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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_encrypt_key.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 /** |
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27 Encrypt a symmetric key with ECC |
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28 @param in The symmetric key you want to encrypt |
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29 @param inlen The length of the key to encrypt (octets) |
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30 @param out [out] The destination for the ciphertext |
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31 @param outlen [in/out] The max size and resulting size of the ciphertext |
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32 @param prng An active PRNG state |
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33 @param wprng The index of the PRNG you wish to use |
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34 @param hash The index of the hash you want to use |
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35 @param key The ECC key you want to encrypt to |
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36 @return CRYPT_OK if successful |
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37 */ |
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38 int ecc_encrypt_key(const unsigned char *in, unsigned long inlen, |
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39 unsigned char *out, unsigned long *outlen, |
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40 prng_state *prng, int wprng, int hash, |
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41 ecc_key *key) |
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42 { |
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43 unsigned char *pub_expt, *ecc_shared, *skey; |
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44 ecc_key pubkey; |
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45 unsigned long x, y, pubkeysize; |
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46 int err; |
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47 |
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48 LTC_ARGCHK(in != NULL); |
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49 LTC_ARGCHK(out != NULL); |
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50 LTC_ARGCHK(outlen != NULL); |
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51 LTC_ARGCHK(key != NULL); |
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52 |
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53 /* check that wprng/cipher/hash are not invalid */ |
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54 if ((err = prng_is_valid(wprng)) != CRYPT_OK) { |
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55 return err; |
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56 } |
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57 |
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58 if ((err = hash_is_valid(hash)) != CRYPT_OK) { |
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59 return err; |
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60 } |
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61 |
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62 if (inlen > hash_descriptor[hash].hashsize) { |
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63 return CRYPT_INVALID_HASH; |
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64 } |
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65 |
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66 /* make a random key and export the public copy */ |
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67 if ((err = ecc_make_key_ex(prng, wprng, &pubkey, key->dp)) != CRYPT_OK) { |
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68 return err; |
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69 } |
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70 |
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71 pub_expt = XMALLOC(ECC_BUF_SIZE); |
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72 ecc_shared = XMALLOC(ECC_BUF_SIZE); |
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73 skey = XMALLOC(MAXBLOCKSIZE); |
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74 if (pub_expt == NULL || ecc_shared == NULL || skey == NULL) { |
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75 if (pub_expt != NULL) { |
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76 XFREE(pub_expt); |
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77 } |
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78 if (ecc_shared != NULL) { |
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79 XFREE(ecc_shared); |
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80 } |
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81 if (skey != NULL) { |
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82 XFREE(skey); |
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83 } |
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84 ecc_free(&pubkey); |
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85 return CRYPT_MEM; |
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86 } |
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87 |
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88 pubkeysize = ECC_BUF_SIZE; |
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89 if ((err = ecc_export(pub_expt, &pubkeysize, PK_PUBLIC, &pubkey)) != CRYPT_OK) { |
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90 ecc_free(&pubkey); |
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91 goto LBL_ERR; |
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92 } |
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93 |
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94 /* make random key */ |
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95 x = ECC_BUF_SIZE; |
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96 if ((err = ecc_shared_secret(&pubkey, key, ecc_shared, &x)) != CRYPT_OK) { |
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97 ecc_free(&pubkey); |
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98 goto LBL_ERR; |
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99 } |
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100 ecc_free(&pubkey); |
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101 y = MAXBLOCKSIZE; |
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102 if ((err = hash_memory(hash, ecc_shared, x, skey, &y)) != CRYPT_OK) { |
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103 goto LBL_ERR; |
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104 } |
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105 |
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106 /* Encrypt key */ |
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107 for (x = 0; x < inlen; x++) { |
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108 skey[x] ^= in[x]; |
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109 } |
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110 |
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111 err = der_encode_sequence_multi(out, outlen, |
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112 LTC_ASN1_OBJECT_IDENTIFIER, hash_descriptor[hash].OIDlen, hash_descriptor[hash].OID, |
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113 LTC_ASN1_OCTET_STRING, pubkeysize, pub_expt, |
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114 LTC_ASN1_OCTET_STRING, inlen, skey, |
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115 LTC_ASN1_EOL, 0UL, NULL); |
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116 |
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117 LBL_ERR: |
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118 #ifdef LTC_CLEAN_STACK |
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119 /* clean up */ |
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120 zeromem(pub_expt, ECC_BUF_SIZE); |
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121 zeromem(ecc_shared, ECC_BUF_SIZE); |
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122 zeromem(skey, MAXBLOCKSIZE); |
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123 #endif |
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124 |
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125 XFREE(skey); |
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126 XFREE(ecc_shared); |
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127 XFREE(pub_expt); |
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128 |
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129 return err; |
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130 } |
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131 |
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132 #endif |
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133 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_encrypt_key.c,v $ */ |
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134 /* $Revision: 1.4 $ */ |
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135 /* $Date: 2006/11/21 00:10:18 $ */ |
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136 |
