1 /*
2 * dlls/rsaen/rc2.c
3 * RC2 functions
4 *
5 * Copyright 2004 Michael Jung
6 * Based on public domain code by Tom St Denis (tomstdenis@iahu.ca)
7 *
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
21 */
22
23 /*
24 * This file contains code from the LibTomCrypt cryptographic
25 * library written by Tom St Denis (tomstdenis@iahu.ca). LibTomCrypt
26 * is in the public domain. The code in this file is tailored to
27 * special requirements. Take a look at http://libtomcrypt.org for the
28 * original version.
29 */
30
31 #include "tomcrypt.h"
32
33 /* 256-entry permutation table, probably derived somehow from pi */
34 static const unsigned char permute[256] = {
35 217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157,
36 198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162,
37 23,154, 89,245,135,179, 79, 19, 97, 69,109,141, 9,129,125, 50,
38 189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130,
39 84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220,
40 18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38,
41 111,191, 14,218, 70,105, 7, 87, 39,242, 29,155,188,148, 67, 3,
42 248, 17,199,246,144,239, 62,231, 6,195,213, 47,200,102, 30,215,
43 8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42,
44 150, 26,210,113, 90, 21, 73,116, 75,159,208, 94, 4, 24,164,236,
45 194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57,
46 153,124, 58,133, 35,184,180,122,252, 2, 54, 91, 37, 85,151, 49,
47 45, 93,250,152,227,138,146,174, 5,223, 41, 16,103,108,186,201,
48 211, 0,230,207,225,158,168, 44, 99, 22, 1, 63, 88,226,137,169,
49 13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46,
50 197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173
51 };
52
53 int rc2_setup(const unsigned char *key, int keylen, int bits, int rounds, rc2_key *rc2)
54 {
55 unsigned *xkey = rc2->xkey;
56 unsigned char tmp[128];
57 unsigned T8, TM;
58 int i;
59
60 if (keylen < 5 || keylen > 128) {
61 return CRYPT_INVALID_KEYSIZE;
62 }
63
64 if (rounds != 0 && rounds != 16) {
65 return CRYPT_INVALID_ROUNDS;
66 }
67
68 /* Following comment is from Eric Young's rc2 code: */
69 /* It has come to my attention that there are 2 versions of the RC2
70 * key schedule. One which is normal, and anther which has a hook to
71 * use a reduced key length.
72 * BSAFE uses the 'retarded' version. What I previously shipped is
73 * the same as specifying 1024 for the 'bits' parameter. BSAFE uses
74 * a version where the bits parameter is the same as len*8 */
75 /* Seems like MS uses the 'retarded' version, too.
76 * Adjust effective keylen bits */
77 if (bits <= 0) bits = keylen << 3;
78 if (bits > 1024) bits = 1024;
79
80 for (i = 0; i < keylen; i++) {
81 tmp[i] = key[i] & 255;
82 }
83
84 /* Phase 1: Expand input key to 128 bytes */
85 if (keylen < 128) {
86 for (i = keylen; i < 128; i++) {
87 tmp[i] = permute[(tmp[i - 1] + tmp[i - keylen]) & 255];
88 }
89 }
90
91 /* Phase 2 - reduce effective key size to "bits" */
92 /*bits = keylen<<3; */
93 T8 = (unsigned)(bits+7)>>3;
94 TM = (255 >> (unsigned)(7 & -bits));
95 tmp[128 - T8] = permute[tmp[128 - T8] & TM];
96 for (i = 127 - T8; i >= 0; i--) {
97 tmp[i] = permute[tmp[i + 1] ^ tmp[i + T8]];
98 }
99
100 /* Phase 3 - copy to xkey in little-endian order */
101 for (i = 0; i < 64; i++) {
102 xkey[i] = (unsigned)tmp[2*i] + ((unsigned)tmp[2*i+1] << 8);
103 }
104
105 return CRYPT_OK;
106 }
107
108 /**********************************************************************\
109 * Encrypt an 8-byte block of plaintext using the given key. *
110 \**********************************************************************/
111 void rc2_ecb_encrypt( const unsigned char *plain,
112 unsigned char *cipher,
113 rc2_key *rc2)
114 {
115 unsigned *xkey;
116 unsigned x76, x54, x32, x10, i;
117
118 xkey = rc2->xkey;
119
120 x76 = ((unsigned)plain[7] << 8) + (unsigned)plain[6];
121 x54 = ((unsigned)plain[5] << 8) + (unsigned)plain[4];
122 x32 = ((unsigned)plain[3] << 8) + (unsigned)plain[2];
123 x10 = ((unsigned)plain[1] << 8) + (unsigned)plain[0];
124
125 for (i = 0; i < 16; i++) {
126 x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4*i+0]) & 0xFFFF;
127 x10 = ((x10 << 1) | (x10 >> 15));
128
129 x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4*i+1]) & 0xFFFF;
130 x32 = ((x32 << 2) | (x32 >> 14));
131
132 x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4*i+2]) & 0xFFFF;
133 x54 = ((x54 << 3) | (x54 >> 13));
134
135 x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4*i+3]) & 0xFFFF;
136 x76 = ((x76 << 5) | (x76 >> 11));
137
138 if (i == 4 || i == 10) {
139 x10 = (x10 + xkey[x76 & 63]) & 0xFFFF;
140 x32 = (x32 + xkey[x10 & 63]) & 0xFFFF;
141 x54 = (x54 + xkey[x32 & 63]) & 0xFFFF;
142 x76 = (x76 + xkey[x54 & 63]) & 0xFFFF;
143 }
144 }
145
146 cipher[0] = (unsigned char)x10;
147 cipher[1] = (unsigned char)(x10 >> 8);
148 cipher[2] = (unsigned char)x32;
149 cipher[3] = (unsigned char)(x32 >> 8);
150 cipher[4] = (unsigned char)x54;
151 cipher[5] = (unsigned char)(x54 >> 8);
152 cipher[6] = (unsigned char)x76;
153 cipher[7] = (unsigned char)(x76 >> 8);
154 }
155
156 /**********************************************************************\
157 * Decrypt an 8-byte block of ciphertext using the given key. *
158 \**********************************************************************/
159 void rc2_ecb_decrypt( const unsigned char *cipher,
160 unsigned char *plain,
161 rc2_key *rc2)
162 {
163 unsigned x76, x54, x32, x10;
164 unsigned *xkey;
165 int i;
166
167 xkey = rc2->xkey;
168
169 x76 = ((unsigned)cipher[7] << 8) + (unsigned)cipher[6];
170 x54 = ((unsigned)cipher[5] << 8) + (unsigned)cipher[4];
171 x32 = ((unsigned)cipher[3] << 8) + (unsigned)cipher[2];
172 x10 = ((unsigned)cipher[1] << 8) + (unsigned)cipher[0];
173
174 for (i = 15; i >= 0; i--) {
175 if (i == 4 || i == 10) {
176 x76 = (x76 - xkey[x54 & 63]) & 0xFFFF;
177 x54 = (x54 - xkey[x32 & 63]) & 0xFFFF;
178 x32 = (x32 - xkey[x10 & 63]) & 0xFFFF;
179 x10 = (x10 - xkey[x76 & 63]) & 0xFFFF;
180 }
181
182 x76 = ((x76 << 11) | (x76 >> 5));
183 x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4*i+3])) & 0xFFFF;
184
185 x54 = ((x54 << 13) | (x54 >> 3));
186 x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4*i+2])) & 0xFFFF;
187
188 x32 = ((x32 << 14) | (x32 >> 2));
189 x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4*i+1])) & 0xFFFF;
190
191 x10 = ((x10 << 15) | (x10 >> 1));
192 x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4*i+0])) & 0xFFFF;
193 }
194
195 plain[0] = (unsigned char)x10;
196 plain[1] = (unsigned char)(x10 >> 8);
197 plain[2] = (unsigned char)x32;
198 plain[3] = (unsigned char)(x32 >> 8);
199 plain[4] = (unsigned char)x54;
200 plain[5] = (unsigned char)(x54 >> 8);
201 plain[6] = (unsigned char)x76;
202 plain[7] = (unsigned char)(x76 >> 8);
203 }
204
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