sshsha.c

   1 /*
   2  * SHA1 hash algorithm. Used in SSH-2 as a MAC, and the transform is
   3  * also used as a `stirring' function for the PuTTY random number
   4  * pool. Implemented directly from the specification by Simon
   5  * Tatham.
   6  */
   7
   8 #include "ssh.h"
   9
  10 /* ----------------------------------------------------------------------
  11  * Core SHA algorithm: processes 16-word blocks into a message digest.
  12  */
  13
  14 #define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
  15
  16 static void SHA_Core_Init(uint32 h[5])
  17 {
  18     h[0] = 0x67452301;
  19     h[1] = 0xefcdab89;
  20     h[2] = 0x98badcfe;
  21     h[3] = 0x10325476;
  22     h[4] = 0xc3d2e1f0;
  23 }
  24
  25 void SHATransform(word32 * digest, word32 * block)
  26 {
  27     word32 w[80];
  28     word32 a, b, c, d, e;
  29     int t;
  30
  31     for (t = 0; t < 16; t++)
  32         w[t] = block[t];
  33
  34     for (t = 16; t < 80; t++) {
  35         word32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16];
  36         w[t] = rol(tmp, 1);
  37     }
  38
  39     a = digest[0];
  40     b = digest[1];
  41     c = digest[2];
  42     d = digest[3];
  43     e = digest[4];
  44
  45     for (t = 0; t < 20; t++) {
  46         word32 tmp =
  47             rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999;
  48         e = d;
  49         d = c;
  50         c = rol(b, 30);
  51         b = a;
  52         a = tmp;
  53     }
  54     for (t = 20; t < 40; t++) {
  55         word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1;
  56         e = d;
  57         d = c;
  58         c = rol(b, 30);
  59         b = a;
  60         a = tmp;
  61     }
  62     for (t = 40; t < 60; t++) {
  63         word32 tmp = rol(a,
  64                          5) + ((b & c) | (b & d) | (c & d)) + e + w[t] +
  65             0x8f1bbcdc;
  66         e = d;
  67         d = c;
  68         c = rol(b, 30);
  69         b = a;
  70         a = tmp;
  71     }
  72     for (t = 60; t < 80; t++) {
  73         word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6;
  74         e = d;
  75         d = c;
  76         c = rol(b, 30);
  77         b = a;
  78         a = tmp;
  79     }
  80
  81     digest[0] += a;
  82     digest[1] += b;
  83     digest[2] += c;
  84     digest[3] += d;
  85     digest[4] += e;
  86 }
  87
  88 /* ----------------------------------------------------------------------
  89  * Outer SHA algorithm: take an arbitrary length byte string,
  90  * convert it into 16-word blocks with the prescribed padding at
  91  * the end, and pass those blocks to the core SHA algorithm.
  92  */
  93
  94 void SHA_Init(SHA_State * s)
  95 {
  96     SHA_Core_Init(s->h);
  97     s->blkused = 0;
  98     s->lenhi = s->lenlo = 0;
  99 }
 100
 101 void SHA_Bytes(SHA_State * s, void *p, int len)
 102 {
 103     unsigned char *q = (unsigned char *) p;
 104     uint32 wordblock[16];
 105     uint32 lenw = len;
 106     int i;
 107
 108     /*
 109      * Update the length field.
 110      */
 111     s->lenlo += lenw;
 112     s->lenhi += (s->lenlo < lenw);
 113
 114     if (s->blkused && s->blkused + len < 64) {
 115         /*
 116          * Trivial case: just add to the block.
 117          */
 118         memcpy(s->block + s->blkused, q, len);
 119         s->blkused += len;
 120     } else {
 121         /*
 122          * We must complete and process at least one block.
 123          */
 124         while (s->blkused + len >= 64) {
 125             memcpy(s->block + s->blkused, q, 64 - s->blkused);
 126             q += 64 - s->blkused;
 127             len -= 64 - s->blkused;
 128             /* Now process the block. Gather bytes big-endian into words */
 129             for (i = 0; i < 16; i++) {
 130                 wordblock[i] =
 131                     (((uint32) s->block[i * 4 + 0]) << 24) |
 132                     (((uint32) s->block[i * 4 + 1]) << 16) |
 133                     (((uint32) s->block[i * 4 + 2]) << 8) |
 134                     (((uint32) s->block[i * 4 + 3]) << 0);
 135             }
 136             SHATransform(s->h, wordblock);
 137             s->blkused = 0;
 138         }
 139         memcpy(s->block, q, len);
 140         s->blkused = len;
 141     }
 142 }
 143
 144 void SHA_Final(SHA_State * s, unsigned char *output)
 145 {
 146     int i;
 147     int pad;
 148     unsigned char c[64];
 149     uint32 lenhi, lenlo;
 150
 151     if (s->blkused >= 56)
 152         pad = 56 + 64 - s->blkused;
 153     else
 154         pad = 56 - s->blkused;
 155
 156     lenhi = (s->lenhi << 3) | (s->lenlo >> (32 - 3));
 157     lenlo = (s->lenlo << 3);
 158
 159     memset(c, 0, pad);
 160     c[0] = 0x80;
 161     SHA_Bytes(s, &c, pad);
 162
 163     c[0] = (lenhi >> 24) & 0xFF;
 164     c[1] = (lenhi >> 16) & 0xFF;
 165     c[2] = (lenhi >> 8) & 0xFF;
 166     c[3] = (lenhi >> 0) & 0xFF;
 167     c[4] = (lenlo >> 24) & 0xFF;
 168     c[5] = (lenlo >> 16) & 0xFF;
 169     c[6] = (lenlo >> 8) & 0xFF;
 170     c[7] = (lenlo >> 0) & 0xFF;
 171
 172     SHA_Bytes(s, &c, 8);
 173
 174     for (i = 0; i < 5; i++) {
 175         output[i * 4] = (s->h[i] >> 24) & 0xFF;
 176         output[i * 4 + 1] = (s->h[i] >> 16) & 0xFF;
 177         output[i * 4 + 2] = (s->h[i] >> 8) & 0xFF;
 178         output[i * 4 + 3] = (s->h[i]) & 0xFF;
 179     }
 180 }
 181
 182 void SHA_Simple(void *p, int len, unsigned char *output)
 183 {
 184     SHA_State s;
 185
 186     SHA_Init(&s);
 187     SHA_Bytes(&s, p, len);
 188     SHA_Final(&s, output);
 189 }
 190
 191 /*
 192  * Thin abstraction for things where hashes are pluggable.
 193  */
 194
 195 static void *sha1_init(void)
 196 {
 197     SHA_State *s;
 198
 199     s = snew(SHA_State);
 200     SHA_Init(s);
 201     return s;
 202 }
 203
 204 static void sha1_bytes(void *handle, void *p, int len)
 205 {
 206     SHA_State *s = handle;
 207
 208     SHA_Bytes(s, p, len);
 209 }
 210
 211 static void sha1_final(void *handle, unsigned char *output)
 212 {
 213     SHA_State *s = handle;
 214
 215     SHA_Final(s, output);
 216     sfree(s);
 217 }
 218
 219 const struct ssh_hash ssh_sha1 = {
 220     sha1_init, sha1_bytes, sha1_final, 20, "SHA-1"
 221 };
 222
 223 /* ----------------------------------------------------------------------
 224  * The above is the SHA-1 algorithm itself. Now we implement the
 225  * HMAC wrapper on it.
 226  */
 227
 228 static void *sha1_make_context(void)
 229 {
 230     return snewn(3, SHA_State);
 231 }
 232
 233 static void sha1_free_context(void *handle)
 234 {
 235     sfree(handle);
 236 }
 237
 238 static void sha1_key_internal(void *handle, unsigned char *key, int len)
 239 {
 240     SHA_State *keys = (SHA_State *)handle;
 241     unsigned char foo[64];
 242     int i;
 243
 244     memset(foo, 0x36, 64);
 245     for (i = 0; i < len && i < 64; i++)
 246         foo[i] ^= key[i];
 247     SHA_Init(&keys[0]);
 248     SHA_Bytes(&keys[0], foo, 64);
 249
 250     memset(foo, 0x5C, 64);
 251     for (i = 0; i < len && i < 64; i++)
 252         foo[i] ^= key[i];
 253     SHA_Init(&keys[1]);
 254     SHA_Bytes(&keys[1], foo, 64);
 255
 256     memset(foo, 0, 64);                /* burn the evidence */
 257 }
 258
 259 static void sha1_key(void *handle, unsigned char *key)
 260 {
 261     sha1_key_internal(handle, key, 20);
 262 }
 263
 264 static void sha1_key_buggy(void *handle, unsigned char *key)
 265 {
 266     sha1_key_internal(handle, key, 16);
 267 }
 268
 269 static void hmacsha1_start(void *handle)
 270 {
 271     SHA_State *keys = (SHA_State *)handle;
 272
 273     keys[2] = keys[0];                /* structure copy */
 274 }
 275
 276 static void hmacsha1_bytes(void *handle, unsigned char const *blk, int len)
 277 {
 278     SHA_State *keys = (SHA_State *)handle;
 279     SHA_Bytes(&keys[2], (void *)blk, len);
 280 }
 281
 282 static void hmacsha1_genresult(void *handle, unsigned char *hmac)
 283 {
 284     SHA_State *keys = (SHA_State *)handle;
 285     SHA_State s;
 286     unsigned char intermediate[20];
 287
 288     s = keys[2];                       /* structure copy */
 289     SHA_Final(&s, intermediate);
 290     s = keys[1];                       /* structure copy */
 291     SHA_Bytes(&s, intermediate, 20);
 292     SHA_Final(&s, hmac);
 293 }
 294
 295 static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
 296                          unsigned long seq, unsigned char *hmac)
 297 {
 298     unsigned char seqbuf[4];
 299
 300     seqbuf[0] = (unsigned char) ((seq >> 24) & 0xFF);
 301     seqbuf[1] = (unsigned char) ((seq >> 16) & 0xFF);
 302     seqbuf[2] = (unsigned char) ((seq >> 8) & 0xFF);
 303     seqbuf[3] = (unsigned char) ((seq) & 0xFF);
 304
 305     hmacsha1_start(handle);
 306     hmacsha1_bytes(handle, seqbuf, 4);
 307     hmacsha1_bytes(handle, blk, len);
 308     hmacsha1_genresult(handle, hmac);
 309 }
 310
 311 static void sha1_generate(void *handle, unsigned char *blk, int len,
 312                           unsigned long seq)
 313 {
 314     sha1_do_hmac(handle, blk, len, seq, blk + len);
 315 }
 316
 317 static int hmacsha1_verresult(void *handle, unsigned char const *hmac)
 318 {
 319     unsigned char correct[20];
 320     hmacsha1_genresult(handle, correct);
 321     return !memcmp(correct, hmac, 20);
 322 }
 323
 324 static int sha1_verify(void *handle, unsigned char *blk, int len,
 325                        unsigned long seq)
 326 {
 327     unsigned char correct[20];
 328     sha1_do_hmac(handle, blk, len, seq, correct);
 329     return !memcmp(correct, blk + len, 20);
 330 }
 331
 332 static void hmacsha1_96_genresult(void *handle, unsigned char *hmac)
 333 {
 334     unsigned char full[20];
 335     hmacsha1_genresult(handle, full);
 336     memcpy(hmac, full, 12);
 337 }
 338
 339 static void sha1_96_generate(void *handle, unsigned char *blk, int len,
 340                              unsigned long seq)
 341 {
 342     unsigned char full[20];
 343     sha1_do_hmac(handle, blk, len, seq, full);
 344     memcpy(blk + len, full, 12);
 345 }
 346
 347 static int hmacsha1_96_verresult(void *handle, unsigned char const *hmac)
 348 {
 349     unsigned char correct[20];
 350     hmacsha1_genresult(handle, correct);
 351     return !memcmp(correct, hmac, 12);
 352 }
 353
 354 static int sha1_96_verify(void *handle, unsigned char *blk, int len,
 355                        unsigned long seq)
 356 {
 357     unsigned char correct[20];
 358     sha1_do_hmac(handle, blk, len, seq, correct);
 359     return !memcmp(correct, blk + len, 12);
 360 }
 361
 362 void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
 363                       unsigned char *output) {
 364     SHA_State states[2];
 365     unsigned char intermediate[20];
 366
 367     sha1_key_internal(states, key, keylen);
 368     SHA_Bytes(&states[0], data, datalen);
 369     SHA_Final(&states[0], intermediate);
 370
 371     SHA_Bytes(&states[1], intermediate, 20);
 372     SHA_Final(&states[1], output);
 373 }
 374
 375 const struct ssh_mac ssh_hmac_sha1 = {
 376     sha1_make_context, sha1_free_context, sha1_key,
 377     sha1_generate, sha1_verify,
 378     hmacsha1_start, hmacsha1_bytes, hmacsha1_genresult, hmacsha1_verresult,
 379     "hmac-sha1",
 380     20,
 381     "HMAC-SHA1"
 382 };
 383
 384 const struct ssh_mac ssh_hmac_sha1_96 = {
 385     sha1_make_context, sha1_free_context, sha1_key,
 386     sha1_96_generate, sha1_96_verify,
 387     hmacsha1_start, hmacsha1_bytes,
 388     hmacsha1_96_genresult, hmacsha1_96_verresult,
 389     "hmac-sha1-96",
 390     12,
 391     "HMAC-SHA1-96"
 392 };
 393
 394 const struct ssh_mac ssh_hmac_sha1_buggy = {
 395     sha1_make_context, sha1_free_context, sha1_key_buggy,
 396     sha1_generate, sha1_verify,
 397     hmacsha1_start, hmacsha1_bytes, hmacsha1_genresult, hmacsha1_verresult,
 398     "hmac-sha1",
 399     20,
 400     "bug-compatible HMAC-SHA1"
 401 };
 402
 403 const struct ssh_mac ssh_hmac_sha1_96_buggy = {
 404     sha1_make_context, sha1_free_context, sha1_key_buggy,
 405     sha1_96_generate, sha1_96_verify,
 406     hmacsha1_start, hmacsha1_bytes,
 407     hmacsha1_96_genresult, hmacsha1_96_verresult,
 408     "hmac-sha1-96",
 409     12,
 410     "bug-compatible HMAC-SHA1-96"
 411 };