www.pudn.com > truecrypt-4.2-source-code.zip > Cache.c

/* Legal Notice: The source code contained in this file has been derived from 
   the source code of Encryption for the Masses 2.02a, which is Copyright (c) 
   1998-99 Paul Le Roux and which is covered by the 'License Agreement for 
   Encryption for the Masses'. Modifications and additions to that source code 
   contained in this file are Copyright (c) 2004-2006 TrueCrypt Foundation and 
   Copyright (c) 2004 TrueCrypt Team, and are covered by TrueCrypt License 2.0 
   the full text of which is contained in the file License.txt included in 
   TrueCrypt binary and source code distribution archives.  */ 
 
#include "Tcdefs.h" 
 
#ifndef NT4_DRIVER 
#pragma VxD_LOCKED_CODE_SEG 
#pragma VxD_LOCKED_DATA_SEG 
#endif 
 
#include "Crypto.h" 
#include "Fat.h" 
#include "Volumes.h" 
#include "Apidrvr.h" 
#include "Common.h" 
#include "Cache.h" 
 
Password CachedPasswords[CACHE_SIZE]; 
int cacheEmpty = 1; 
static int nPasswordIdx = 0; 
 
int 
VolumeReadHeaderCache (BOOL bCache, char *header, Password *password, PCRYPTO_INFO *retInfo) 
{ 
	int nReturnCode = ERR_PASSWORD_WRONG; 
	int i; 
 
	/* Attempt to recognize volume using mount password */ 
	if (password->Length > 0) 
	{ 
		nReturnCode = VolumeReadHeader (header, password, retInfo); 
 
		/* Save mount passwords back into cache if asked to do so */ 
		if (bCache && (nReturnCode == 0 || nReturnCode == ERR_CIPHER_INIT_WEAK_KEY)) 
		{ 
			for (i = 0; i < CACHE_SIZE; i++) 
			{ 
				if (memcmp (&CachedPasswords[i], password, sizeof (Password)) == 0) 
					break; 
			} 
 
			if (i == CACHE_SIZE) 
			{ 
				/* Store the password */ 
				CachedPasswords[nPasswordIdx] = *password; 
 
				/* Try another slot */ 
				nPasswordIdx = (nPasswordIdx + 1) % CACHE_SIZE; 
 
				cacheEmpty = 0; 
			} 
		} 
	} 
	else if (!cacheEmpty) 
	{ 
		/* Attempt to recognize volume using cached passwords */ 
		for (i = 0; i < CACHE_SIZE; i++) 
		{ 
			if (CachedPasswords[i].Length > 0) 
			{ 
				nReturnCode = VolumeReadHeader (header, &CachedPasswords[i], retInfo); 
 
				if (nReturnCode != ERR_PASSWORD_WRONG) 
					break; 
			} 
		} 
	} 
 
	return nReturnCode; 
} 
 
void 
WipeCache () 
{ 
	burn (CachedPasswords, sizeof (CachedPasswords)); 
	nPasswordIdx = 0; 
	cacheEmpty = 1; 
}