In cryptography, the Generalized DES Scheme (G-DES or GDES) is a variant of the DES block cipher designed to speed-up the encryption. The scheme was proposed by Ingrid Schaumuller-Bichl in 1981. In 1990, Eli Biham and Adi Shamir showed that G-DES was vulnerable to differential cryptanalysis and that any G-DES variant faster than DES is also less secure than DES.

References

• 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.