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comparison libtomcrypt/src/prngs/rng_get_bytes.c @ 285:1b9e69c058d2

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
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children 0cbe8f6dbf9e
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281:997e6f7dc01e 285:1b9e69c058d2
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, [email protected], http://libtomcrypt.org
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file rng_get_bytes.c
15 portable way to get secure random bits to feed a PRNG (Tom St Denis)
16 */
17
18 #ifdef DEVRANDOM
19 /* on *NIX read /dev/random */
20 static unsigned long rng_nix(unsigned char *buf, unsigned long len,
21 void (*callback)(void))
22 {
23 #ifdef LTC_NO_FILE
24 return 0;
25 #else
26 FILE *f;
27 unsigned long x;
28 #ifdef TRY_URANDOM_FIRST
29 f = fopen("/dev/urandom", "rb");
30 if (f == NULL)
31 #endif /* TRY_URANDOM_FIRST */
32 f = fopen("/dev/random", "rb");
33
34 if (f == NULL) {
35 return 0;
36 }
37
38 /* disable buffering */
39 if (setvbuf(f, NULL, _IONBF, 0) != 0) {
40 fclose(f);
41 return 0;
42 }
43
44 x = (unsigned long)fread(buf, 1, (size_t)len, f);
45 fclose(f);
46 return x;
47 #endif /* LTC_NO_FILE */
48 }
49
50 #endif /* DEVRANDOM */
51
52 /* on ANSI C platforms with 100 < CLOCKS_PER_SEC < 10000 */
53 #if defined(CLOCKS_PER_SEC)
54
55 #define ANSI_RNG
56
57 static unsigned long rng_ansic(unsigned char *buf, unsigned long len,
58 void (*callback)(void))
59 {
60 clock_t t1;
61 int l, acc, bits, a, b;
62
63 if (XCLOCKS_PER_SEC < 100 || XCLOCKS_PER_SEC > 10000) {
64 return 0;
65 }
66
67 l = len;
68 bits = 8;
69 acc = a = b = 0;
70 while (len--) {
71 if (callback != NULL) callback();
72 while (bits--) {
73 do {
74 t1 = XCLOCK(); while (t1 == XCLOCK()) a ^= 1;
75 t1 = XCLOCK(); while (t1 == XCLOCK()) b ^= 1;
76 } while (a == b);
77 acc = (acc << 1) | a;
78 }
79 *buf++ = acc;
80 acc = 0;
81 bits = 8;
82 }
83 acc = bits = a = b = 0;
84 return l;
85 }
86
87 #endif
88
89 /* Try the Microsoft CSP */
90 #ifdef WIN32
91 #define _WIN32_WINNT 0x0400
92 #include <windows.h>
93 #include <wincrypt.h>
94
95 static unsigned long rng_win32(unsigned char *buf, unsigned long len,
96 void (*callback)(void))
97 {
98 HCRYPTPROV hProv = 0;
99 if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
100 (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
101 !CryptAcquireContext (&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
102 CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET))
103 return 0;
104
105 if (CryptGenRandom(hProv, len, buf) == TRUE) {
106 CryptReleaseContext(hProv, 0);
107 return len;
108 } else {
109 CryptReleaseContext(hProv, 0);
110 return 0;
111 }
112 }
113
114 #endif /* WIN32 */
115
116 /**
117 Read the system RNG
118 @param out Destination
119 @param outlen Length desired (octets)
120 @param callback Pointer to void function to act as "callback" when RNG is slow. This can be NULL
121 @return Number of octets read
122 */
123 unsigned long rng_get_bytes(unsigned char *out, unsigned long outlen,
124 void (*callback)(void))
125 {
126 unsigned long x;
127
128 LTC_ARGCHK(out != NULL);
129
130 #if defined(DEVRANDOM)
131 x = rng_nix(out, outlen, callback); if (x != 0) { return x; }
132 #endif
133 #ifdef WIN32
134 x = rng_win32(out, outlen, callback); if (x != 0) { return x; }
135 #endif
136 #ifdef ANSI_RNG
137 x = rng_ansic(out, outlen, callback); if (x != 0) { return x; }
138 #endif
139 return 0;
140 }
141
142 /* $Source: /cvs/libtom/libtomcrypt/src/prngs/rng_get_bytes.c,v $ */
143 /* $Revision: 1.3 $ */
144 /* $Date: 2005/05/05 14:35:59 $ */