1 /**********************************************************************\
2 * To commemorate the 1996 RSA Data Security Conference, the following *
3 * code is released into the public domain by its author. Prost! *
5 * This cipher uses 16-bit words and little-endian byte ordering. *
6 * I wonder which processor it was optimized for? *
8 * Thanks to CodeView, SoftIce, and D86 for helping bring this code to *
10 \**********************************************************************/
16 const struct _cipher_descriptor rc2_desc = {
27 /**********************************************************************\
28 * Expand a variable-length user key (between 1 and 128 bytes) to a *
29 * 64-short working rc2 key, of at most "bits" effective key bits. *
30 * The effective key bits parameter looks like an export control hack. *
31 * For normal use, it should always be set to 1024. For convenience, *
32 * zero is accepted as an alias for 1024. *
33 \**********************************************************************/
35 /* 256-entry permutation table, probably derived somehow from pi */
36 static const unsigned char permute[256] = {
37 217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157,
38 198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162,
39 23,154, 89,245,135,179, 79, 19, 97, 69,109,141, 9,129,125, 50,
40 189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130,
41 84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220,
42 18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38,
43 111,191, 14,218, 70,105, 7, 87, 39,242, 29,155,188,148, 67, 3,
44 248, 17,199,246,144,239, 62,231, 6,195,213, 47,200,102, 30,215,
45 8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42,
46 150, 26,210,113, 90, 21, 73,116, 75,159,208, 94, 4, 24,164,236,
47 194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57,
48 153,124, 58,133, 35,184,180,122,252, 2, 54, 91, 37, 85,151, 49,
49 45, 93,250,152,227,138,146,174, 5,223, 41, 16,103,108,186,201,
50 211, 0,230,207,225,158,168, 44, 99, 22, 1, 63, 88,226,137,169,
51 13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46,
52 197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173
55 int rc2_setup(const unsigned char *key, int keylen, int rounds, symmetric_key *skey)
57 unsigned *xkey = skey->rc2.xkey;
58 unsigned char tmp[128];
63 _ARGCHK(skey != NULL);
65 if (keylen < 8 || keylen > 128) {
66 return CRYPT_INVALID_KEYSIZE;
69 if (rounds != 0 && rounds != 16) {
70 return CRYPT_INVALID_ROUNDS;
73 for (i = 0; i < keylen; i++) {
77 /* Phase 1: Expand input key to 128 bytes */
79 for (i = keylen; i < 128; i++) {
80 tmp[i] = permute[(int)((tmp[i - 1] + tmp[i - keylen]) & 255)];
84 /* Phase 2 - reduce effective key size to "bits" */
86 T8 = (unsigned)(bits+7)>>3;
87 TM = (255 >> (unsigned)(7 & -bits));
88 tmp[128 - T8] = permute[(int)(tmp[128 - T8] & TM)];
89 for (i = 127 - T8; i >= 0; i--) {
90 tmp[i] = permute[(int)(tmp[i + 1] ^ tmp[i + T8])];
93 /* Phase 3 - copy to xkey in little-endian order */
96 xkey[i] = (unsigned)tmp[2*i] + ((unsigned)tmp[2*i+1] << 8);
100 zeromem(tmp, sizeof(tmp));
106 /**********************************************************************\
107 * Encrypt an 8-byte block of plaintext using the given key. *
108 \**********************************************************************/
110 static void _rc2_ecb_encrypt( const unsigned char *plain,
111 unsigned char *cipher,
114 void rc2_ecb_encrypt( const unsigned char *plain,
115 unsigned char *cipher,
119 unsigned *xkey = skey->rc2.xkey;
120 unsigned x76, x54, x32, x10, i;
122 _ARGCHK(plain != NULL);
123 _ARGCHK(cipher != NULL);
124 _ARGCHK(skey != NULL);
126 x76 = ((unsigned)plain[7] << 8) + (unsigned)plain[6];
127 x54 = ((unsigned)plain[5] << 8) + (unsigned)plain[4];
128 x32 = ((unsigned)plain[3] << 8) + (unsigned)plain[2];
129 x10 = ((unsigned)plain[1] << 8) + (unsigned)plain[0];
131 for (i = 0; i < 16; i++) {
132 x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4*i+0]) & 0xFFFF;
133 x10 = ((x10 << 1) | (x10 >> 15)) & 0xFFFF;
135 x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4*i+1]) & 0xFFFF;
136 x32 = ((x32 << 2) | (x32 >> 14)) & 0xFFFF;
138 x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4*i+2]) & 0xFFFF;
139 x54 = ((x54 << 3) | (x54 >> 13)) & 0xFFFF;
141 x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4*i+3]) & 0xFFFF;
142 x76 = ((x76 << 5) | (x76 >> 11)) & 0xFFFF;
144 if (i == 4 || i == 10) {
145 x10 = (x10 + xkey[x76 & 63]) & 0xFFFF;
146 x32 = (x32 + xkey[x10 & 63]) & 0xFFFF;
147 x54 = (x54 + xkey[x32 & 63]) & 0xFFFF;
148 x76 = (x76 + xkey[x54 & 63]) & 0xFFFF;
152 cipher[0] = (unsigned char)x10;
153 cipher[1] = (unsigned char)(x10 >> 8);
154 cipher[2] = (unsigned char)x32;
155 cipher[3] = (unsigned char)(x32 >> 8);
156 cipher[4] = (unsigned char)x54;
157 cipher[5] = (unsigned char)(x54 >> 8);
158 cipher[6] = (unsigned char)x76;
159 cipher[7] = (unsigned char)(x76 >> 8);
163 void rc2_ecb_encrypt( const unsigned char *plain,
164 unsigned char *cipher,
167 _rc2_ecb_encrypt(plain, cipher, skey);
168 burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 5);
172 /**********************************************************************\
173 * Decrypt an 8-byte block of ciphertext using the given key. *
174 \**********************************************************************/
177 static void _rc2_ecb_decrypt( const unsigned char *cipher,
178 unsigned char *plain,
181 void rc2_ecb_decrypt( const unsigned char *cipher,
182 unsigned char *plain,
186 unsigned x76, x54, x32, x10;
187 unsigned *xkey = skey->rc2.xkey;
190 _ARGCHK(plain != NULL);
191 _ARGCHK(cipher != NULL);
192 _ARGCHK(skey != NULL);
194 x76 = ((unsigned)cipher[7] << 8) + (unsigned)cipher[6];
195 x54 = ((unsigned)cipher[5] << 8) + (unsigned)cipher[4];
196 x32 = ((unsigned)cipher[3] << 8) + (unsigned)cipher[2];
197 x10 = ((unsigned)cipher[1] << 8) + (unsigned)cipher[0];
199 for (i = 15; i >= 0; i--) {
200 if (i == 4 || i == 10) {
201 x76 = (x76 - xkey[x54 & 63]) & 0xFFFF;
202 x54 = (x54 - xkey[x32 & 63]) & 0xFFFF;
203 x32 = (x32 - xkey[x10 & 63]) & 0xFFFF;
204 x10 = (x10 - xkey[x76 & 63]) & 0xFFFF;
207 x76 = ((x76 << 11) | (x76 >> 5)) & 0xFFFF;
208 x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4*i+3])) & 0xFFFF;
210 x54 = ((x54 << 13) | (x54 >> 3)) & 0xFFFF;
211 x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4*i+2])) & 0xFFFF;
213 x32 = ((x32 << 14) | (x32 >> 2)) & 0xFFFF;
214 x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4*i+1])) & 0xFFFF;
216 x10 = ((x10 << 15) | (x10 >> 1)) & 0xFFFF;
217 x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4*i+0])) & 0xFFFF;
220 plain[0] = (unsigned char)x10;
221 plain[1] = (unsigned char)(x10 >> 8);
222 plain[2] = (unsigned char)x32;
223 plain[3] = (unsigned char)(x32 >> 8);
224 plain[4] = (unsigned char)x54;
225 plain[5] = (unsigned char)(x54 >> 8);
226 plain[6] = (unsigned char)x76;
227 plain[7] = (unsigned char)(x76 >> 8);
231 void rc2_ecb_decrypt( const unsigned char *cipher,
232 unsigned char *plain,
235 _rc2_ecb_decrypt(cipher, plain, skey);
236 burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 4 + sizeof(int));
245 static const struct {
247 unsigned char key[16], pt[8], ct[8];
251 { 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
252 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
253 { 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
254 { 0x30, 0x64, 0x9e, 0xdf, 0x9b, 0xe7, 0xd2, 0xc2 }
258 { 0x88, 0xbc, 0xa9, 0x0e, 0x90, 0x87, 0x5a, 0x7f,
259 0x0f, 0x79, 0xc3, 0x84, 0x62, 0x7b, 0xaf, 0xb2 },
260 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
261 { 0x22, 0x69, 0x55, 0x2a, 0xb0, 0xf8, 0x5c, 0xa6 }
266 unsigned char buf[2][8];
268 for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
269 zeromem(buf, sizeof(buf));
270 if ((err = rc2_setup(tests[x].key, tests[x].keylen, 0, &skey)) != CRYPT_OK) {
274 rc2_ecb_encrypt(tests[x].pt, buf[0], &skey);
275 rc2_ecb_decrypt(buf[0], buf[1], &skey);
277 if (memcmp(buf[0], tests[x].ct, 8) != 0 || memcmp(buf[1], tests[x].pt, 8) != 0) {
278 return CRYPT_FAIL_TESTVECTOR;
285 int rc2_keysize(int *keysize)
287 _ARGCHK(keysize != NULL);
289 return CRYPT_INVALID_KEYSIZE;
290 } else if (*keysize > 128) {