modules/keystore/file_crypt_win32.c

   1 /*****************************************************************************
   2  * file_crypt_win32.c: Crypt using CryptProtectData
   3  *****************************************************************************
   4  * Copyright © 2016 VLC authors, VideoLAN and VideoLabs
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <vlc_keystore.h>
  26 #include "file_crypt.h"
  27
  28 #include <windows.h>
  29 #include <wincrypt.h>
  30
  31 typedef BOOL (WINAPI *ProcessFunc)(DATA_BLOB*, LPCWSTR, DATA_BLOB*, PVOID,
  32                                    CRYPTPROTECT_PROMPTSTRUCT*, DWORD, DATA_BLOB*);
  33
  34 static size_t Process(const uint8_t *p_src, size_t i_src_len, uint8_t **pp_dst, ProcessFunc pf_process)
  35 {
  36     DATA_BLOB input_blob =
  37     {
  38         .cbData = i_src_len,
  39         .pbData = (BYTE*)p_src
  40     };
  41     DATA_BLOB output_blob;
  42
  43     if (pf_process( &input_blob, NULL, NULL, NULL, NULL, CRYPTPROTECT_UI_FORBIDDEN, &output_blob) == FALSE)
  44         return 0;
  45     *pp_dst = malloc(output_blob.cbData);
  46     if( unlikely( *pp_dst == NULL ) )
  47     {
  48         LocalFree( output_blob.pbData );
  49         return 0;
  50     }
  51     memcpy( *pp_dst, output_blob.pbData, output_blob.cbData );
  52     LocalFree( output_blob.pbData );
  53     return output_blob.cbData;
  54 }
  55
  56 static size_t Decrypt( vlc_keystore *p_keystore, void *p_ctx, const uint8_t *p_src,
  57                       size_t i_src_len, uint8_t ** pp_dst )
  58 {
  59     VLC_UNUSED( p_keystore );
  60     VLC_UNUSED( p_ctx );
  61     // Cast the function pointer to avoid an invalid parameter warning, regarding the "description"
  62     // parameter. It's LPCWSTR in the case of CryptProtectData, and LPWSTR* in the case of CryptUnprotect
  63     // Since we pass NULL anyway, we don't care
  64     return Process( p_src, i_src_len, pp_dst, (ProcessFunc)&CryptUnprotectData );
  65 }
  66
  67 static size_t Encrypt( vlc_keystore *p_keystore, void *p_ctx, const uint8_t *p_src,
  68                        size_t i_src_len, uint8_t ** pp_dst )
  69 {
  70     VLC_UNUSED( p_keystore );
  71     VLC_UNUSED( p_ctx );
  72     return Process( p_src, i_src_len, pp_dst, CryptProtectData );
  73 }
  74
  75 int CryptInit(vlc_keystore *p_keystore, struct crypt *p_crypt)
  76 {
  77     VLC_UNUSED( p_keystore );
  78     p_crypt->pf_decrypt = Decrypt;
  79     p_crypt->pf_encrypt = Encrypt;
  80     return VLC_SUCCESS;
  81 }