SOME DESIGN CRITERIA FOR FEISTEL-CIPHER KEY SCHEDULES
Richard Outerbridge · Cryptologia · 1986
The ANSI Data Encryption Algorithm (DEA) X3.92-1981, is probably a Feistel cipher. In considering how to expand the key of the DEA from 56 to 64 bits two similar ciphers are examined, and several design criteria inferred. As an example of their application, a 64-bit key schedule for the DEA is presented.