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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 /* decrypt then OAEP depad */ |
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17 int rsa_decrypt_key(const unsigned char *in, unsigned long inlen, |
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18 unsigned char *outkey, unsigned long *keylen, |
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19 const unsigned char *lparam, unsigned long lparamlen, |
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20 prng_state *prng, int prng_idx, |
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21 int hash_idx, int *res, |
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22 rsa_key *key) |
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23 { |
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24 unsigned long modulus_bitlen, modulus_bytelen, x; |
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25 int err; |
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26 |
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27 _ARGCHK(outkey != NULL); |
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28 _ARGCHK(keylen != NULL); |
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29 _ARGCHK(key != NULL); |
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30 _ARGCHK(res != 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 /* get modulus len in bits */ |
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38 modulus_bitlen = mp_count_bits(&(key->N)); |
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39 |
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40 /* outlen must be at least the size of the modulus */ |
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41 modulus_bytelen = mp_unsigned_bin_size(&(key->N)); |
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42 if (modulus_bytelen != inlen) { |
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43 return CRYPT_INVALID_PACKET; |
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44 } |
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45 |
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46 /* rsa decode the packet */ |
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47 x = *keylen; |
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48 if ((err = rsa_exptmod(in, inlen, outkey, &x, PK_PRIVATE, prng, prng_idx, key)) != CRYPT_OK) { |
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49 return err; |
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50 } |
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51 |
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52 /* now OAEP decode the packet */ |
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53 return pkcs_1_oaep_decode(outkey, x, lparam, lparamlen, modulus_bitlen, hash_idx, |
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54 outkey, keylen, res); |
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55 } |
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56 |
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57 #endif /* MRSA */ |
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58 |
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59 |
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60 |
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61 |
