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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 /* PKCS #5, Algorithm #2 */ |
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14 #ifdef PKCS_5 |
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15 |
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16 int pkcs_5_alg2(const unsigned char *password, unsigned long password_len, |
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17 const unsigned char *salt, unsigned long salt_len, |
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18 int iteration_count, int hash_idx, |
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19 unsigned char *out, unsigned long *outlen) |
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20 { |
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21 int err, itts; |
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22 unsigned long stored, left, x, y, blkno; |
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143
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23 unsigned char *buf[2]; |
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24 hmac_state *hmac; |
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3
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25 |
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26 _ARGCHK(password != NULL); |
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27 _ARGCHK(salt != NULL); |
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28 _ARGCHK(out != NULL); |
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29 _ARGCHK(outlen != NULL); |
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30 |
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31 /* test hash IDX */ |
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32 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { |
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33 return err; |
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34 } |
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35 |
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143
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36 buf[0] = XMALLOC(MAXBLOCKSIZE * 2); |
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37 hmac = XMALLOC(sizeof(hmac_state)); |
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38 if (hmac == NULL || buf[0] == NULL) { |
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39 if (hmac != NULL) { |
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40 XFREE(hmac); |
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41 } |
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42 if (buf[0] != NULL) { |
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43 XFREE(buf[0]); |
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44 } |
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45 return CRYPT_MEM; |
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46 } |
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47 /* buf[1] points to the second block of MAXBLOCKSIZE bytes */ |
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48 buf[1] = buf[0] + MAXBLOCKSIZE; |
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49 |
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50 left = *outlen; |
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51 blkno = 1; |
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52 stored = 0; |
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53 while (left != 0) { |
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54 /* process block number blkno */ |
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143
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55 zeromem(buf[0], MAXBLOCKSIZE*2); |
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56 |
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57 /* store current block number and increment for next pass */ |
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58 STORE32H(blkno, buf[1]); |
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59 ++blkno; |
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60 |
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61 /* get PRF(P, S||int(blkno)) */ |
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143
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62 if ((err = hmac_init(hmac, hash_idx, password, password_len)) != CRYPT_OK) { |
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63 goto __ERR; |
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3
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64 } |
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143
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65 if ((err = hmac_process(hmac, salt, salt_len)) != 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 = hmac_process(hmac, buf[1], 4)) != CRYPT_OK) { |
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69 goto __ERR; |
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3
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70 } |
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143
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71 x = MAXBLOCKSIZE; |
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72 if ((err = hmac_done(hmac, buf[0], &x)) != CRYPT_OK) { |
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73 goto __ERR; |
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3
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74 } |
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75 |
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76 /* now compute repeated and XOR it in buf[1] */ |
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143
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77 XMEMCPY(buf[1], buf[0], x); |
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78 for (itts = 1; itts < iteration_count; ++itts) { |
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79 if ((err = hmac_memory(hash_idx, password, password_len, buf[0], x, buf[0], &x)) != CRYPT_OK) { |
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143
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80 goto __ERR; |
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81 } |
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82 for (y = 0; y < x; y++) { |
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83 buf[1][y] ^= buf[0][y]; |
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84 } |
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85 } |
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86 |
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87 /* now emit upto x bytes of buf[1] to output */ |
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88 for (y = 0; y < x && left != 0; ++y) { |
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89 out[stored++] = buf[1][y]; |
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90 --left; |
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91 } |
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92 } |
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93 *outlen = stored; |
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94 |
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143
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95 err = CRYPT_OK; |
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96 __ERR: |
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97 #ifdef CLEAN_STACK |
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143
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98 zeromem(buf[0], MAXBLOCKSIZE*2); |
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99 zeromem(hmac, sizeof(hmac_state)); |
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100 #endif |
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143
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101 |
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102 XFREE(hmac); |
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103 XFREE(buf[0]); |
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104 |
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105 return err; |
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3
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106 } |
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107 |
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108 #endif |
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109 |
