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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 #include "mycrypt.h" |
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12 |
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13 /* The Mask Generation Function (MGF1) for PKCS #1 -- Tom St Denis */ |
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14 |
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15 #ifdef PKCS_1 |
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16 |
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17 int pkcs_1_mgf1(const unsigned char *seed, unsigned long seedlen, |
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18 int hash_idx, |
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19 unsigned char *mask, unsigned long masklen) |
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20 { |
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21 unsigned long hLen, counter, x; |
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22 int err; |
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143
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23 hash_state *md; |
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24 unsigned char *buf; |
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3
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25 |
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26 _ARGCHK(seed != NULL); |
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27 _ARGCHK(mask != NULL); |
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28 |
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29 /* ensure valid hash */ |
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30 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { |
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31 return err; |
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32 } |
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33 |
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34 /* get hash output size */ |
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35 hLen = hash_descriptor[hash_idx].hashsize; |
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36 |
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143
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37 /* allocate memory */ |
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38 md = XMALLOC(sizeof(hash_state)); |
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39 buf = XMALLOC(hLen); |
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40 if (md == NULL || buf == NULL) { |
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41 if (md != NULL) { |
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42 XFREE(md); |
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43 } |
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44 if (buf != NULL) { |
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45 XFREE(buf); |
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46 } |
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47 return CRYPT_MEM; |
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48 } |
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49 |
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3
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50 /* start counter */ |
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51 counter = 0; |
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52 |
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53 while (masklen > 0) { |
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54 /* handle counter */ |
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55 STORE32H(counter, buf); |
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56 ++counter; |
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57 |
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58 /* get hash of seed || counter */ |
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143
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59 if ((err = hash_descriptor[hash_idx].init(md)) != CRYPT_OK) { |
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60 goto __ERR; |
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61 } |
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62 if ((err = hash_descriptor[hash_idx].process(md, seed, seedlen)) != CRYPT_OK) { |
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63 goto __ERR; |
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64 } |
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143
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65 if ((err = hash_descriptor[hash_idx].process(md, buf, 4)) != CRYPT_OK) { |
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66 goto __ERR; |
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67 } |
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143
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68 if ((err = hash_descriptor[hash_idx].done(md, buf)) != CRYPT_OK) { |
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69 goto __ERR; |
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70 } |
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71 |
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72 /* store it */ |
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73 for (x = 0; x < hLen && masklen > 0; x++, masklen--) { |
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74 *mask++ = buf[x]; |
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75 } |
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76 } |
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77 |
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143
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78 err = CRYPT_OK; |
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79 __ERR: |
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80 #ifdef CLEAN_STACK |
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81 zeromem(buf, hLen); |
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82 zeromem(md, sizeof(hash_state)); |
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83 #endif |
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84 |
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85 XFREE(buf); |
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86 XFREE(md); |
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87 |
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88 return err; |
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3
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89 } |
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90 |
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91 #endif /* PKCS_1 */ |
