The Data Encryption Standard (DES)

The Data Encryption Standard (DES) [31] has been around for more than 25 years. DES was an outcome of a call for primitives in 1974 which didn’t result in many serious candidates except for a predecessor of DES, Lucifer [15, 35] designed by IBM around 1971. It took another year for a joint IBM–NSA effort to turn Lucifer into DES. The structure of Lucifer was significantly altered and since the design rationale was never made public and the secret key size was reduced from 128-bit to 56-bits this initially resulted in controversy, and some distrust among the public. However, in spite of all the controversy it is hard to underestimate the role of DES. DES was one of the first commercially developed (as opposed to government developed) ciphers whose structure was fully published. This effectively created a community of researchers who could analyse it and propose their own designs. This lead to a wave of public interest in cryptography, from which much of the cryptography as we know it today was born.