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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 |
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12 /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b |
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13 * |
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14 * All curves taken from NIST recommendation paper of July 1999 |
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15 * Available at http://csrc.nist.gov/cryptval/dss.htm |
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16 */ |
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17 #include "tomcrypt.h" |
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18 |
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19 /** |
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20 @file ecc_import.c |
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21 ECC Crypto, Tom St Denis |
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22 */ |
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23 |
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24 #ifdef MECC |
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25 |
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26 static int is_point(ecc_key *key) |
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27 { |
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28 void *prime, *b, *t1, *t2; |
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29 int err; |
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30 |
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31 if ((err = mp_init_multi(&prime, &b, &t1, &t2, NULL)) != CRYPT_OK) { |
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32 return err; |
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33 } |
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34 |
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35 /* load prime and b */ |
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36 if ((err = mp_read_radix(prime, key->dp->prime, 16)) != CRYPT_OK) { goto error; } |
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37 if ((err = mp_read_radix(b, key->dp->B, 16)) != CRYPT_OK) { goto error; } |
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38 |
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39 /* compute y^2 */ |
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40 if ((err = mp_sqr(key->pubkey.y, t1)) != CRYPT_OK) { goto error; } |
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41 |
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42 /* compute x^3 */ |
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43 if ((err = mp_sqr(key->pubkey.x, t2)) != CRYPT_OK) { goto error; } |
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44 if ((err = mp_mod(t2, prime, t2)) != CRYPT_OK) { goto error; } |
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45 if ((err = mp_mul(key->pubkey.x, t2, t2)) != CRYPT_OK) { goto error; } |
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46 |
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47 /* compute y^2 - x^3 */ |
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48 if ((err = mp_sub(t1, t2, t1)) != CRYPT_OK) { goto error; } |
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49 |
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50 /* compute y^2 - x^3 + 3x */ |
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51 if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } |
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52 if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } |
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53 if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } |
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54 if ((err = mp_mod(t1, prime, t1)) != CRYPT_OK) { goto error; } |
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55 while (mp_cmp_d(t1, 0) == LTC_MP_LT) { |
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56 if ((err = mp_add(t1, prime, t1)) != CRYPT_OK) { goto error; } |
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57 } |
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58 while (mp_cmp(t1, prime) != LTC_MP_LT) { |
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59 if ((err = mp_sub(t1, prime, t1)) != CRYPT_OK) { goto error; } |
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60 } |
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61 |
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62 /* compare to b */ |
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63 if (mp_cmp(t1, b) != LTC_MP_EQ) { |
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64 err = CRYPT_INVALID_PACKET; |
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65 } else { |
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66 err = CRYPT_OK; |
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67 } |
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68 |
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69 error: |
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70 mp_clear_multi(prime, b, t1, t2, NULL); |
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71 return err; |
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72 } |
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73 |
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74 /** |
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75 Import an ECC key from a binary packet |
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76 @param in The packet to import |
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77 @param inlen The length of the packet |
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78 @param key [out] The destination of the import |
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79 @return CRYPT_OK if successful, upon error all allocated memory will be freed |
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80 */ |
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81 int ecc_import(const unsigned char *in, unsigned long inlen, ecc_key *key) |
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82 { |
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83 return ecc_import_ex(in, inlen, key, NULL); |
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84 } |
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85 |
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86 /** |
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87 Import an ECC key from a binary packet, using user supplied domain params rather than one of the NIST ones |
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88 @param in The packet to import |
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89 @param inlen The length of the packet |
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90 @param key [out] The destination of the import |
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91 @param dp pointer to user supplied params; must be the same as the params used when exporting |
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92 @return CRYPT_OK if successful, upon error all allocated memory will be freed |
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93 */ |
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94 int ecc_import_ex(const unsigned char *in, unsigned long inlen, ecc_key *key, const ltc_ecc_set_type *dp) |
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95 { |
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96 unsigned long key_size; |
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97 unsigned char flags[1]; |
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98 int err; |
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99 |
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100 LTC_ARGCHK(in != NULL); |
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101 LTC_ARGCHK(key != NULL); |
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102 LTC_ARGCHK(ltc_mp.name != NULL); |
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103 |
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104 /* init key */ |
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105 if (mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL) != CRYPT_OK) { |
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106 return CRYPT_MEM; |
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107 } |
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108 |
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109 /* find out what type of key it is */ |
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110 if ((err = der_decode_sequence_multi(in, inlen, |
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111 LTC_ASN1_BIT_STRING, 1UL, &flags, |
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112 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { |
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113 goto done; |
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114 } |
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115 |
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116 |
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117 if (flags[0] == 1) { |
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118 /* private key */ |
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119 key->type = PK_PRIVATE; |
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120 if ((err = der_decode_sequence_multi(in, inlen, |
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121 LTC_ASN1_BIT_STRING, 1UL, flags, |
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122 LTC_ASN1_SHORT_INTEGER, 1UL, &key_size, |
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123 LTC_ASN1_INTEGER, 1UL, key->pubkey.x, |
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124 LTC_ASN1_INTEGER, 1UL, key->pubkey.y, |
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125 LTC_ASN1_INTEGER, 1UL, key->k, |
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126 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { |
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127 goto done; |
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128 } |
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129 } else { |
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130 /* public key */ |
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131 key->type = PK_PUBLIC; |
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132 if ((err = der_decode_sequence_multi(in, inlen, |
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133 LTC_ASN1_BIT_STRING, 1UL, flags, |
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134 LTC_ASN1_SHORT_INTEGER, 1UL, &key_size, |
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135 LTC_ASN1_INTEGER, 1UL, key->pubkey.x, |
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136 LTC_ASN1_INTEGER, 1UL, key->pubkey.y, |
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137 LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { |
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138 goto done; |
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139 } |
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140 } |
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141 |
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142 if (dp == NULL) { |
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143 /* find the idx */ |
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144 for (key->idx = 0; ltc_ecc_sets[key->idx].size && (unsigned long)ltc_ecc_sets[key->idx].size != key_size; ++key->idx); |
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145 if (ltc_ecc_sets[key->idx].size == 0) { |
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146 err = CRYPT_INVALID_PACKET; |
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147 goto done; |
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148 } |
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149 key->dp = <c_ecc_sets[key->idx]; |
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150 } else { |
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151 key->idx = -1; |
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152 key->dp = dp; |
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153 } |
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154 /* set z */ |
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155 if ((err = mp_set(key->pubkey.z, 1)) != CRYPT_OK) { goto done; } |
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156 |
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157 /* is it a point on the curve? */ |
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158 if ((err = is_point(key)) != CRYPT_OK) { |
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159 goto done; |
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160 } |
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161 |
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162 /* we're good */ |
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163 return CRYPT_OK; |
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164 done: |
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165 mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL); |
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166 return err; |
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167 } |
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168 #endif |
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169 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_import.c,v $ */ |
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170 /* $Revision: 1.11 $ */ |
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171 /* $Date: 2006/12/04 02:19:48 $ */ |
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172 |
