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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.com |
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10 */ |
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11 #include "tomcrypt.h" |
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12 |
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13 /** |
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14 @file katja_make_key.c |
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15 Katja key generation, Tom St Denis |
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16 */ |
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17 |
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18 #ifdef MKAT |
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19 |
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20 /** |
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21 Create a Katja key |
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22 @param prng An active PRNG state |
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23 @param wprng The index of the PRNG desired |
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24 @param size The size of the modulus (key size) desired (octets) |
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25 @param key [out] Destination of a newly created private key pair |
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26 @return CRYPT_OK if successful, upon error all allocated ram is freed |
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27 */ |
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28 int katja_make_key(prng_state *prng, int wprng, int size, katja_key *key) |
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29 { |
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30 void *p, *q, *tmp1, *tmp2; |
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31 int err; |
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32 |
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33 LTC_ARGCHK(key != NULL); |
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34 LTC_ARGCHK(ltc_mp.name != NULL); |
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35 |
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36 if ((size < (MIN_KAT_SIZE/8)) || (size > (MAX_KAT_SIZE/8))) { |
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37 return CRYPT_INVALID_KEYSIZE; |
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38 } |
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39 |
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40 if ((err = prng_is_valid(wprng)) != CRYPT_OK) { |
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41 return err; |
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42 } |
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43 |
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44 if ((err = mp_init_multi(&p, &q, &tmp1, &tmp2, NULL)) != CRYPT_OK) { |
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45 return err; |
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46 } |
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47 |
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48 /* divide size by three */ |
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49 size = (((size << 3) / 3) + 7) >> 3; |
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50 |
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51 /* make prime "q" (we negate size to make q == 3 mod 4) */ |
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52 if ((err = rand_prime(q, -size, prng, wprng)) != CRYPT_OK) { goto done; } |
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53 if ((err = mp_sub_d(q, 1, tmp1)) != CRYPT_OK) { goto done; } |
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54 |
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55 /* make prime "p" */ |
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56 do { |
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57 if ((err = rand_prime(p, size+1, prng, wprng)) != CRYPT_OK) { goto done; } |
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58 if ((err = mp_gcd(p, tmp1, tmp2)) != CRYPT_OK) { goto done; } |
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59 } while (mp_cmp_d(tmp2, 1) != LTC_MP_EQ); |
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60 |
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61 /* make key */ |
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62 if ((err = mp_init_multi(&key->d, &key->N, &key->dQ, &key->dP, |
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63 &key->qP, &key->p, &key->q, &key->pq, NULL)) != CRYPT_OK) { |
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64 goto error; |
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65 } |
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66 |
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67 /* n=p^2q and 1/n mod pq */ |
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68 if ((err = mp_copy( p, key->p)) != CRYPT_OK) { goto error2; } |
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69 if ((err = mp_copy( q, key->q)) != CRYPT_OK) { goto error2; } |
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70 if ((err = mp_mul(key->p, key->q, key->pq)) != CRYPT_OK) { goto error2; } /* tmp1 = pq */ |
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71 if ((err = mp_mul(key->pq, key->p, key->N)) != CRYPT_OK) { goto error2; } /* N = p^2q */ |
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72 if ((err = mp_sub_d( p, 1, tmp1)) != CRYPT_OK) { goto error2; } /* tmp1 = q-1 */ |
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73 if ((err = mp_sub_d( q, 1, tmp2)) != CRYPT_OK) { goto error2; } /* tmp2 = p-1 */ |
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74 if ((err = mp_lcm(tmp1, tmp2, key->d)) != CRYPT_OK) { goto error2; } /* tmp1 = lcd(p-1,q-1) */ |
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75 if ((err = mp_invmod( key->N, key->d, key->d)) != CRYPT_OK) { goto error2; } /* key->d = 1/N mod pq */ |
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76 |
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77 /* optimize for CRT now */ |
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78 /* find d mod q-1 and d mod p-1 */ |
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79 if ((err = mp_mod( key->d, tmp1, key->dP)) != CRYPT_OK) { goto error2; } /* dP = d mod p-1 */ |
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80 if ((err = mp_mod( key->d, tmp2, key->dQ)) != CRYPT_OK) { goto error2; } /* dQ = d mod q-1 */ |
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81 if ((err = mp_invmod( q, p, key->qP)) != CRYPT_OK) { goto error2; } /* qP = 1/q mod p */ |
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82 |
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83 /* set key type (in this case it's CRT optimized) */ |
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84 key->type = PK_PRIVATE; |
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85 |
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86 /* return ok and free temps */ |
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87 err = CRYPT_OK; |
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88 goto done; |
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89 error2: |
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90 mp_clear_multi( key->d, key->N, key->dQ, key->dP, key->qP, key->p, key->q, key->pq, NULL); |
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91 error: |
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92 done: |
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93 mp_clear_multi( tmp2, tmp1, p, q, NULL); |
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94 return err; |
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95 } |
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96 |
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97 #endif |
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98 |
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99 /* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_make_key.c,v $ */ |
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100 /* $Revision: 1.10 $ */ |
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101 /* $Date: 2006/03/31 14:15:35 $ */ |
