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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 /* portable way to get secure random bits to feed a PRNG */ |
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12 #include "mycrypt.h" |
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13 |
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14 #ifdef DEVRANDOM |
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15 /* on *NIX read /dev/random */ |
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16 static unsigned long rng_nix(unsigned char *buf, unsigned long len, |
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17 void (*callback)(void)) |
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18 { |
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19 #ifdef NO_FILE |
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20 return 0; |
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21 #else |
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22 FILE *f; |
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23 unsigned long x; |
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24 #ifdef TRY_URANDOM_FIRST |
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25 f = fopen("/dev/urandom", "rb"); |
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26 if (f == NULL) |
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27 #endif /* TRY_URANDOM_FIRST */ |
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28 f = fopen("/dev/random", "rb"); |
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29 |
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30 if (f == NULL) { |
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31 return 0; |
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32 } |
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33 |
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34 /* disable buffering */ |
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35 if (setvbuf(f, NULL, _IONBF, 0) != 0) { |
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36 fclose(f); |
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37 return 0; |
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38 } |
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39 |
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40 x = (unsigned long)fread(buf, 1, (size_t)len, f); |
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41 fclose(f); |
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42 return x; |
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43 #endif /* NO_FILE */ |
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44 } |
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45 |
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46 #endif /* DEVRANDOM */ |
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47 |
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48 /* on ANSI C platforms with 100 < CLOCKS_PER_SEC < 10000 */ |
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49 #if defined(CLOCKS_PER_SEC) |
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50 |
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51 #define ANSI_RNG |
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52 |
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53 static unsigned long rng_ansic(unsigned char *buf, unsigned long len, |
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54 void (*callback)(void)) |
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55 { |
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56 clock_t t1; |
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57 int l, acc, bits, a, b; |
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58 |
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59 if (XCLOCKS_PER_SEC < 100 || XCLOCKS_PER_SEC > 10000) { |
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60 return 0; |
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61 } |
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62 |
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63 l = len; |
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64 bits = 8; |
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65 acc = a = b = 0; |
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66 while (len--) { |
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67 if (callback != NULL) callback(); |
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68 while (bits--) { |
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69 do { |
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70 t1 = XCLOCK(); while (t1 == XCLOCK()) a ^= 1; |
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71 t1 = XCLOCK(); while (t1 == XCLOCK()) b ^= 1; |
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72 } while (a == b); |
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73 acc = (acc << 1) | a; |
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74 } |
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75 *buf++ = acc; |
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76 acc = 0; |
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77 bits = 8; |
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78 } |
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79 acc = bits = a = b = 0; |
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80 return l; |
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81 } |
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82 |
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83 #endif |
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84 |
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85 /* Try the Microsoft CSP */ |
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86 #ifdef WIN32 |
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87 #define _WIN32_WINNT 0x0400 |
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88 #include <windows.h> |
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89 #include <wincrypt.h> |
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90 |
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91 static unsigned long rng_win32(unsigned char *buf, unsigned long len, |
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92 void (*callback)(void)) |
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93 { |
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94 HCRYPTPROV hProv = 0; |
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95 if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, |
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96 (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) && |
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97 !CryptAcquireContext (&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, |
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98 CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET)) |
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99 return 0; |
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100 |
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101 if (CryptGenRandom(hProv, len, buf) == TRUE) { |
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102 CryptReleaseContext(hProv, 0); |
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103 return len; |
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104 } else { |
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105 CryptReleaseContext(hProv, 0); |
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106 return 0; |
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107 } |
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108 } |
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109 |
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110 #endif /* WIN32 */ |
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111 |
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112 unsigned long rng_get_bytes(unsigned char *buf, unsigned long len, |
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113 void (*callback)(void)) |
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114 { |
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115 unsigned long x; |
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116 |
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117 _ARGCHK(buf != NULL); |
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118 |
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119 #if defined(DEVRANDOM) |
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120 x = rng_nix(buf, len, callback); if (x != 0) { return x; } |
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121 #endif |
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122 #ifdef WIN32 |
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123 x = rng_win32(buf, len, callback); if (x != 0) { return x; } |
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124 #endif |
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125 #ifdef ANSI_RNG |
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126 x = rng_ansic(buf, len, callback); if (x != 0) { return x; } |
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127 #endif |
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128 return 0; |
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129 } |
