Mercurial > dropbear
view libtomcrypt/src/prngs/rng_get_bytes.c @ 1343:bbc0a0ee3843
merge main
author | Matt Johnston <matt@ucc.asn.au> |
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date | Thu, 18 May 2017 23:00:12 +0800 |
parents | 0cbe8f6dbf9e |
children | f849a5ca2efc |
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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. * * Tom St Denis, [email protected], http://libtomcrypt.com */ #include "tomcrypt.h" /** @file rng_get_bytes.c portable way to get secure random bits to feed a PRNG (Tom St Denis) */ #ifdef DEVRANDOM /* on *NIX read /dev/random */ static unsigned long rng_nix(unsigned char *buf, unsigned long len, void (*callback)(void)) { #ifdef LTC_NO_FILE return 0; #else FILE *f; unsigned long x; #ifdef TRY_URANDOM_FIRST f = fopen("/dev/urandom", "rb"); if (f == NULL) #endif /* 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 /* DEVRANDOM */ /* on ANSI C platforms with 100 < CLOCKS_PER_SEC < 10000 */ #if defined(CLOCKS_PER_SEC) && !defined(WINCE) #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; if (XCLOCKS_PER_SEC < 100 || XCLOCKS_PER_SEC > 10000) { return 0; } 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; } acc = bits = a = b = 0; return l; } #endif /* Try the Microsoft CSP */ #if defined(WIN32) || defined(WINCE) #define _WIN32_WINNT 0x0400 #ifdef WINCE #define UNDER_CE #define ARM #endif #include <windows.h> #include <wincrypt.h> static unsigned long rng_win32(unsigned char *buf, unsigned long len, void (*callback)(void)) { HCRYPTPROV hProv = 0; 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); #if defined(DEVRANDOM) x = rng_nix(out, outlen, callback); if (x != 0) { return x; } #endif #ifdef WIN32 x = rng_win32(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; } /* $Source: /cvs/libtom/libtomcrypt/src/prngs/rng_get_bytes.c,v $ */ /* $Revision: 1.5 $ */ /* $Date: 2006/12/06 02:01:29 $ */