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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 /* PKCS #1 v1.5 pad then sign */ |
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17 int rsa_v15_sign_hash(const unsigned char *msghash, unsigned long msghashlen, |
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18 unsigned char *sig, unsigned long *siglen, |
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19 prng_state *prng, int prng_idx, |
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20 int hash_idx, rsa_key *key) |
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21 { |
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22 unsigned long modulus_bitlen, modulus_bytelen, x; |
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23 int err; |
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24 |
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25 _ARGCHK(msghash != NULL); |
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26 _ARGCHK(sig != NULL); |
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27 _ARGCHK(siglen != NULL); |
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28 _ARGCHK(key != NULL); |
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29 |
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30 /* valid prng and hash ? */ |
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31 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) { |
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32 return err; |
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33 } |
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34 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { |
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35 return err; |
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36 } |
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37 |
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38 /* get modulus len in bits */ |
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39 modulus_bitlen = mp_count_bits(&(key->N)); |
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40 |
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41 /* outlen must be at least the size of the modulus */ |
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42 modulus_bytelen = mp_unsigned_bin_size(&(key->N)); |
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43 if (modulus_bytelen > *siglen) { |
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44 return CRYPT_BUFFER_OVERFLOW; |
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45 } |
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46 |
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47 /* PKCS #1 v1.5 pad the key */ |
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48 x = *siglen; |
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49 if ((err = pkcs_1_v15_sa_encode(msghash, msghashlen, hash_idx, modulus_bitlen, sig, &x)) != CRYPT_OK) { |
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50 return err; |
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51 } |
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52 |
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53 /* RSA encode it */ |
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54 return rsa_exptmod(sig, x, sig, siglen, PK_PRIVATE, prng, prng_idx, key); |
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55 } |
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56 |
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57 #endif |
