1 /* $OpenBSD: getentropy_win.c,v 1.5 2016/08/07 03:27:21 tb Exp $ */ 2 3 /* 4 * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org> 5 * Copyright (c) 2014, Bob Beck <beck@obtuse.com> 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 * 19 * Emulation of getentropy(2) as documented at: 20 * http://man.openbsd.org/getentropy.2 21 */ 22 23 #include <windows.h> 24 #include <errno.h> 25 #include <stdint.h> 26 #include <sys/types.h> 27 #include <wincrypt.h> 28 #include <process.h> 29 30 int getentropy(void *buf, size_t len); 31 32 /* 33 * On Windows, CryptGenRandom is supposed to be a well-seeded 34 * cryptographically strong random number generator. 35 */ 36 int 37 getentropy(void *buf, size_t len) 38 { 39 HCRYPTPROV provider; 40 41 if (len > 256) { 42 errno = EIO; 43 return (-1); 44 } 45 46 if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL, 47 CRYPT_VERIFYCONTEXT) == 0) 48 goto fail; 49 if (CryptGenRandom(provider, len, buf) == 0) { 50 CryptReleaseContext(provider, 0); 51 goto fail; 52 } 53 CryptReleaseContext(provider, 0); 54 return (0); 55 56 fail: 57 errno = EIO; 58 return (-1); 59 } 60