl, Zur Analyse des Data Encryption Standard und Synthese Verwandter Chiffriersysteme, Ph.D. Thesis, Linz university, May 1981. (In German).
- I. Schaumuller-Bichl, "On the Design and Analysis of New Cipher Systems Related to DES," Technical Report, Linz University, 1983.
- Schneier, Bruce (1996). Applied Cryptography, Second Edition. John Wiley & Sons. pp. 296. ISBN 0-471-11709-9.