1 // GoGOST -- Pure Go GOST cryptographic functions library
2 // Copyright (C) 2015-2019 Sergey Matveev <stargrave@stargrave.org>
4 // This program is free software: you can redistribute it and/or modify
5 // it under the terms of the GNU General Public License as published by
6 // the Free Software Foundation, version 3 of the License.
8 // This program is distributed in the hope that it will be useful,
9 // but WITHOUT ANY WARRANTY; without even the implied warranty of
10 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 // GNU General Public License for more details.
13 // You should have received a copy of the GNU General Public License
14 // along with this program. If not, see <http://www.gnu.org/licenses/>.
16 // GOST 34.12-2015 128-bit (Кузнечик (Kuznechik)) block cipher.
25 lc [BlockSize]byte = [BlockSize]byte{
26 148, 32, 133, 16, 194, 192, 1, 251, 1, 192, 194, 16,
29 pi [256]byte = [256]byte{
30 252, 238, 221, 17, 207, 110, 49, 22, 251, 196, 250,
31 218, 35, 197, 4, 77, 233, 119, 240, 219, 147, 46,
32 153, 186, 23, 54, 241, 187, 20, 205, 95, 193, 249,
33 24, 101, 90, 226, 92, 239, 33, 129, 28, 60, 66, 139,
34 1, 142, 79, 5, 132, 2, 174, 227, 106, 143, 160, 6,
35 11, 237, 152, 127, 212, 211, 31, 235, 52, 44, 81,
36 234, 200, 72, 171, 242, 42, 104, 162, 253, 58, 206,
37 204, 181, 112, 14, 86, 8, 12, 118, 18, 191, 114, 19,
38 71, 156, 183, 93, 135, 21, 161, 150, 41, 16, 123,
39 154, 199, 243, 145, 120, 111, 157, 158, 178, 177,
40 50, 117, 25, 61, 255, 53, 138, 126, 109, 84, 198,
41 128, 195, 189, 13, 87, 223, 245, 36, 169, 62, 168,
42 67, 201, 215, 121, 214, 246, 124, 34, 185, 3, 224,
43 15, 236, 222, 122, 148, 176, 188, 220, 232, 40, 80,
44 78, 51, 10, 74, 167, 151, 96, 115, 30, 0, 98, 68,
45 26, 184, 56, 130, 100, 159, 38, 65, 173, 69, 70,
46 146, 39, 94, 85, 47, 140, 163, 165, 125, 105, 213,
47 149, 59, 7, 88, 179, 64, 134, 172, 29, 247, 48, 55,
48 107, 228, 136, 217, 231, 137, 225, 27, 131, 73, 76,
49 63, 248, 254, 141, 83, 170, 144, 202, 216, 133, 97,
50 32, 113, 103, 164, 45, 43, 9, 91, 203, 155, 37, 208,
51 190, 229, 108, 82, 89, 166, 116, 210, 230, 244, 180,
52 192, 209, 102, 175, 194, 57, 75, 99, 182,
55 cBlk [32]*[BlockSize]byte
58 func gf(a, b byte) (c byte) {
73 func l(blk *[BlockSize]byte, rounds int) {
76 for ; rounds > 0; rounds-- {
78 for i = 14; i >= 0; i-- {
80 t ^= gf(blk[i], lc[i])
86 func lInv(blk *[BlockSize]byte) {
89 for n := 0; n < BlockSize; n++ {
91 for i = 0; i < 15; i++ {
93 t ^= gf(blk[i], lc[i])
100 piInvP := new([256]byte)
101 for i := 0; i < 256; i++ {
102 piInvP[int(pi[i])] = byte(i)
105 CP := new([32]*[BlockSize]byte)
106 for i := 0; i < 32; i++ {
107 CP[i] = new([BlockSize]byte)
108 CP[i][15] = byte(i) + 1
114 func s(blk *[BlockSize]byte) {
115 for i := 0; i < BlockSize; i++ {
116 blk[i] = pi[int(blk[i])]
120 func xor(dst, src1, src2 *[BlockSize]byte) {
121 for i := 0; i < BlockSize; i++ {
122 dst[i] = src1[i] ^ src2[i]
127 ks [10]*[BlockSize]byte
130 func (c *Cipher) BlockSize() int {
134 func NewCipher(key []byte) *Cipher {
135 if len(key) != KeySize {
136 panic("invalid key size")
138 ks := new([10]*[BlockSize]byte)
139 kr0 := new([BlockSize]byte)
140 kr1 := new([BlockSize]byte)
141 krt := new([BlockSize]byte)
142 copy(kr0[:], key[:BlockSize])
143 copy(kr1[:], key[BlockSize:])
144 ks[0] = new([BlockSize]byte)
145 ks[1] = new([BlockSize]byte)
146 copy(ks[0][:], kr0[:])
147 copy(ks[1][:], kr1[:])
148 for i := 0; i < 4; i++ {
149 for j := 0; j < 8; j++ {
150 xor(krt, kr0, cBlk[8*i+j])
157 ks[2+2*i] = new([BlockSize]byte)
158 copy(ks[2+2*i][:], kr0[:])
159 ks[2+2*i+1] = new([BlockSize]byte)
160 copy(ks[2+2*i+1][:], kr1[:])
165 func (c *Cipher) Encrypt(dst, src []byte) {
166 blk := new([BlockSize]byte)
168 for i := 0; i < 9; i++ {
169 xor(blk, blk, c.ks[i])
173 xor(blk, blk, c.ks[9])
174 copy(dst[:BlockSize], blk[:])
177 func (c *Cipher) Decrypt(dst, src []byte) {
178 blk := new([BlockSize]byte)
181 for i := 9; i > 0; i-- {
182 xor(blk, blk, c.ks[i])
184 for n = 0; n < BlockSize; n++ {
185 blk[n] = piInv[int(blk[n])]
188 xor(blk, blk, c.ks[0])
189 copy(dst[:BlockSize], blk[:])