Computer Security and Cryptography

9.3 THE DES S-BOXES, P-BOX, AND INITIAL PERMUTATION (IP)

Tables 9.4 to 9.11 specify the seven DES S-boxes, each with a 6-bit input (x₀, x₁, x₂, x₃, x₄, x₅, x₆) and a 4-bit output (y₀, y₁, y₂, y₃); each table contains 4 rows and 15 columns, where

• Bits (x₀, x₆) identify a row in the table, and
• bits (x₁, x₂, x₃, x₄) identify a column in the table.

TABLE 9.4 DES S-Box S[0]

TABLE 9.5 DES S-Box S[1]

TABLE 9.6 DES S-Box S[2]

TABLE 9.7 DES S-Box S[3]

TABLE 9.8 DES S-Box S[4]

TABLE 9.9 DES S-Box S[5]

TABLE 9.10 DES S-Box S[6]

TABLE 9.11 DES S-Box S[7]

My description of DES differs slightly from that given in [FIPS, 1988] in two respects:

• I use 0-index origin labeling; for example, a 64-bit plaintext ...