// =========================================================================
// Decryption function
// Note: PlaintextLength must be set to the size of the PlaintextData buffer on
// entry; on exit, this will be set to the size of the buffer used.
NTSTATUS
ImpCypherDecryptSectorData(
IN GUID* CypherGUID,
IN LARGE_INTEGER SectorID, // Indexed from zero
IN int SectorSize, // In bytes
IN int KeyLength, // In bits
IN FREEOTFEBYTE* Key,
IN char* KeyASCII, // ASCII representation of "Key"
IN int IVLength, // In bits
IN FREEOTFEBYTE* IV,
IN int CyphertextLength, // In bytes
IN FREEOTFEBYTE* CyphertextData,
OUT FREEOTFEBYTE* PlaintextData
)
{
NTSTATUS status = STATUS_SUCCESS;
// libtomcrypt can't handle NULL IVs in CBC mode - it ASSERTs that IV != NULL
char ltcNullIV[FREEOTFE_MAX_CYPHER_BLOCKSIZE];
int cipher;
symmetric_CBC *cbc;
int errnum;
DEBUGOUTCYPHERIMPL(DEBUGLEV_ENTER, (TEXT("ImpCypherDecryptData\n")));
if (!(
(IsEqualGUID(&CIPHER_GUID_CAST5, CypherGUID))
))
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unsupported cipher GUID passed in.\n")));
status = STATUS_INVALID_PARAMETER;
}
// libtomcrypt can't handle NULL IVs in CBC mode - it ASSERTs that IV != NULL
if ( (IVLength == 0) || (IV == NULL) )
{
FREEOTFE_MEMZERO(<cNullIV, sizeof(ltcNullIV));
IV = (char*)<cNullIV;
}
cbc = FREEOTFE_MEMALLOC(sizeof(symmetric_CBC));
FREEOTFE_MEMZERO(cbc, sizeof(symmetric_CBC));
if NT_SUCCESS(status)
{
status = InitLTCCypher(&cipher);
}
if NT_SUCCESS(status)
{
// Start a CBC session
if ((errnum = cbc_start(
cipher,
IV,
Key,
(KeyLength/8),
0,
cbc
)) != CRYPT_OK)
{
status = STATUS_UNSUCCESSFUL;
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to start CBC session (errnum: %d)\n"), errnum));
}
else
{
if ((errnum = cbc_decrypt(
CyphertextData,
PlaintextData,
CyphertextLength,
cbc
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to encrypt/decrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
cbc_done(cbc);
}
}
SecZeroMemory(cbc, sizeof(symmetric_CBC));
FREEOTFE_FREE(cbc);
DEBUGOUTCYPHERIMPL(DEBUGLEV_EXIT, (TEXT("ImpCypherDecryptData\n")));
return status;
}
// =========================================================================
// Encrypt/Decrypt function
// Note: PlaintextLength must be set to the size of the PlaintextData buffer on
// entry; on exit, this will be set to the size of the buffer used.
NTSTATUS
ImpCypherCryptData(
IN GUID* CypherGUID,
IN LARGE_INTEGER SectorID,
IN int SectorSize, // In bytes
IN int KeyLength, // In bits
IN FREEOTFEBYTE* Key,
IN char* KeyASCII, // ASCII representation of "Key"
IN int IVLength, // In bits
IN FREEOTFEBYTE* IV,
IN BOOLEAN encryptNotDecrypt, // TRUE = encrypt; FALSE = decrypt
IN int InLength, // In bytes
IN FREEOTFEBYTE* InData,
OUT FREEOTFEBYTE* OutData
)
{
NTSTATUS status = STATUS_SUCCESS;
// libtomcrypt can't handle NULL IVs in CBC mode - it ASSERTs that IV != NULL
char ltcNullIV[FREEOTFE_MAX_CYPHER_BLOCKSIZE];
int cipher;
symmetric_CBC *cbc;
symmetric_LRW *lrw;
symmetric_xts *xts;
int errnum;
CYPHER_MODE mode;
int keySizeUnderlying;
LARGE_INTEGER blockID64;
INTEGER_128 blockID128;
DEBUGOUTCYPHERIMPL(DEBUGLEV_ENTER, (TEXT("ImpCypherDecryptData\n")));
status = DetermineCypherDetails(
CypherGUID,
&keySizeUnderlying,
&mode
);
// libtomcrypt can't handle NULL IVs in CBC mode - it ASSERTs that IV != NULL
if ( (IVLength == 0) || (IV == NULL) )
{
FREEOTFE_MEMZERO(<cNullIV, sizeof(ltcNullIV));
IV = (char*)<cNullIV;
}
// Sanity check on key supplied
if NT_SUCCESS(status)
{
switch (mode)
{
case CYPHER_MODE_CBC:
{
if (KeyLength != keySizeUnderlying)
{
status = STATUS_INVALID_PARAMETER;
}
break;
}
case CYPHER_MODE_XTS:
{
if (KeyLength != (2 * keySizeUnderlying))
{
status = STATUS_INVALID_PARAMETER;
}
break;
}
case CYPHER_MODE_LRW:
{
if (KeyLength != (keySizeUnderlying + (twofish_desc.block_length * 8)))
{
status = STATUS_INVALID_PARAMETER;
}
break;
}
}
}
if NT_SUCCESS(status)
{
status = InitLTCCypher(&cipher);
}
if NT_SUCCESS(status)
{
switch (mode)
{
case CYPHER_MODE_CBC:
{
cbc = FREEOTFE_MEMALLOC(sizeof(symmetric_CBC));
FREEOTFE_MEMZERO(cbc, sizeof(symmetric_CBC));
// Start a CBC session
if ((errnum = cbc_start(
cipher,
IV,
Key,
(keySizeUnderlying/8),
0,
cbc
)) != CRYPT_OK)
{
status = STATUS_UNSUCCESSFUL;
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to start CBC session (errnum: %d)\n"), errnum));
}
else
{
if (encryptNotDecrypt)
{
if ((errnum = cbc_encrypt(
InData,
OutData,
InLength,
cbc
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to encrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
}
else
{
if ((errnum = cbc_decrypt(
InData,
OutData,
InLength,
cbc
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to decrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
}
cbc_done(cbc);
}
SecZeroMemory(cbc, sizeof(symmetric_CBC));
FREEOTFE_FREE(cbc);
break;
}
case CYPHER_MODE_LRW:
{
lrw = FREEOTFE_MEMALLOC(sizeof(symmetric_LRW));
FREEOTFE_MEMZERO(lrw, sizeof(symmetric_LRW));
// Generate index in correct format
// LRW uses:
// *) The block index (i.e. the number of 128 bit blocks)
// *) The first block has block index 1 - not 0!
// *) Bigendian format
// Note: LTC increments this itself as it processes each block
SectorIDToBlockIdx_64Bit(SectorID, SectorSize, &blockID64);
LARGE_INTEGER__To__INTEGER_128_BigEndian(
blockID64,
blockID128
);
IV = blockID128;
// Start a LRW session
if ((errnum = lrw_start(
cipher,
IV,
Key,
(keySizeUnderlying/8),
// 128 bits tweak key begins after the
// cypher key
(Key + (keySizeUnderlying/8)),
0,
lrw
)) != CRYPT_OK)
{
status = STATUS_UNSUCCESSFUL;
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to start LRW session (errnum: %d)\n"), errnum));
}
else
{
if (encryptNotDecrypt)
{
if ((errnum = lrw_encrypt(
InData,
OutData,
InLength,
lrw
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to encrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
}
else
{
if ((errnum = lrw_decrypt(
InData,
OutData,
InLength,
lrw
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to decrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
}
lrw_done(lrw);
}
SecZeroMemory(lrw, sizeof(symmetric_LRW));
FREEOTFE_FREE(lrw);
break;
}
case CYPHER_MODE_XTS:
{
xts = FREEOTFE_MEMALLOC(sizeof(symmetric_xts));
FREEOTFE_MEMZERO(xts, sizeof(symmetric_xts));
// Generate index in correct format
// XTS uses:
// *) The sector index (i.e. the number of N-bit sectors)
// *) The first sector is sector 0
// *) Littleendian format
LARGE_INTEGER__To__INTEGER_128_LittleEndian(
SectorID,
blockID128
);
// Start an XTS session
if ((errnum = xts_start(
cipher,
Key,
&(Key[keySizeUnderlying/8]),
(keySizeUnderlying/8),
0,
xts
)) != CRYPT_OK)
{
status = STATUS_UNSUCCESSFUL;
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to start XTS session (errnum: %d)\n"), errnum));
}
else
{
if (encryptNotDecrypt)
{
if ((errnum = xts_encrypt(
InData,
InLength,
OutData,
blockID128,
xts
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to encrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
}
else
{
if ((errnum = xts_decrypt(
InData,
InLength,
OutData,
blockID128,
xts
)) != CRYPT_OK)
{
DEBUGOUTCYPHERIMPL(DEBUGLEV_ERROR, (TEXT("Unable to decrypt block (errnum: %d)\n"), errnum));
status = STATUS_UNSUCCESSFUL;
}
}
xts_done(xts);
}
SecZeroMemory(xts, sizeof(symmetric_xts));
FREEOTFE_FREE(xts);
break;
}
}
}
DEBUGOUTCYPHERIMPL(DEBUGLEV_EXIT, (TEXT("ImpCypherDecryptData\n")));
return status;
}
