-/*

- Derived from source code of TrueCrypt 7.1a, which is

- Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed

- by the TrueCrypt License 3.0.

-

- Modifications and additions to the original source code (contained in this file)

- and all other portions of this file are Copyright (c) 2013-2016 IDRIX

- and are governed by the Apache License 2.0 the full text of which is

- contained in the file License.txt included in VeraCrypt binary and source

- code distribution packages.

-*/

-

-#include "Tcdefs.h"

-#include "Wipe.h"

-

-

-static BOOL Wipe1PseudoRandom (int pass, byte *buffer, size_t size)

-{

- return FALSE;

-}

-

-

-// Fill buffer with wipe patterns defined in "National Industrial Security Program Operating Manual", US DoD 5220.22-M.

-// Return: FALSE = buffer must be filled with random data

-

-static BOOL Wipe3Dod5220 (int pass, byte *buffer, size_t size)

-{

- byte wipeChar;

-

- switch (pass)

- {

- case 1:

- wipeChar = 0;

- break;

-

- case 2:

- wipeChar = 0xff;

- break;

-

- default:

- return FALSE;

- }

-

- memset (buffer, wipeChar, size);

- return TRUE;

-}

-

-

-static BOOL Wipe7Dod5220 (int pass, byte randChars[TC_WIPE_RAND_CHAR_COUNT], byte *buffer, size_t size)

-{

- byte wipeChar;

-

- switch (pass)

- {

- case 1:

- wipeChar = randChars[0];

- break;

-

- case 2:

- wipeChar = ~randChars[0];

- break;

-

- case 4:

- wipeChar = randChars[1];

- break;

-

- case 5:

- wipeChar = randChars[2];

- break;

-

- case 6:

- wipeChar = ~randChars[2];

- break;

-

- default:

- return FALSE;

- }

-

- memset (buffer, wipeChar, size);

- return TRUE;

-}

-

-

-// Fill the buffer with wipe patterns defined in the paper "Secure Deletion of Data from Magnetic and Solid-State Memory" by Peter Gutmann.

-// Return: FALSE = buffer must be filled with random data

-

-static BOOL Wipe35Gutmann (int pass, byte *buffer, size_t size)

-{

- byte wipePat3[] = { 0x92, 0x49, 0x24 };

- int wipePat3Pos;

- size_t i;

-

- switch (pass)

- {

- case 5:

- memset (buffer, 0x55, size);

- break;

-

- case 6:

- memset (buffer, 0xaa, size);

- break;

-

- case 7:

- case 26:

- case 29:

- wipePat3Pos = 0;

- goto wipe3;

-

- case 8:

- case 27:

- case 30:

- wipePat3Pos = 1;

- goto wipe3;

-

- case 9:

- case 28:

- case 31:

- wipePat3Pos = 2;

- goto wipe3;

-

-wipe3:

- if (pass >= 29)

- {

- wipePat3[0] = ~wipePat3[0];

- wipePat3[1] = ~wipePat3[1];

- wipePat3[2] = ~wipePat3[2];

- }

-

- for (i = 0; i < size; ++i)

- {

- buffer[i] = wipePat3[wipePat3Pos++ % 3];

- }

- break;

-

- default:

- if (pass >= 10 && pass <= 25)

- memset (buffer, (pass - 10) * 0x11, size);

- else

- return FALSE;

- }

-

- return TRUE;

-}

-

-

-int GetWipePassCount (WipeAlgorithmId algorithm)

-{

- switch (algorithm)

- {

- case TC_WIPE_1_RAND:

- return 1;

-

- case TC_WIPE_3_DOD_5220:

- return 3;

-

- case TC_WIPE_7_DOD_5220:

- return 7;

-

- case TC_WIPE_35_GUTMANN:

- return 35;

-

- case TC_WIPE_256:

- return 256;

- }

-

- return -1; // Prevent compiler warnings

-}

-

-

-BOOL WipeBuffer (WipeAlgorithmId algorithm, byte randChars[TC_WIPE_RAND_CHAR_COUNT], int pass, byte *buffer, size_t size)

-{

- switch (algorithm)

- {

- case TC_WIPE_1_RAND:

- case TC_WIPE_256:

- return Wipe1PseudoRandom (pass, buffer, size);

-

- case TC_WIPE_3_DOD_5220:

- return Wipe3Dod5220 (pass, buffer, size);

-

- case TC_WIPE_7_DOD_5220:

- return Wipe7Dod5220 (pass, randChars, buffer, size);

-

- case TC_WIPE_35_GUTMANN:

- return Wipe35Gutmann (pass, buffer, size);

-

- /* we will never reach here because all calls to WipeBuffer are preceeded

- * by a call to GetWipePassCount that already checks the same algorithm

- * parameters and in case of unsupported value an error is returned before

- * calling WipeBuffer

- */

- /*

- default:

- TC_THROW_FATAL_EXCEPTION;*/

- }

-

- return FALSE; // Prevent compiler warnings

-}