annotate rsa_verify_hash.c @ 125:d16fc1b2223d libtomcrypt

merge of 8231809d2509aa54773443786e3123766438d924 and e30f886c9c14efb01f49297b3fb6b97c8868fd88
author Matt Johnston <matt@ucc.asn.au>
date Tue, 14 Sep 2004 13:28:31 +0000
parents 6362d3854bb4
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
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12 #include "mycrypt.h"
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13
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14 #ifdef MRSA
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15
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16 /* design then PSS depad */
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17 int rsa_verify_hash(const unsigned char *sig, unsigned long siglen,
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18 const unsigned char *msghash, unsigned long msghashlen,
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19 prng_state *prng, int prng_idx,
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20 int hash_idx, unsigned long saltlen,
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21 int *stat, rsa_key *key)
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22 {
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23 unsigned long modulus_bitlen, modulus_bytelen, x;
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24 int err;
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25 unsigned char *tmpbuf;
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26
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27 _ARGCHK(msghash != NULL);
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28 _ARGCHK(sig != NULL);
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29 _ARGCHK(stat != NULL);
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30 _ARGCHK(key != NULL);
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31
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32 /* valid hash ? */
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33 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
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34 return err;
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35 }
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36
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37 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
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38 return err;
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39 }
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40
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41 /* get modulus len in bits */
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42 modulus_bitlen = mp_count_bits(&(key->N));
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43
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44 /* outlen must be at least the size of the modulus */
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45 modulus_bytelen = mp_unsigned_bin_size(&(key->N));
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46 if (modulus_bytelen != siglen) {
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47 return CRYPT_INVALID_PACKET;
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48 }
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49
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50 /* allocate temp buffer for decoded sig */
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51 tmpbuf = XCALLOC(1, modulus_bytelen + 1);
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52 if (tmpbuf == NULL) {
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53 return CRYPT_MEM;
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54 }
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55
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56 /* RSA decode it */
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57 x = siglen;
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58 if ((err = rsa_exptmod(sig, siglen, tmpbuf, &x, PK_PUBLIC, prng, prng_idx, key)) != CRYPT_OK) {
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59 XFREE(tmpbuf);
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60 return err;
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61 }
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62
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63 /* PSS decode it */
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64 err = pkcs_1_pss_decode(msghash, msghashlen, tmpbuf, x, saltlen, hash_idx, modulus_bitlen, stat);
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65 XFREE(tmpbuf);
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66 return err;
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67 }
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68
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69 #endif /* MRSA */