fat.c

使用visual studio 2005 开发的开源文件、磁盘加密软件。这是6.1a版。加密自己资料的好工具。也是学习的优秀范本。结成了众多加密算法。

/*
 Legal Notice: Some portions of the source code contained in this file were
 derived from the source code of Encryption for the Masses 2.02a, which is
 Copyright (c) 1998-2000 Paul Le Roux and which is governed by the 'License
 Agreement for Encryption for the Masses'. Modifications and additions to
 the original source code (contained in this file) and all other portions of
 this file are Copyright (c) 2003-2008 TrueCrypt Foundation and are governed
 by the TrueCrypt License 2.6 the full text of which is contained in the
 file License.txt included in TrueCrypt binary and source code distribution
 packages. */

#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "Tcdefs.h"

#include "Crypto.h"
#include "Common/Endian.h"
#include "Format.h"
#include "Fat.h"
#include "Progress.h"
#include "Random.h"

void
GetFatParams (fatparams * ft)
{
	unsigned int fatsecs;
	if(ft->cluster_size == 0)	// 'Default' cluster size
	{
		if (ft->num_sectors * 512LL >= 256*BYTES_PER_GB)
			ft->cluster_size = 128;
		else if (ft->num_sectors * 512LL >= 64*BYTES_PER_GB)
			ft->cluster_size = 64;
		else if (ft->num_sectors * 512LL >= 16*BYTES_PER_GB)
			ft->cluster_size = 32;
		else if (ft->num_sectors * 512LL >= 8*BYTES_PER_GB)
			ft->cluster_size = 16;
		else if (ft->num_sectors * 512LL >= 128*BYTES_PER_MB)
			ft->cluster_size = 8;
		else if (ft->num_sectors * 512LL >= 64*BYTES_PER_MB)
			ft->cluster_size = 4;
		else if (ft->num_sectors * 512LL >= 32*BYTES_PER_MB)
			ft->cluster_size = 2;
		else
			ft->cluster_size = 1;
	}

	// Geometry always set to SECTORS/1/1
	ft->secs_track = 1; 
	ft->heads = 1; 

	ft->dir_entries = 512;
	ft->fats = 2;
	ft->media = 0xf8;
	ft->sector_size = SECTOR_SIZE;
	ft->hidden = 0;

	ft->size_root_dir = ft->dir_entries * 32;

	// FAT12
	ft->size_fat = 12;
	ft->reserved = 2;
	fatsecs = ft->num_sectors - (ft->size_root_dir + SECTOR_SIZE - 1) / SECTOR_SIZE - ft->reserved;
	ft->cluster_count = (int) (((__int64) fatsecs * SECTOR_SIZE) / (ft->cluster_size * SECTOR_SIZE + 3));
	ft->fat_length = (((ft->cluster_count * 3 + 1) >> 1) + SECTOR_SIZE - 1) / SECTOR_SIZE;

	if (ft->cluster_count >= 4085) // FAT16
	{
		ft->size_fat = 16;
		ft->reserved = 2;
		fatsecs = ft->num_sectors - (ft->size_root_dir + SECTOR_SIZE - 1) / SECTOR_SIZE - ft->reserved;
		ft->cluster_count = (int) (((__int64) fatsecs * SECTOR_SIZE) / (ft->cluster_size * SECTOR_SIZE + 4));
		ft->fat_length = (ft->cluster_count * 2 + SECTOR_SIZE - 1) / SECTOR_SIZE;
	}
	
	if(ft->cluster_count >= 65525) // FAT32
	{
		ft->size_fat = 32;
		ft->reserved = 32;
		fatsecs = ft->num_sectors - ft->reserved;
		ft->size_root_dir = ft->cluster_size * SECTOR_SIZE;
		ft->cluster_count = (int) (((__int64) fatsecs * SECTOR_SIZE) / (ft->cluster_size * SECTOR_SIZE + 8));
		ft->fat_length = (ft->cluster_count * 4 + SECTOR_SIZE - 1) / SECTOR_SIZE;
	}

	if (ft->num_sectors >= 65536 || ft->size_fat == 32)
	{
		ft->sectors = 0;
		ft->total_sect = ft->num_sectors;
	}
	else
	{
		ft->sectors = ft->num_sectors;
		ft->total_sect = 0;
	}
}

void
PutBoot (fatparams * ft, unsigned char *boot)
{
	int cnt = 0;

	boot[cnt++] = 0xeb;	/* boot jump */
	boot[cnt++] = 0x3c;
	boot[cnt++] = 0x90;
	memcpy (boot + cnt, "MSDOS5.0", 8); /* system id */
	cnt += 8;
	*(__int16 *)(boot + cnt) = LE16(ft->sector_size);	/* bytes per sector */
	cnt += 2;
	boot[cnt++] = (__int8) ft->cluster_size;			/* sectors per cluster */
	*(__int16 *)(boot + cnt) = LE16(ft->reserved);		/* reserved sectors */
	cnt += 2;
	boot[cnt++] = (__int8) ft->fats;					/* 2 fats */

	if(ft->size_fat == 32)
	{
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
	}
	else
	{
		*(__int16 *)(boot + cnt) = LE16(ft->dir_entries);	/* 512 root entries */
		cnt += 2;
	}

	*(__int16 *)(boot + cnt) = LE16(ft->sectors);		/* # sectors */
	cnt += 2;
	boot[cnt++] = (__int8) ft->media;					/* media byte */

	if(ft->size_fat == 32)	
	{
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
	}
	else 
	{ 
		*(__int16 *)(boot + cnt) = LE16(ft->fat_length);	/* fat size */
		cnt += 2;
	}

	*(__int16 *)(boot + cnt) = LE16(ft->secs_track);	/* # sectors per track */
	cnt += 2;
	*(__int16 *)(boot + cnt) = LE16(ft->heads);			/* # heads */
	cnt += 2;
	*(__int32 *)(boot + cnt) = LE32(ft->hidden);		/* # hidden sectors */
	cnt += 4;
	*(__int32 *)(boot + cnt) = LE32(ft->total_sect);	/* # huge sectors */
	cnt += 4;

	if(ft->size_fat == 32)
	{
		*(__int32 *)(boot + cnt) = LE32(ft->fat_length); cnt += 4;	/* fat size 32 */
		boot[cnt++] = 0x00;	/* ExtFlags */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;	/* FSVer */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x02;	/* RootClus */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x01;	/* FSInfo */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x06;	/* BkBootSec */
		boot[cnt++] = 0x00;
		memset(boot+cnt, 0, 12); cnt+=12;	/* Reserved */
	}

	boot[cnt++] = 0x00;	/* drive number */   // FIXED 80 > 00
	boot[cnt++] = 0x00;	/* reserved */
	boot[cnt++] = 0x29;	/* boot sig */

	RandgetBytes (boot + cnt, 4, FALSE);		/* vol id */
	cnt += 4;

	memcpy (boot + cnt, ft->volume_name, 11);	/* vol title */
	cnt += 11;

	switch(ft->size_fat) /* filesystem type */
	{
		case 12: memcpy (boot + cnt, "FAT12   ", 8); break;
		case 16: memcpy (boot + cnt, "FAT16   ", 8); break;
		case 32: memcpy (boot + cnt, "FAT32   ", 8); break;
	}
	cnt += 8;

	memset (boot + cnt, 0, ft->size_fat==32 ? 420:448);	/* boot code */
	cnt += ft->size_fat==32 ? 420:448;
	boot[cnt++] = 0x55;
	boot[cnt++] = 0xaa;	/* boot sig */
}


/* FAT32 FSInfo */
static PutFSInfo (unsigned char *sector, fatparams *ft)
{
	memset (sector, 0, 512);
	sector[3]=0x41; /* LeadSig */
	sector[2]=0x61; 
	sector[1]=0x52; 
	sector[0]=0x52; 
	sector[484+3]=0x61; /* StrucSig */
	sector[484+2]=0x41; 
	sector[484+1]=0x72; 
	sector[484+0]=0x72; 

	// Free cluster count
	*(uint32 *)(sector + 488) = LE32 (ft->cluster_count - ft->size_root_dir / SECTOR_SIZE / ft->cluster_size);

	sector[492+3]=0xff; /* Nxt_Free */
	sector[492+2]=0xff;
	sector[492+1]=0xff;
	sector[492+0]=0xff;
	sector[508+3]=0xaa; /* TrailSig */
	sector[508+2]=0x55;
	sector[508+1]=0x00;
	sector[508+0]=0x00;
}


int
FormatFat (unsigned __int64 startSector, fatparams * ft, void * dev, PCRYPTO_INFO cryptoInfo, BOOL quickFormat)
{
	int write_buf_cnt = 0;
	char sector[SECTOR_SIZE], *write_buf;
	unsigned __int64 nSecNo = startSector;
	int x, n;
	int retVal;
	char temporaryKey[MASTER_KEYDATA_SIZE];

	LARGE_INTEGER startOffset;
	LARGE_INTEGER newOffset;

	// Seek to start sector
	startOffset.QuadPart = startSector * SECTOR_SIZE;
	if (!SetFilePointerEx ((HANDLE) dev, startOffset, &newOffset, FILE_BEGIN)
		|| newOffset.QuadPart != startOffset.QuadPart)
	{
		return ERR_VOL_SEEKING;
	}

	/* Write the data area */

	write_buf = (char *)TCalloc (WRITE_BUF_SIZE);
	memset (sector, 0, sizeof (sector));

	PutBoot (ft, (unsigned char *) sector);
	if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
		cryptoInfo) == FALSE)
		goto fail;

	/* fat32 boot area */
	if (ft->size_fat == 32)				
	{
		/* fsinfo */
		PutFSInfo((unsigned char *) sector, ft);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
			cryptoInfo) == FALSE)
			goto fail;

		/* reserved */
		while (nSecNo - startSector < 6)
		{
			memset (sector, 0, sizeof (sector));
			sector[508+3]=0xaa; /* TrailSig */
			sector[508+2]=0x55;
			if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				cryptoInfo) == FALSE)
				goto fail;
		}
		
		/* bootsector backup */
		memset (sector, 0, sizeof (sector));
		PutBoot (ft, (unsigned char *) sector);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				 cryptoInfo) == FALSE)
			goto fail;

		PutFSInfo((unsigned char *) sector, ft);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
			cryptoInfo) == FALSE)
			goto fail;
	}

	/* reserved */
	while (nSecNo - startSector < (unsigned int)ft->reserved)
	{
		memset (sector, 0, sizeof (sector));
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
			cryptoInfo) == FALSE)
			goto fail;
	}

	/* write fat */
	for (x = 1; x <= ft->fats; x++)
	{
		for (n = 0; n < ft->fat_length; n++)
		{
			memset (sector, 0, SECTOR_SIZE);

			if (n == 0)
			{
				unsigned char fat_sig[12];
				if (ft->size_fat == 32)
				{
					fat_sig[0] = (unsigned char) ft->media;
					fat_sig[1] = fat_sig[2] = 0xff;
					fat_sig[3] = 0x0f;
					fat_sig[4] = fat_sig[5] = fat_sig[6] = 0xff;
					fat_sig[7] = 0x0f;
					fat_sig[8] = fat_sig[9] = fat_sig[10] = 0xff;
					fat_sig[11] = 0x0f;
					memcpy (sector, fat_sig, 12);
				}				
				else if (ft->size_fat == 16)
				{
					fat_sig[0] = (unsigned char) ft->media;
					fat_sig[1] = 0xff;
					fat_sig[2] = 0xff;
					fat_sig[3] = 0xff;
					memcpy (sector, fat_sig, 4);
				}
				else if (ft->size_fat == 12)
				{
					fat_sig[0] = (unsigned char) ft->media;
					fat_sig[1] = 0xff;
					fat_sig[2] = 0xff;
					fat_sig[3] = 0x00;
					memcpy (sector, fat_sig, 4);
				}
			}

			if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				    cryptoInfo) == FALSE)
				goto fail;
		}
	}


	/* write rootdir */
	for (x = 0; x < ft->size_root_dir / SECTOR_SIZE; x++)
	{
		memset (sector, 0, SECTOR_SIZE);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				 cryptoInfo) == FALSE)
			goto fail;

	}

	/* Fill the rest of the data area with random data */

	if(!quickFormat)
	{
		if (!FlushFormatWriteBuffer (dev, write_buf, &write_buf_cnt, &nSecNo, cryptoInfo))
			goto fail;

		/* Generate a random temporary key set to be used for "dummy" encryption that will fill
		the free disk space (data area) with random data.  This is necessary for plausible
		deniability of hidden volumes (and also reduces the amount of predictable plaintext
		within the volume). */

		// Temporary master key
		if (!RandgetBytes (temporaryKey, EAGetKeySize (cryptoInfo->ea), FALSE))
			goto fail;

		// Temporary secondary key (XTS mode)
		if (!RandgetBytes (cryptoInfo->k2, sizeof cryptoInfo->k2, FALSE))		
			goto fail;

		retVal = EAInit (cryptoInfo->ea, temporaryKey, cryptoInfo->ks);
		if (retVal != ERR_SUCCESS)
		{
			burn (temporaryKey, sizeof(temporaryKey));
			return retVal;
		}
		if (!EAInitMode (cryptoInfo))
		{
			burn (temporaryKey, sizeof(temporaryKey));
			return ERR_MODE_INIT_FAILED;
		}

		x = ft->num_sectors - ft->reserved - ft->size_root_dir / SECTOR_SIZE - ft->fat_length * 2;
		while (x--)
		{
			/* Generate random plaintext. Note that reused plaintext blocks are not a concern here
			since XTS mode is designed to hide patterns. Furthermore, patterns in plaintext do 
			occur commonly on media in the "real world", so it might actually be a fatal mistake
			to try to avoid them completely. */

#if RNG_POOL_SIZE < SECTOR_SIZE
#error RNG_POOL_SIZE < SECTOR_SIZE
#endif
			if (!RandpeekBytes (sector, SECTOR_SIZE))
				goto fail;

			// Encrypt the random plaintext and write it to the disk
			if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				cryptoInfo) == FALSE)
				goto fail;
		}
		UpdateProgressBar (nSecNo);
	}
	else
		UpdateProgressBar (ft->num_sectors);

	if (!FlushFormatWriteBuffer (dev, write_buf, &write_buf_cnt, &nSecNo, cryptoInfo))
		goto fail;

	TCfree (write_buf);
	burn (temporaryKey, sizeof(temporaryKey));
	return 0;

fail:

	TCfree (write_buf);
	burn (temporaryKey, sizeof(temporaryKey));
	return ERR_OS_ERROR;
}