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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
#include "tomcrypt.h"
#ifdef LTC_RNG_GET_BYTES
/**
@file rng_get_bytes.c
portable way to get secure random bits to feed a PRNG (Tom St Denis)
*/
#if defined(LTC_DEVRANDOM) && !defined(_WIN32)
/* on *NIX read /dev/random */
static unsigned long _rng_nix(unsigned char *buf, unsigned long len,
void (*callback)(void))
{
#ifdef LTC_NO_FILE
LTC_UNUSED_PARAM(callback);
LTC_UNUSED_PARAM(buf);
LTC_UNUSED_PARAM(len);
return 0;
#else
FILE *f;
unsigned long x;
LTC_UNUSED_PARAM(callback);
#ifdef LTC_TRY_URANDOM_FIRST
f = fopen("/dev/urandom", "rb");
if (f == NULL)
#endif /* LTC_TRY_URANDOM_FIRST */
f = fopen("/dev/random", "rb");
if (f == NULL) {
return 0;
}
/* disable buffering */
if (setvbuf(f, NULL, _IONBF, 0) != 0) {
fclose(f);
return 0;
}
x = (unsigned long)fread(buf, 1, (size_t)len, f);
fclose(f);
return x;
#endif /* LTC_NO_FILE */
}
#endif /* LTC_DEVRANDOM */
#if !defined(_WIN32_WCE)
#define ANSI_RNG
static unsigned long _rng_ansic(unsigned char *buf, unsigned long len,
void (*callback)(void))
{
clock_t t1;
int l, acc, bits, a, b;
l = len;
bits = 8;
acc = a = b = 0;
while (len--) {
if (callback != NULL) callback();
while (bits--) {
do {
t1 = XCLOCK(); while (t1 == XCLOCK()) a ^= 1;
t1 = XCLOCK(); while (t1 == XCLOCK()) b ^= 1;
} while (a == b);
acc = (acc << 1) | a;
}
*buf++ = acc;
acc = 0;
bits = 8;
}
return l;
}
#endif
/* Try the Microsoft CSP */
#if defined(_WIN32) || defined(_WIN32_WCE)
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0400
#endif
#ifdef _WIN32_WCE
#define UNDER_CE
#define ARM
#endif
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <wincrypt.h>
static unsigned long _rng_win32(unsigned char *buf, unsigned long len,
void (*callback)(void))
{
HCRYPTPROV hProv = 0;
LTC_UNUSED_PARAM(callback);
if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
(CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
!CryptAcquireContext (&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET))
return 0;
if (CryptGenRandom(hProv, len, buf) == TRUE) {
CryptReleaseContext(hProv, 0);
return len;
} else {
CryptReleaseContext(hProv, 0);
return 0;
}
}
#endif /* WIN32 */
/**
Read the system RNG
@param out Destination
@param outlen Length desired (octets)
@param callback Pointer to void function to act as "callback" when RNG is slow. This can be NULL
@return Number of octets read
*/
unsigned long rng_get_bytes(unsigned char *out, unsigned long outlen,
void (*callback)(void))
{
unsigned long x;
LTC_ARGCHK(out != NULL);
#ifdef LTC_PRNG_ENABLE_LTC_RNG
if (ltc_rng) {
x = ltc_rng(out, outlen, callback);
if (x != 0) {
return x;
}
}
#endif
#if defined(_WIN32) || defined(_WIN32_WCE)
x = _rng_win32(out, outlen, callback); if (x != 0) { return x; }
#elif defined(LTC_DEVRANDOM)
x = _rng_nix(out, outlen, callback); if (x != 0) { return x; }
#endif
#ifdef ANSI_RNG
x = _rng_ansic(out, outlen, callback); if (x != 0) { return x; }
#endif
return 0;
}
#endif /* #ifdef LTC_RNG_GET_BYTES */
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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