Mercurial > dropbear
diff libtomcrypt/src/prngs/rng_get_bytes.c @ 285:1b9e69c058d2
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> |
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date | Wed, 08 Mar 2006 13:23:58 +0000 |
parents | |
children | 0cbe8f6dbf9e |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libtomcrypt/src/prngs/rng_get_bytes.c Wed Mar 08 13:23:58 2006 +0000 @@ -0,0 +1,144 @@ +/* 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.org + */ +#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) + +#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 */ +#ifdef WIN32 +#define _WIN32_WINNT 0x0400 +#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: 1.3 $ */ +/* $Date: 2005/05/05 14:35:59 $ */