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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 /* Submited by Dobes Vandermeer ([email protected]) */ |
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12 |
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13 #include "mycrypt.h" |
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14 |
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15 /* |
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16 (1) append zeros to the end of K to create a B byte string |
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17 (e.g., if K is of length 20 bytes and B=64, then K will be |
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18 appended with 44 zero bytes 0x00) |
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19 (2) XOR (bitwise exclusive-OR) the B byte string computed in step |
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20 (1) with ipad (ipad = the byte 0x36 repeated B times) |
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21 (3) append the stream of data 'text' to the B byte string resulting |
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22 from step (2) |
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23 (4) apply H to the stream generated in step (3) |
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24 (5) XOR (bitwise exclusive-OR) the B byte string computed in |
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25 step (1) with opad (opad = the byte 0x5C repeated B times.) |
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26 (6) append the H result from step (4) to the B byte string |
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27 resulting from step (5) |
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28 (7) apply H to the stream generated in step (6) and output |
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29 the result |
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30 */ |
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31 |
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32 #ifdef HMAC |
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33 |
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34 #define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize |
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35 |
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36 int hmac_done(hmac_state *hmac, unsigned char *hashOut, unsigned long *outlen) |
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37 { |
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143
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38 unsigned char *buf, *isha; |
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39 unsigned long hashsize, i; |
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40 int hash, err; |
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41 |
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143
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42 _ARGCHK(hmac != NULL); |
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43 _ARGCHK(hashOut != NULL); |
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44 |
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143
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45 /* test hash */ |
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46 hash = hmac->hash; |
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47 if((err = hash_is_valid(hash)) != CRYPT_OK) { |
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48 return err; |
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49 } |
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50 |
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51 /* get the hash message digest size */ |
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52 hashsize = hash_descriptor[hash].hashsize; |
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53 |
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143
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54 /* allocate buffers */ |
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55 buf = XMALLOC(HMAC_BLOCKSIZE); |
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56 isha = XMALLOC(hashsize); |
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57 if (buf == NULL || isha == NULL) { |
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58 if (buf != NULL) { |
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59 XFREE(buf); |
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60 } |
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61 if (isha != NULL) { |
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62 XFREE(isha); |
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63 } |
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64 return CRYPT_MEM; |
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65 } |
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66 |
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143
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67 /* Get the hash of the first HMAC vector plus the data */ |
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68 if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) { |
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69 goto __ERR; |
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70 } |
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71 |
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72 /* Create the second HMAC vector vector for step (3) */ |
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73 for(i=0; i < HMAC_BLOCKSIZE; i++) { |
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74 buf[i] = hmac->key[i] ^ 0x5C; |
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75 } |
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76 |
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143
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77 /* Now calculate the "outer" hash for step (5), (6), and (7) */ |
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78 if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) { |
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79 goto __ERR; |
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80 } |
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81 if ((err = hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE)) != CRYPT_OK) { |
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82 goto __ERR; |
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83 } |
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84 if ((err = hash_descriptor[hash].process(&hmac->md, isha, hashsize)) != CRYPT_OK) { |
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85 goto __ERR; |
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86 } |
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87 if ((err = hash_descriptor[hash].done(&hmac->md, buf)) != CRYPT_OK) { |
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88 goto __ERR; |
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89 } |
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90 |
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143
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91 /* copy to output */ |
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92 for (i = 0; i < hashsize && i < *outlen; i++) { |
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93 hashOut[i] = buf[i]; |
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94 } |
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95 *outlen = i; |
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96 |
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143
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97 err = CRYPT_OK; |
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98 __ERR: |
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99 XFREE(hmac->key); |
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100 #ifdef CLEAN_STACK |
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143
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101 zeromem(isha, hashsize); |
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102 zeromem(buf, hashsize); |
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103 zeromem(hmac, sizeof(*hmac)); |
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104 #endif |
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143
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105 |
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106 XFREE(isha); |
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107 XFREE(buf); |
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108 |
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109 return err; |
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110 } |
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111 |
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112 #endif |
