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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 /* hmac_file added by Tom St Denis */ |
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37 int hmac_file(int hash, const char *fname, |
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38 const unsigned char *key, unsigned long keylen, |
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39 unsigned char *dst, unsigned long *dstlen) |
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40 { |
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41 #ifdef NO_FILE |
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42 return CRYPT_NOP; |
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43 #else |
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44 hmac_state hmac; |
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45 FILE *in; |
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46 unsigned char buf[512]; |
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47 size_t x; |
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48 int err; |
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49 |
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50 _ARGCHK(fname != NULL); |
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51 _ARGCHK(key != NULL); |
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52 _ARGCHK(dst != NULL); |
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53 _ARGCHK(dstlen != NULL); |
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54 |
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55 if((err = hash_is_valid(hash)) != CRYPT_OK) { |
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56 return err; |
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57 } |
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58 |
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59 if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) { |
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60 return err; |
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61 } |
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62 |
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63 in = fopen(fname, "rb"); |
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64 if (in == NULL) { |
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65 return CRYPT_FILE_NOTFOUND; |
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66 } |
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67 |
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68 /* process the file contents */ |
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69 do { |
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70 x = fread(buf, 1, sizeof(buf), in); |
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71 if ((err = hmac_process(&hmac, buf, (unsigned long)x)) != CRYPT_OK) { |
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72 /* we don't trap this error since we're already returning an error! */ |
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73 fclose(in); |
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74 return err; |
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75 } |
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76 } while (x == sizeof(buf)); |
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77 |
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78 if (fclose(in) != 0) { |
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79 return CRYPT_ERROR; |
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80 } |
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81 |
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82 /* get final hmac */ |
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83 if ((err = hmac_done(&hmac, dst, dstlen)) != CRYPT_OK) { |
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84 return err; |
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85 } |
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86 |
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87 #ifdef CLEAN_STACK |
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88 /* clear memory */ |
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89 zeromem(buf, sizeof(buf)); |
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90 #endif |
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91 return CRYPT_OK; |
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92 #endif |
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93 } |
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94 |
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95 #endif |
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96 |
