Cryptography: What are the Controversy surrounding Data Encryption Standard (DES)

•Before its adoption as a standard, the proposed DES was subjected to intense criticism, which has not subsided to this day.

•Two areas drew the critics’ fire.

1.First, the key length in IBM’s original LUCIFER algorithm was 128 bits, but that of the proposed system was only 56 bits, an enormous reduction in key size of 72 bits.

–Critics feared that this key length was too short to withstand brute-force attacks.

2.The second area of concern was that the design criteria for the internal structure of DES, the S-boxes, were classified.

–Thus, users could not be sure that the internal structure of DES was free of any hidden weak points that would enable NSA to decipher messages without benefit of the key.

–Subsequent events, particularly the recent work on differential cryptanalysis, seem to indicate that DES has a very strong internal structure.

–Furthermore, according to IBM participants, the only changes that were made to the proposal were changes to the S-boxes, suggested by NSA, that removed vulnerabilities identified in the course of the evaluation process.