src/win32/rand.c

   1 /*****************************************************************************
   2  * rand.c : non-predictible random bytes generator
   3  *****************************************************************************
   4  * Copyright © 2007 Rémi Denis-Courmont
   5  * $Id$
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU Lesser General Public License as published by
   9  * the Free Software Foundation; either version 2.1 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public License
  18  * along with this program; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  20  *****************************************************************************/
  21
  22 #ifdef HAVE_CONFIG_H
  23 # include "config.h"
  24 #endif
  25
  26 #include <vlc_common.h>
  27 #include <vlc_rand.h>
  28
  29 #if VLC_WINSTORE_APP
  30 # define COBJMACROS
  31 # define INITGUID
  32 # include <winstring.h>
  33 # include <roapi.h>
  34 # include <windows.security.cryptography.h>
  35 #else
  36 # include <wincrypt.h>
  37 #endif
  38
  39 void vlc_rand_bytes (void *buf, size_t len)
  40 {
  41     size_t count = len;
  42     uint8_t *p_buf = (uint8_t *)buf;
  43
  44     /* fill buffer with pseudo-random data */
  45     while (count > 0)
  46     {
  47         unsigned int val;
  48         val = rand();
  49         if (count < sizeof (val))
  50         {
  51             memcpy (p_buf, &val, count);
  52             break;
  53         }
  54
  55         memcpy (p_buf, &val, sizeof (val));
  56         count -= sizeof (val);
  57         p_buf += sizeof (val);
  58     }
  59
  60 #if VLC_WINSTORE_APP
  61     static const WCHAR *className = L"Windows.Security.Cryptography.CryptographicBuffer";
  62     const UINT32 clen = wcslen(className);
  63
  64     HSTRING hClassName = NULL;
  65     HSTRING_HEADER header;
  66     HRESULT hr = WindowsCreateStringReference(className, clen, &header, &hClassName);
  67     if (hr) {
  68         WindowsDeleteString(hClassName);
  69         return;
  70     }
  71
  72     ICryptographicBufferStatics *cryptoStatics = NULL;
  73     hr = RoGetActivationFactory(hClassName, &IID_ICryptographicBufferStatics, (void**)&cryptoStatics);
  74     WindowsDeleteString(hClassName);
  75
  76     if (hr)
  77         return;
  78
  79     IBuffer *buffer = NULL;
  80     hr = ICryptographicBufferStatics_GenerateRandom(cryptoStatics, len, &buffer);
  81     if (hr) {
  82         ICryptographicBufferStatics_Release(cryptoStatics);
  83         return;
  84     }
  85
  86     UINT32 olength;
  87     unsigned char *rnd = NULL;
  88     hr = ICryptographicBufferStatics_CopyToByteArray(cryptoStatics, buffer, &olength, (BYTE**)&rnd);
  89     memcpy(buf, rnd, len);
  90
  91     IBuffer_Release(buffer);
  92     ICryptographicBufferStatics_Release(cryptoStatics);
  93 #else
  94     HCRYPTPROV hProv;
  95     /* acquire default encryption context */
  96     if( CryptAcquireContext(
  97         &hProv,                 // Variable to hold returned handle.
  98         NULL,                   // Use default key container.
  99         MS_DEF_PROV,            // Use default CSP.
 100         PROV_RSA_FULL,          // Type of provider to acquire.
 101         CRYPT_VERIFYCONTEXT) )  // Flag values
 102     {
 103         /* fill buffer with pseudo-random data, initial buffer content
 104            is used as auxiliary random seed */
 105         CryptGenRandom(hProv, len, buf);
 106         CryptReleaseContext(hProv, 0);
 107     }
 108 #endif /* VLC_WINSTORE_APP */
 109 }