1// Copyright 2010 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Package des implements the Data Encryption Standard (DES) and the
6// Triple Data Encryption Algorithm (TDEA) as defined
7// in U.S. Federal Information Processing Standards Publication 46-3.
8package des
9
10// Used to perform an initial permutation of a 64-bit input block.
11var initialPermutation = [64]byte{
12	6, 14, 22, 30, 38, 46, 54, 62,
13	4, 12, 20, 28, 36, 44, 52, 60,
14	2, 10, 18, 26, 34, 42, 50, 58,
15	0, 8, 16, 24, 32, 40, 48, 56,
16	7, 15, 23, 31, 39, 47, 55, 63,
17	5, 13, 21, 29, 37, 45, 53, 61,
18	3, 11, 19, 27, 35, 43, 51, 59,
19	1, 9, 17, 25, 33, 41, 49, 57,
20}
21
22// Used to perform a final permutation of a 4-bit preoutput block. This is the
23// inverse of initialPermutation
24var finalPermutation = [64]byte{
25	24, 56, 16, 48, 8, 40, 0, 32,
26	25, 57, 17, 49, 9, 41, 1, 33,
27	26, 58, 18, 50, 10, 42, 2, 34,
28	27, 59, 19, 51, 11, 43, 3, 35,
29	28, 60, 20, 52, 12, 44, 4, 36,
30	29, 61, 21, 53, 13, 45, 5, 37,
31	30, 62, 22, 54, 14, 46, 6, 38,
32	31, 63, 23, 55, 15, 47, 7, 39,
33}
34
35// Used to expand an input block of 32 bits, producing an output block of 48
36// bits.
37var expansionFunction = [48]byte{
38	0, 31, 30, 29, 28, 27, 28, 27,
39	26, 25, 24, 23, 24, 23, 22, 21,
40	20, 19, 20, 19, 18, 17, 16, 15,
41	16, 15, 14, 13, 12, 11, 12, 11,
42	10, 9, 8, 7, 8, 7, 6, 5,
43	4, 3, 4, 3, 2, 1, 0, 31,
44}
45
46// Yields a 32-bit output from a 32-bit input
47var permutationFunction = [32]byte{
48	16, 25, 12, 11, 3, 20, 4, 15,
49	31, 17, 9, 6, 27, 14, 1, 22,
50	30, 24, 8, 18, 0, 5, 29, 23,
51	13, 19, 2, 26, 10, 21, 28, 7,
52}
53
54// Used in the key schedule to select 56 bits
55// from a 64-bit input.
56var permutedChoice1 = [56]byte{
57	7, 15, 23, 31, 39, 47, 55, 63,
58	6, 14, 22, 30, 38, 46, 54, 62,
59	5, 13, 21, 29, 37, 45, 53, 61,
60	4, 12, 20, 28, 1, 9, 17, 25,
61	33, 41, 49, 57, 2, 10, 18, 26,
62	34, 42, 50, 58, 3, 11, 19, 27,
63	35, 43, 51, 59, 36, 44, 52, 60,
64}
65
66// Used in the key schedule to produce each subkey by selecting 48 bits from
67// the 56-bit input
68var permutedChoice2 = [48]byte{
69	42, 39, 45, 32, 55, 51, 53, 28,
70	41, 50, 35, 46, 33, 37, 44, 52,
71	30, 48, 40, 49, 29, 36, 43, 54,
72	15, 4, 25, 19, 9, 1, 26, 16,
73	5, 11, 23, 8, 12, 7, 17, 0,
74	22, 3, 10, 14, 6, 20, 27, 24,
75}
76
77// 8 S-boxes composed of 4 rows and 16 columns
78// Used in the DES cipher function
79var sBoxes = [8][4][16]uint8{
80	// S-box 1
81	{
82		{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7},
83		{0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8},
84		{4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0},
85		{15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13},
86	},
87	// S-box 2
88	{
89		{15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10},
90		{3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5},
91		{0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15},
92		{13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9},
93	},
94	// S-box 3
95	{
96		{10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8},
97		{13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1},
98		{13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7},
99		{1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12},
100	},
101	// S-box 4
102	{
103		{7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15},
104		{13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9},
105		{10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4},
106		{3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14},
107	},
108	// S-box 5
109	{
110		{2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9},
111		{14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6},
112		{4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14},
113		{11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3},
114	},
115	// S-box 6
116	{
117		{12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11},
118		{10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8},
119		{9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6},
120		{4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13},
121	},
122	// S-box 7
123	{
124		{4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1},
125		{13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6},
126		{1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2},
127		{6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12},
128	},
129	// S-box 8
130	{
131		{13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7},
132		{1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2},
133		{7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8},
134		{2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11},
135	},
136}
137
138// Size of left rotation per round in each half of the key schedule
139var ksRotations = [16]uint8{1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1}
140