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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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38 unsigned char buf[MAXBLOCKSIZE]; |
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39 unsigned char isha[MAXBLOCKSIZE]; |
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40 unsigned long hashsize, i; |
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41 int hash, err; |
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42 |
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43 _ARGCHK(hmac != NULL); |
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44 _ARGCHK(hashOut != NULL); |
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45 |
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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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54 // Get the hash of the first HMAC vector plus the data |
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55 if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) { |
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56 return err; |
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57 } |
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58 |
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59 // Create the second HMAC vector vector for step (3) |
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60 for(i=0; i < HMAC_BLOCKSIZE; i++) { |
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61 buf[i] = hmac->key[i] ^ 0x5C; |
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62 } |
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63 |
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64 // Now calculate the "outer" hash for step (5), (6), and (7) |
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65 hash_descriptor[hash].init(&hmac->md); |
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66 hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE); |
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67 hash_descriptor[hash].process(&hmac->md, isha, hashsize); |
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68 hash_descriptor[hash].done(&hmac->md, buf); |
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69 |
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70 // copy to output |
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71 for (i = 0; i < hashsize && i < *outlen; i++) { |
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72 hashOut[i] = buf[i]; |
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73 } |
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74 *outlen = i; |
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75 |
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76 #ifdef CLEAN_STACK |
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77 zeromem(isha, sizeof(buf)); |
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78 zeromem(buf, sizeof(isha)); |
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79 zeromem(hmac, sizeof(*hmac)); |
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80 #endif |
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81 return CRYPT_OK; |
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82 } |
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83 |
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84 #endif |
