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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
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2 * |
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3 * LibTomCrypt is a library that provides various cryptographic |
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4 * algorithms in a highly modular and flexible manner. |
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5 * |
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6 * The library is free for all purposes without any express |
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7 * guarantee it works. |
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8 * |
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9 * Tom St Denis, [email protected], http://libtomcrypt.org |
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10 */ |
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11 |
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12 /* RSA Code by Tom St Denis */ |
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13 #include "mycrypt.h" |
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14 |
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15 #ifdef MRSA |
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16 |
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17 int rsa_make_key(prng_state *prng, int wprng, int size, long e, rsa_key *key) |
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18 { |
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19 mp_int p, q, tmp1, tmp2, tmp3; |
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15
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20 int err; |
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21 |
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22 _ARGCHK(key != NULL); |
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23 |
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24 if ((size < (MIN_RSA_SIZE/8)) || (size > (MAX_RSA_SIZE/8))) { |
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25 return CRYPT_INVALID_KEYSIZE; |
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26 } |
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27 |
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28 if ((e < 3) || ((e & 1) == 0)) { |
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29 return CRYPT_INVALID_ARG; |
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30 } |
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31 |
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32 if ((err = prng_is_valid(wprng)) != CRYPT_OK) { |
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33 return err; |
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34 } |
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35 |
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36 if ((err = mp_init_multi(&p, &q, &tmp1, &tmp2, &tmp3, NULL)) != MP_OKAY) { |
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37 return mpi_to_ltc_error(err); |
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38 } |
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39 |
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40 /* make primes p and q (optimization provided by Wayne Scott) */ |
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41 if ((err = mp_set_int(&tmp3, e)) != MP_OKAY) { goto error; } /* tmp3 = e */ |
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42 |
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43 /* make prime "p" */ |
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44 do { |
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45 if ((err = rand_prime(&p, size*4, prng, wprng)) != CRYPT_OK) { goto done; } |
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46 if ((err = mp_sub_d(&p, 1, &tmp1)) != MP_OKAY) { goto error; } /* tmp1 = p-1 */ |
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47 if ((err = mp_gcd(&tmp1, &tmp3, &tmp2)) != MP_OKAY) { goto error; } /* tmp2 = gcd(p-1, e) */ |
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48 } while (mp_cmp_d(&tmp2, 1) != 0); /* while e divides p-1 */ |
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49 |
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50 /* make prime "q" */ |
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51 do { |
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52 if ((err = rand_prime(&q, size*4, prng, wprng)) != CRYPT_OK) { goto done; } |
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53 if ((err = mp_sub_d(&q, 1, &tmp1)) != MP_OKAY) { goto error; } /* tmp1 = q-1 */ |
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54 if ((err = mp_gcd(&tmp1, &tmp3, &tmp2)) != MP_OKAY) { goto error; } /* tmp2 = gcd(q-1, e) */ |
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55 } while (mp_cmp_d(&tmp2, 1) != 0); /* while e divides q-1 */ |
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56 |
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57 /* tmp1 = lcm(p-1, q-1) */ |
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58 if ((err = mp_sub_d(&p, 1, &tmp2)) != MP_OKAY) { goto error; } /* tmp2 = p-1 */ |
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59 /* tmp1 = q-1 (previous do/while loop) */ |
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60 if ((err = mp_lcm(&tmp1, &tmp2, &tmp1)) != MP_OKAY) { goto error; } /* tmp1 = lcm(p-1, q-1) */ |
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61 |
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62 /* make key */ |
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63 if ((err = mp_init_multi(&key->e, &key->d, &key->N, &key->dQ, &key->dP, |
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143
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64 &key->qP, &key->p, &key->q, NULL)) != MP_OKAY) { |
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65 goto error; |
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66 } |
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67 |
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68 if ((err = mp_set_int(&key->e, e)) != MP_OKAY) { goto error2; } /* key->e = e */ |
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69 if ((err = mp_invmod(&key->e, &tmp1, &key->d)) != MP_OKAY) { goto error2; } /* key->d = 1/e mod lcm(p-1,q-1) */ |
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70 if ((err = mp_mul(&p, &q, &key->N)) != MP_OKAY) { goto error2; } /* key->N = pq */ |
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71 |
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72 /* optimize for CRT now */ |
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73 /* find d mod q-1 and d mod p-1 */ |
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74 if ((err = mp_sub_d(&p, 1, &tmp1)) != MP_OKAY) { goto error2; } /* tmp1 = q-1 */ |
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75 if ((err = mp_sub_d(&q, 1, &tmp2)) != MP_OKAY) { goto error2; } /* tmp2 = p-1 */ |
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76 if ((err = mp_mod(&key->d, &tmp1, &key->dP)) != MP_OKAY) { goto error2; } /* dP = d mod p-1 */ |
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77 if ((err = mp_mod(&key->d, &tmp2, &key->dQ)) != MP_OKAY) { goto error2; } /* dQ = d mod q-1 */ |
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78 if ((err = mp_invmod(&q, &p, &key->qP)) != MP_OKAY) { goto error2; } /* qP = 1/q mod p */ |
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79 |
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80 if ((err = mp_copy(&p, &key->p)) != MP_OKAY) { goto error2; } |
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81 if ((err = mp_copy(&q, &key->q)) != MP_OKAY) { goto error2; } |
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82 |
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83 /* shrink ram required */ |
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84 if ((err = mp_shrink(&key->e)) != MP_OKAY) { goto error2; } |
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85 if ((err = mp_shrink(&key->d)) != MP_OKAY) { goto error2; } |
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86 if ((err = mp_shrink(&key->N)) != MP_OKAY) { goto error2; } |
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87 if ((err = mp_shrink(&key->dQ)) != MP_OKAY) { goto error2; } |
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88 if ((err = mp_shrink(&key->dP)) != MP_OKAY) { goto error2; } |
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89 if ((err = mp_shrink(&key->qP)) != MP_OKAY) { goto error2; } |
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90 if ((err = mp_shrink(&key->p)) != MP_OKAY) { goto error2; } |
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91 if ((err = mp_shrink(&key->q)) != MP_OKAY) { goto error2; } |
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92 |
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93 /* set key type (in this case it's CRT optimized) */ |
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94 key->type = PK_PRIVATE; |
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95 |
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96 /* return ok and free temps */ |
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97 err = CRYPT_OK; |
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98 goto done; |
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99 error2: |
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100 mp_clear_multi(&key->d, &key->e, &key->N, &key->dQ, &key->dP, |
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101 &key->qP, &key->p, &key->q, NULL); |
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102 error: |
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103 err = mpi_to_ltc_error(err); |
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104 done: |
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105 mp_clear_multi(&tmp3, &tmp2, &tmp1, &p, &q, NULL); |
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106 return err; |
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107 } |
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108 |
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109 #endif |
