1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */
2 /* SPDX-License-Identifier: Unlicense */
3 #include "tomcrypt_private.h"
4
5 #ifdef LTC_RNG_GET_BYTES
6 /**
7 @file rng_get_bytes.c
8 portable way to get secure random bits to feed a PRNG (Tom St Denis)
9 */
10
11 #if defined(LTC_DEVRANDOM) && !defined(_WIN32)
12 /* on *NIX read /dev/random */
s_rng_nix(unsigned char * buf,unsigned long len,void (* callback)(void))13 static unsigned long s_rng_nix(unsigned char *buf, unsigned long len,
14 void (*callback)(void))
15 {
16 #ifdef LTC_NO_FILE
17 LTC_UNUSED_PARAM(callback);
18 LTC_UNUSED_PARAM(buf);
19 LTC_UNUSED_PARAM(len);
20 return 0;
21 #else
22 FILE *f;
23 unsigned long x;
24 LTC_UNUSED_PARAM(callback);
25 #ifdef LTC_TRY_URANDOM_FIRST
26 f = fopen("/dev/urandom", "rb");
27 if (f == NULL) {
28 f = fopen("/dev/random", "rb");
29 }
30 #else
31 f = fopen("/dev/random", "rb");
32 #endif /* LTC_TRY_URANDOM_FIRST */
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 /* LTC_DEVRANDOM */
51
52 #if !defined(_WIN32_WCE)
53
54 #define ANSI_RNG
55
s_rng_ansic(unsigned char * buf,unsigned long len,void (* callback)(void))56 static unsigned long s_rng_ansic(unsigned char *buf, unsigned long len,
57 void (*callback)(void))
58 {
59 clock_t t1;
60 int l, acc, bits, a, b;
61
62 l = len;
63 bits = 8;
64 acc = a = b = 0;
65 while (len--) {
66 if (callback != NULL) callback();
67 while (bits--) {
68 do {
69 t1 = XCLOCK(); while (t1 == XCLOCK()) a ^= 1;
70 t1 = XCLOCK(); while (t1 == XCLOCK()) b ^= 1;
71 } while (a == b);
72 acc = (acc << 1) | a;
73 }
74 *buf++ = acc;
75 acc = 0;
76 bits = 8;
77 }
78 return l;
79 }
80
81 #endif
82
83 /* Try the Microsoft CSP */
84 #if defined(_WIN32) || defined(_WIN32_WCE)
85 #if defined(LTC_WIN32_BCRYPT)
86
87 #include <windows.h>
88 #include <bcrypt.h>
89 #pragma comment(lib, "bcrypt.lib")
90
s_rng_win32(unsigned char * buf,unsigned long len,void (* callback)(void))91 static unsigned long s_rng_win32(unsigned char *buf, unsigned long len,
92 void (*callback)(void))
93 {
94 LTC_UNUSED_PARAM(callback);
95
96 return BCRYPT_SUCCESS(BCryptGenRandom(NULL, (PUCHAR)buf, (ULONG)len, BCRYPT_USE_SYSTEM_PREFERRED_RNG)) ? len : 0;
97 }
98
99 #else
100
101 #ifndef _WIN32_WINNT
102 #define _WIN32_WINNT 0x0501
103 #endif
104 #ifndef WINVER
105 #define WINVER 0x0501
106 #endif
107
108 #define WIN32_LEAN_AND_MEAN
109 #include <windows.h>
110 #include <wincrypt.h>
111
s_rng_win32(unsigned char * buf,unsigned long len,void (* callback)(void))112 static unsigned long s_rng_win32(unsigned char *buf, unsigned long len,
113 void (*callback)(void))
114 {
115 LTC_UNUSED_PARAM(callback);
116
117 static HCRYPTPROV hProv = 0;
118 if (hProv == 0) {
119 HCRYPTPROV h = 0;
120 if (!CryptAcquireContextW(&h, NULL, MS_DEF_PROV_W, PROV_RSA_FULL,
121 (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
122 !CryptAcquireContextW(&h, NULL, MS_DEF_PROV_W, PROV_RSA_FULL,
123 CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET)) {
124 return 0;
125 }
126 hProv = h;
127 }
128
129 return CryptGenRandom(hProv, (DWORD)len, (BYTE *)buf) == TRUE ? len : 0;
130 }
131 #endif /* Old WIN32 versions */
132 #endif /* WIN32 */
133
134 /**
135 Read the system RNG
136 @param out Destination
137 @param outlen Length desired (octets)
138 @param callback Pointer to void function to act as "callback" when RNG is slow. This can be NULL
139 @return Number of octets read
140 */
rng_get_bytes(unsigned char * out,unsigned long outlen,void (* callback)(void))141 unsigned long rng_get_bytes(unsigned char *out, unsigned long outlen,
142 void (*callback)(void))
143 {
144 unsigned long x;
145
146 LTC_ARGCHK(out != NULL);
147
148 #ifdef LTC_PRNG_ENABLE_LTC_RNG
149 if (ltc_rng) {
150 x = ltc_rng(out, outlen, callback);
151 if (x != 0) {
152 return x;
153 }
154 }
155 #endif
156
157 #if defined(_WIN32) || defined(_WIN32_WCE)
158 x = s_rng_win32(out, outlen, callback); if (x != 0) { return x; }
159 #elif defined(LTC_DEVRANDOM)
160 x = s_rng_nix(out, outlen, callback); if (x != 0) { return x; }
161 #endif
162 #ifdef ANSI_RNG
163 x = s_rng_ansic(out, outlen, callback); if (x != 0) { return x; }
164 #endif
165 return 0;
166 }
167 #endif /* #ifdef LTC_RNG_GET_BYTES */
168