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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.com |
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10 */ |
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11 #include "tomcrypt.h" |
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12 |
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13 /** |
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14 @file katja_encrypt_key.c |
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15 Katja PKCS-style OAEP encryption, Tom St Denis |
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16 */ |
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17 |
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18 #ifdef MKAT |
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19 |
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20 /** |
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21 (PKCS #1 v2.0) OAEP pad then encrypt |
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22 @param in The plaintext |
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23 @param inlen The length of the plaintext (octets) |
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24 @param out [out] The ciphertext |
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25 @param outlen [in/out] The max size and resulting size of the ciphertext |
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26 @param lparam The system "lparam" for the encryption |
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27 @param lparamlen The length of lparam (octets) |
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28 @param prng An active PRNG |
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29 @param prng_idx The index of the desired prng |
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30 @param hash_idx The index of the desired hash |
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31 @param key The Katja key to encrypt to |
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32 @return CRYPT_OK if successful |
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33 */ |
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34 int katja_encrypt_key(const unsigned char *in, unsigned long inlen, |
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35 unsigned char *out, unsigned long *outlen, |
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36 const unsigned char *lparam, unsigned long lparamlen, |
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37 prng_state *prng, int prng_idx, int hash_idx, katja_key *key) |
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38 { |
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39 unsigned long modulus_bitlen, modulus_bytelen, x; |
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40 int err; |
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41 |
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42 LTC_ARGCHK(in != NULL); |
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43 LTC_ARGCHK(out != NULL); |
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44 LTC_ARGCHK(outlen != NULL); |
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45 LTC_ARGCHK(key != NULL); |
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46 |
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47 /* valid prng and hash ? */ |
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48 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) { |
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49 return err; |
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50 } |
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51 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { |
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52 return err; |
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53 } |
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54 |
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55 /* get modulus len in bits */ |
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56 modulus_bitlen = mp_count_bits((key->N)); |
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57 |
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58 /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */ |
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59 modulus_bitlen = ((modulus_bitlen << 1) / 3); |
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60 |
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61 /* round down to next byte */ |
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62 modulus_bitlen -= (modulus_bitlen & 7) + 8; |
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63 |
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64 /* outlen must be at least the size of the modulus */ |
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65 modulus_bytelen = mp_unsigned_bin_size((key->N)); |
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66 if (modulus_bytelen > *outlen) { |
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67 *outlen = modulus_bytelen; |
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68 return CRYPT_BUFFER_OVERFLOW; |
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69 } |
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70 |
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71 /* OAEP pad the key */ |
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72 x = *outlen; |
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73 if ((err = pkcs_1_oaep_encode(in, inlen, lparam, |
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74 lparamlen, modulus_bitlen, prng, prng_idx, hash_idx, |
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75 out, &x)) != CRYPT_OK) { |
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76 return err; |
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77 } |
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78 |
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79 /* Katja exptmod the OAEP pad */ |
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80 return katja_exptmod(out, x, out, outlen, PK_PUBLIC, key); |
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81 } |
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82 |
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83 #endif /* MRSA */ |
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84 |
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85 /* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_encrypt_key.c,v $ */ |
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86 /* $Revision: 1.5 $ */ |
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87 /* $Date: 2006/06/16 21:53:41 $ */ |
