annotate hmac_done.c @ 0:d7da3b1e1540 libtomcrypt

put back the 0.95 makefile which was inadvertently merged over
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:21:40 +0000
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children 5d99163f7e32
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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