lib/hcrypto/rsa-tfm.c

   1 /*
   2  * Copyright (c) 2006 - 2007, 2010 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <config.h>
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <krb5-types.h>
  39 #include <assert.h>
  40
  41 #include <rsa.h>
  42
  43 #include <roken.h>
  44
  45 #include "tfm.h"
  46
  47 static void
  48 BN2mpz(fp_int *s, const BIGNUM *bn)
  49 {
  50     size_t len;
  51     void *p;
  52
  53     fp_init(s);
  54
  55     len = BN_num_bytes(bn);
  56     p = malloc(len);
  57     BN_bn2bin(bn, p);
  58     fp_read_unsigned_bin(s, p, len);
  59     free(p);
  60 }
  61
  62 static int
  63 tfm_rsa_private_calculate(fp_int * in, fp_int * p,  fp_int * q,
  64                           fp_int * dmp1, fp_int * dmq1, fp_int * iqmp,
  65                           fp_int * out)
  66 {
  67     fp_int vp, vq, u;
  68
  69     fp_init_multi(&vp, &vq, &u, NULL);
  70
  71     /* vq = c ^ (d mod (q - 1)) mod q */
  72     /* vp = c ^ (d mod (p - 1)) mod p */
  73     fp_mod(in, p, &u);
  74     fp_exptmod(&u, dmp1, p, &vp);
  75     fp_mod(in, q, &u);
  76     fp_exptmod(&u, dmq1, q, &vq);
  77
  78     /* C2 = 1/q mod p  (iqmp) */
  79     /* u = (vp - vq)C2 mod p. */
  80     fp_sub(&vp, &vq, &u);
  81     if (u.sign == FP_NEG)
  82         fp_add(&u, p, &u);
  83     fp_mul(&u, iqmp, &u);
  84     fp_mod(&u, p, &u);
  85
  86     /* c ^ d mod n = vq + u q */
  87     fp_mul(&u, q, &u);
  88     fp_add(&u, &vq, out);
  89
  90     fp_zero(&vp);
  91     fp_zero(&vq);
  92     fp_zero(&u);
  93
  94     return 0;
  95 }
  96
  97 /*
  98  *
  99  */
 100
 101 static int
 102 tfm_rsa_public_encrypt(int flen, const unsigned char* from,
 103                         unsigned char* to, RSA* rsa, int padding)
 104 {
 105     unsigned char *p, *p0;
 106     int res;
 107     size_t size, padlen;
 108     fp_int enc, dec, n, e;
 109
 110     if (padding != RSA_PKCS1_PADDING)
 111         return -1;
 112
 113     size = RSA_size(rsa);
 114
 115     if (size < RSA_PKCS1_PADDING_SIZE || size - RSA_PKCS1_PADDING_SIZE < flen)
 116         return -2;
 117
 118     BN2mpz(&n, rsa->n);
 119     BN2mpz(&e, rsa->e);
 120
 121     p = p0 = malloc(size - 1);
 122     if (p0 == NULL) {
 123         fp_zero(&e);
 124         fp_zero(&n);
 125         return -3;
 126     }
 127
 128     padlen = size - flen - 3;
 129
 130     *p++ = 2;
 131     if (RAND_bytes(p, padlen) != 1) {
 132         fp_zero(&e);
 133         fp_zero(&n);
 134         free(p0);
 135         return -4;
 136     }
 137     while(padlen) {
 138         if (*p == 0)
 139             *p = 1;
 140         padlen--;
 141         p++;
 142     }
 143     *p++ = 0;
 144     memcpy(p, from, flen);
 145     p += flen;
 146     assert((p - p0) == size - 1);
 147
 148     fp_init_multi(&enc, &dec, NULL);
 149     fp_read_unsigned_bin(&dec, p0, size - 1);
 150     free(p0);
 151
 152     res = fp_exptmod(&dec, &e, &n, &enc);
 153
 154     fp_zero(&dec);
 155     fp_zero(&e);
 156     fp_zero(&n);
 157
 158     if (res != 0)
 159         return -4;
 160
 161     {
 162         size_t ssize;
 163         ssize = fp_unsigned_bin_size(&enc);
 164         assert(size >= ssize);
 165         fp_to_unsigned_bin(&enc, to);
 166         size = ssize;
 167     }
 168     fp_zero(&enc);
 169
 170     return size;
 171 }
 172
 173 static int
 174 tfm_rsa_public_decrypt(int flen, const unsigned char* from,
 175                        unsigned char* to, RSA* rsa, int padding)
 176 {
 177     unsigned char *p;
 178     int res;
 179     size_t size;
 180     fp_int s, us, n, e;
 181
 182     if (padding != RSA_PKCS1_PADDING)
 183         return -1;
 184
 185     if (flen > RSA_size(rsa))
 186         return -2;
 187
 188     BN2mpz(&n, rsa->n);
 189     BN2mpz(&e, rsa->e);
 190
 191 #if 0
 192     /* Check that the exponent is larger then 3 */
 193     if (mp_int_compare_value(&e, 3) <= 0) {
 194         fp_zero(&n);
 195         fp_zero(&e);
 196         return -3;
 197     }
 198 #endif
 199
 200     fp_init_multi(&s, &us, NULL);
 201     fp_read_unsigned_bin(&s, rk_UNCONST(from), flen);
 202
 203     if (fp_cmp(&s, &n) >= 0) {
 204         fp_zero(&n);
 205         fp_zero(&e);
 206         return -4;
 207     }
 208
 209     res = fp_exptmod(&s, &e, &n, &us);
 210
 211     fp_zero(&s);
 212     fp_zero(&n);
 213     fp_zero(&e);
 214
 215     if (res != 0)
 216         return -5;
 217     p = to;
 218
 219
 220     size = fp_unsigned_bin_size(&us);
 221     assert(size <= RSA_size(rsa));
 222     fp_to_unsigned_bin(&us, p);
 223
 224     fp_zero(&us);
 225
 226     /* head zero was skipped by fp_to_unsigned_bin */
 227     if (*p == 0)
 228         return -6;
 229     if (*p != 1)
 230         return -7;
 231     size--; p++;
 232     while (size && *p == 0xff) {
 233         size--; p++;
 234     }
 235     if (size == 0 || *p != 0)
 236         return -8;
 237     size--; p++;
 238
 239     memmove(to, p, size);
 240
 241     return size;
 242 }
 243
 244 static int
 245 tfm_rsa_private_encrypt(int flen, const unsigned char* from,
 246                         unsigned char* to, RSA* rsa, int padding)
 247 {
 248     unsigned char *p, *p0;
 249     int res;
 250     int size;
 251     fp_int in, out, n, e;
 252
 253     if (padding != RSA_PKCS1_PADDING)
 254         return -1;
 255
 256     size = RSA_size(rsa);
 257
 258     if (size < RSA_PKCS1_PADDING_SIZE || size - RSA_PKCS1_PADDING_SIZE < flen)
 259         return -2;
 260
 261     p0 = p = malloc(size);
 262     *p++ = 0;
 263     *p++ = 1;
 264     memset(p, 0xff, size - flen - 3);
 265     p += size - flen - 3;
 266     *p++ = 0;
 267     memcpy(p, from, flen);
 268     p += flen;
 269     assert((p - p0) == size);
 270
 271     BN2mpz(&n, rsa->n);
 272     BN2mpz(&e, rsa->e);
 273
 274     fp_init_multi(&in, &out, NULL);
 275     fp_read_unsigned_bin(&in, p0, size);
 276     free(p0);
 277
 278     if(in.sign == FP_NEG ||
 279        fp_cmp(&in, &n) >= 0) {
 280         size = -3;
 281         goto out;
 282     }
 283
 284     if (rsa->p && rsa->q && rsa->dmp1 && rsa->dmq1 && rsa->iqmp) {
 285         fp_int p, q, dmp1, dmq1, iqmp;
 286
 287         BN2mpz(&p, rsa->p);
 288         BN2mpz(&q, rsa->q);
 289         BN2mpz(&dmp1, rsa->dmp1);
 290         BN2mpz(&dmq1, rsa->dmq1);
 291         BN2mpz(&iqmp, rsa->iqmp);
 292
 293         res = tfm_rsa_private_calculate(&in, &p, &q, &dmp1, &dmq1, &iqmp, &out);
 294
 295         fp_zero(&p);
 296         fp_zero(&q);
 297         fp_zero(&dmp1);
 298         fp_zero(&dmq1);
 299         fp_zero(&iqmp);
 300
 301         if (res != 0) {
 302             size = -4;
 303             goto out;
 304         }
 305     } else {
 306         fp_int d;
 307
 308         BN2mpz(&d, rsa->d);
 309         res = fp_exptmod(&in, &d, &n, &out);
 310         fp_zero(&d);
 311         if (res != 0) {
 312             size = -5;
 313             goto out;
 314         }
 315     }
 316
 317     if (size > 0) {
 318         size_t ssize;
 319         ssize = fp_unsigned_bin_size(&out);
 320         assert(size >= ssize);
 321         fp_to_unsigned_bin(&out, to);
 322         size = ssize;
 323     }
 324
 325  out:
 326     fp_zero(&e);
 327     fp_zero(&n);
 328     fp_zero(&in);
 329     fp_zero(&out);
 330
 331     return size;
 332 }
 333
 334 static int
 335 tfm_rsa_private_decrypt(int flen, const unsigned char* from,
 336                         unsigned char* to, RSA* rsa, int padding)
 337 {
 338     unsigned char *ptr;
 339     int res;
 340     size_t size;
 341     fp_int in, out, n, e;
 342
 343     if (padding != RSA_PKCS1_PADDING)
 344         return -1;
 345
 346     size = RSA_size(rsa);
 347     if (flen > size)
 348         return -2;
 349
 350     fp_init_multi(&in, &out, NULL);
 351
 352     BN2mpz(&n, rsa->n);
 353     BN2mpz(&e, rsa->e);
 354
 355     fp_read_unsigned_bin(&in, rk_UNCONST(from), flen);
 356
 357     if(in.sign == FP_NEG ||
 358        fp_cmp(&in, &n) >= 0) {
 359         size = -2;
 360         goto out;
 361     }
 362
 363     if (rsa->p && rsa->q && rsa->dmp1 && rsa->dmq1 && rsa->iqmp) {
 364         fp_int p, q, dmp1, dmq1, iqmp;
 365
 366         BN2mpz(&p, rsa->p);
 367         BN2mpz(&q, rsa->q);
 368         BN2mpz(&dmp1, rsa->dmp1);
 369         BN2mpz(&dmq1, rsa->dmq1);
 370         BN2mpz(&iqmp, rsa->iqmp);
 371
 372         res = tfm_rsa_private_calculate(&in, &p, &q, &dmp1, &dmq1, &iqmp, &out);
 373
 374         fp_zero(&p);
 375         fp_zero(&q);
 376         fp_zero(&dmp1);
 377         fp_zero(&dmq1);
 378         fp_zero(&iqmp);
 379
 380         if (res != 0) {
 381             size = -3;
 382             goto out;
 383         }
 384
 385     } else {
 386         fp_int d;
 387
 388         if(in.sign == FP_NEG ||
 389            fp_cmp(&in, &n) >= 0)
 390             return -4;
 391
 392         BN2mpz(&d, rsa->d);
 393         res = fp_exptmod(&in, &d, &n, &out);
 394         fp_zero(&d);
 395         if (res != 0) {
 396             size = -5;
 397             goto out;
 398         }
 399     }
 400
 401     ptr = to;
 402     {
 403         size_t ssize;
 404         ssize = fp_unsigned_bin_size(&out);
 405         assert(size >= ssize);
 406         fp_to_unsigned_bin(&out, ptr);
 407         size = ssize;
 408     }
 409
 410     /* head zero was skipped by mp_int_to_unsigned */
 411     if (*ptr != 2) {
 412         size = -6;
 413         goto out;
 414     }
 415     size--; ptr++;
 416     while (size && *ptr != 0) {
 417         size--; ptr++;
 418     }
 419     if (size == 0)
 420         return -7;
 421     size--; ptr++;
 422
 423     memmove(to, ptr, size);
 424
 425  out:
 426     fp_zero(&e);
 427     fp_zero(&n);
 428     fp_zero(&in);
 429     fp_zero(&out);
 430
 431     return size;
 432 }
 433
 434 static BIGNUM *
 435 mpz2BN(fp_int *s)
 436 {
 437     size_t size;
 438     BIGNUM *bn;
 439     void *p;
 440
 441     size = fp_unsigned_bin_size(s);
 442     p = malloc(size);
 443     if (p == NULL && size != 0)
 444         return NULL;
 445
 446     fp_to_unsigned_bin(s, p);
 447
 448     bn = BN_bin2bn(p, size, NULL);
 449     free(p);
 450     return bn;
 451 }
 452
 453 static int
 454 random_num(fp_int *num, size_t len)
 455 {
 456     unsigned char *p;
 457
 458     len = (len + 7) / 8;
 459     p = malloc(len);
 460     if (p == NULL)
 461         return 1;
 462     if (RAND_bytes(p, len) != 1) {
 463         free(p);
 464         return 1;
 465     }
 466     fp_read_unsigned_bin(num, p, len);
 467     free(p);
 468     return 0;
 469 }
 470
 471 #define CHECK(f, v) if ((f) != (v)) { goto out; }
 472
 473 static int
 474 tfm_rsa_generate_key(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb)
 475 {
 476     fp_int el, p, q, n, d, dmp1, dmq1, iqmp, t1, t2, t3;
 477     int counter, ret, bitsp;
 478
 479     if (bits < 789)
 480         return -1;
 481
 482     bitsp = (bits + 1) / 2;
 483
 484     ret = -1;
 485
 486     fp_init_multi(&el, &p, &q, &n, &n, &d, &dmp1, &dmq1, &iqmp, &t1, &t2, &t3, NULL);
 487
 488     BN2mpz(&el, e);
 489
 490     /* generate p and q so that p != q and bits(pq) ~ bits */
 491     counter = 0;
 492     do {
 493         BN_GENCB_call(cb, 2, counter++);
 494         CHECK(random_num(&p, bitsp), 0);
 495         CHECK(fp_find_prime(&p), FP_YES);
 496
 497         fp_sub_d(&p, 1, &t1);
 498         fp_gcd(&t1, &el, &t2);
 499     } while(fp_cmp_d(&t2, 1) != 0);
 500
 501     BN_GENCB_call(cb, 3, 0);
 502
 503     counter = 0;
 504     do {
 505         BN_GENCB_call(cb, 2, counter++);
 506         CHECK(random_num(&q, bits - bitsp), 0);
 507         CHECK(fp_find_prime(&q), FP_YES);
 508
 509         if (fp_cmp(&p, &q) == 0) /* don't let p and q be the same */
 510             continue;
 511
 512         fp_sub_d(&q, 1, &t1);
 513         fp_gcd(&t1, &el, &t2);
 514     } while(fp_cmp_d(&t2, 1) != 0);
 515
 516     /* make p > q */
 517     if (fp_cmp(&p, &q) < 0) {
 518         fp_int c;
 519         fp_copy(&p, &c);
 520         fp_copy(&q, &p);
 521         fp_copy(&c, &q);
 522     }
 523
 524     BN_GENCB_call(cb, 3, 1);
 525
 526     /* calculate n,             n = p * q */
 527     fp_mul(&p, &q, &n);
 528
 529     /* calculate d,             d = 1/e mod (p - 1)(q - 1) */
 530     fp_sub_d(&p, 1, &t1);
 531     fp_sub_d(&q, 1, &t2);
 532     fp_mul(&t1, &t2, &t3);
 533     fp_invmod(&el, &t3, &d);
 534
 535     /* calculate dmp1           dmp1 = d mod (p-1) */
 536     fp_mod(&d, &t1, &dmp1);
 537     /* calculate dmq1           dmq1 = d mod (q-1) */
 538     fp_mod(&d, &t2, &dmq1);
 539     /* calculate iqmp           iqmp = 1/q mod p */
 540     fp_invmod(&q, &p, &iqmp);
 541
 542     /* fill in RSA key */
 543
 544     rsa->e = mpz2BN(&el);
 545     rsa->p = mpz2BN(&p);
 546     rsa->q = mpz2BN(&q);
 547     rsa->n = mpz2BN(&n);
 548     rsa->d = mpz2BN(&d);
 549     rsa->dmp1 = mpz2BN(&dmp1);
 550     rsa->dmq1 = mpz2BN(&dmq1);
 551     rsa->iqmp = mpz2BN(&iqmp);
 552
 553     ret = 1;
 554
 555 out:
 556     fp_zero(&el);
 557     fp_zero(&p);
 558     fp_zero(&q);
 559     fp_zero(&n);
 560     fp_zero(&d);
 561     fp_zero(&dmp1);
 562     fp_zero(&dmq1);
 563     fp_zero(&iqmp);
 564     fp_zero(&t1);
 565     fp_zero(&t2);
 566     fp_zero(&t3);
 567
 568     return ret;
 569 }
 570
 571 static int
 572 tfm_rsa_init(RSA *rsa)
 573 {
 574     return 1;
 575 }
 576
 577 static int
 578 tfm_rsa_finish(RSA *rsa)
 579 {
 580     return 1;
 581 }
 582
 583 const RSA_METHOD hc_rsa_tfm_method = {
 584     "hcrypto tfm RSA",
 585     tfm_rsa_public_encrypt,
 586     tfm_rsa_public_decrypt,
 587     tfm_rsa_private_encrypt,
 588     tfm_rsa_private_decrypt,
 589     NULL,
 590     NULL,
 591     tfm_rsa_init,
 592     tfm_rsa_finish,
 593     0,
 594     NULL,
 595     NULL,
 596     NULL,
 597     tfm_rsa_generate_key
 598 };
 599
 600 const RSA_METHOD *
 601 RSA_tfm_method(void)
 602 {
 603     return &hc_rsa_tfm_method;
 604 }