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/* $OpenBSD: getentropy_win.c,v 1.5 2016/08/07 03:27:21 tb Exp $ */
/*
* Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
* Copyright (c) 2014, Bob Beck <beck@obtuse.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Emulation of getentropy(2) as documented at:
* http://man.openbsd.org/getentropy.2
*/
#include <windows.h>
#include <errno.h>
#include <stdint.h>
#include <sys/types.h>
#include <wincrypt.h>
#include <process.h>
int getentropy(void *buf, size_t len);
/*
* On Windows, CryptGenRandom is supposed to be a well-seeded
* cryptographically strong random number generator.
*/
int
getentropy(void *buf, size_t len)
{
HCRYPTPROV provider;
if (len > 256) {
errno = EIO;
return (-1);
}
if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT) == 0)
goto fail;
if (CryptGenRandom(provider, len, buf) == 0) {
CryptReleaseContext(provider, 0);
goto fail;
}
CryptReleaseContext(provider, 0);
return (0);
fail:
errno = EIO;
return (-1);
}
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