annotate src/pk/pkcs1/pkcs_1_oaep_encode.c @ 380:d5faf4814ddb libtomcrypt-orig libtomcrypt-1.16

Update to LibTomCrypt 1.16
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 02:22:00 +0000
parents 59400faa4b44
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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2 *
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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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 *
380
d5faf4814ddb Update to LibTomCrypt 1.16
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9 * Tom St Denis, [email protected], http://libtomcrypt.com
280
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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 pkcs_1_oaep_encode.c
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15 OAEP Padding for PKCS #1, Tom St Denis
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16 */
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17
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18 #ifdef PKCS_1
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19
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20 /**
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21 PKCS #1 v2.00 OAEP encode
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22 @param msg The data to encode
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23 @param msglen The length of the data to encode (octets)
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24 @param lparam A session or system parameter (can be NULL)
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25 @param lparamlen The length of the lparam data
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26 @param modulus_bitlen The bit length of the RSA modulus
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27 @param prng An active PRNG state
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28 @param prng_idx The index of the PRNG desired
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29 @param hash_idx The index of the hash desired
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30 @param out [out] The destination for the encoded data
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31 @param outlen [in/out] The max size and resulting size of the encoded data
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32 @return CRYPT_OK if successful
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33 */
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34 int pkcs_1_oaep_encode(const unsigned char *msg, unsigned long msglen,
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35 const unsigned char *lparam, unsigned long lparamlen,
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36 unsigned long modulus_bitlen, prng_state *prng,
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37 int prng_idx, int hash_idx,
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38 unsigned char *out, unsigned long *outlen)
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39 {
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40 unsigned char *DB, *seed, *mask;
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41 unsigned long hLen, x, y, modulus_len;
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42 int err;
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43
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44 LTC_ARGCHK(msg != NULL);
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45 LTC_ARGCHK(out != NULL);
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46 LTC_ARGCHK(outlen != NULL);
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47
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48 /* test valid hash */
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49 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
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50 return err;
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51 }
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52
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53 /* valid prng */
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54 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
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55 return err;
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56 }
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57
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58 hLen = hash_descriptor[hash_idx].hashsize;
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59 modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);
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60
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61 /* test message size */
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62 if ((2*hLen >= (modulus_len - 2)) || (msglen > (modulus_len - 2*hLen - 2))) {
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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63 return CRYPT_PK_INVALID_SIZE;
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64 }
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65
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66 /* allocate ram for DB/mask/salt of size modulus_len */
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67 DB = XMALLOC(modulus_len);
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68 mask = XMALLOC(modulus_len);
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69 seed = XMALLOC(hLen);
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70 if (DB == NULL || mask == NULL || seed == NULL) {
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71 if (DB != NULL) {
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72 XFREE(DB);
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73 }
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74 if (mask != NULL) {
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75 XFREE(mask);
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76 }
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77 if (seed != NULL) {
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78 XFREE(seed);
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79 }
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80 return CRYPT_MEM;
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81 }
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82
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83 /* get lhash */
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84 /* DB == lhash || PS || 0x01 || M, PS == k - mlen - 2hlen - 2 zeroes */
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85 x = modulus_len;
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86 if (lparam != NULL) {
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87 if ((err = hash_memory(hash_idx, lparam, lparamlen, DB, &x)) != CRYPT_OK) {
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88 goto LBL_ERR;
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89 }
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90 } else {
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91 /* can't pass hash_memory a NULL so use DB with zero length */
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92 if ((err = hash_memory(hash_idx, DB, 0, DB, &x)) != CRYPT_OK) {
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93 goto LBL_ERR;
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94 }
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95 }
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96
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97 /* append PS then 0x01 (to lhash) */
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98 x = hLen;
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99 y = modulus_len - msglen - 2*hLen - 2;
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100 XMEMSET(DB+x, 0, y);
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101 x += y;
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102
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103 /* 0x01 byte */
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104 DB[x++] = 0x01;
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105
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106 /* message (length = msglen) */
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107 XMEMCPY(DB+x, msg, msglen);
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108 x += msglen;
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109
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110 /* now choose a random seed */
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111 if (prng_descriptor[prng_idx].read(seed, hLen, prng) != hLen) {
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112 err = CRYPT_ERROR_READPRNG;
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113 goto LBL_ERR;
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114 }
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115
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116 /* compute MGF1 of seed (k - hlen - 1) */
380
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117 if ((err = pkcs_1_mgf1(hash_idx, seed, hLen, mask, modulus_len - hLen - 1)) != CRYPT_OK) {
280
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118 goto LBL_ERR;
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119 }
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120
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121 /* xor against DB */
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122 for (y = 0; y < (modulus_len - hLen - 1); y++) {
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diff changeset
123 DB[y] ^= mask[y];
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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diff changeset
124 }
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diff changeset
125
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diff changeset
126 /* compute MGF1 of maskedDB (hLen) */
380
d5faf4814ddb Update to LibTomCrypt 1.16
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parents: 280
diff changeset
127 if ((err = pkcs_1_mgf1(hash_idx, DB, modulus_len - hLen - 1, mask, hLen)) != CRYPT_OK) {
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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128 goto LBL_ERR;
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129 }
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130
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131 /* XOR against seed */
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diff changeset
132 for (y = 0; y < hLen; y++) {
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133 seed[y] ^= mask[y];
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134 }
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135
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diff changeset
136 /* create string of length modulus_len */
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parents:
diff changeset
137 if (*outlen < modulus_len) {
380
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parents: 280
diff changeset
138 *outlen = modulus_len;
280
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139 err = CRYPT_BUFFER_OVERFLOW;
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parents:
diff changeset
140 goto LBL_ERR;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
141 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
142
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
143 /* start output which is 0x00 || maskedSeed || maskedDB */
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
144 x = 0;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
145 out[x++] = 0x00;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
146 XMEMCPY(out+x, seed, hLen);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
147 x += hLen;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
148 XMEMCPY(out+x, DB, modulus_len - hLen - 1);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
149 x += modulus_len - hLen - 1;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
150
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
151 *outlen = x;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
152
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
153 err = CRYPT_OK;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
154 LBL_ERR:
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
155 #ifdef LTC_CLEAN_STACK
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
156 zeromem(DB, modulus_len);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
157 zeromem(seed, hLen);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
158 zeromem(mask, modulus_len);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
159 #endif
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
160
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
161 XFREE(seed);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
162 XFREE(mask);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
163 XFREE(DB);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
164
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
165 return err;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
166 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
167
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
168 #endif /* PKCS_1 */
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
169
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
170
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
171 /* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_oaep_encode.c,v $ */
380
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
172 /* $Revision: 1.7 $ */
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
173 /* $Date: 2006/06/16 21:53:41 $ */