/** XTS Encryption
@param pt [in] Plaintext
@param ptlen Length of plaintext (and ciphertext)
@param ct [out] Ciphertext
@param tweak [in] The 128--bit encryption tweak (e.g. sector number)
@param xts The XTS structure
Returns CRYPT_OK upon success
*/
int xts_encrypt(
const uint8_t *pt, unsigned long ptlen,
uint8_t *ct,
const uint8_t *tweak,
symmetric_xts *xts)
{
aesedp_encrypt_ctx *encrypt_ctx = &xts->key1.encrypt;
uint8_t PP[16], CC[16], T[16];
uint32_t i, m, mo, lim;
uint32_t err;
/* check inputs */
if((pt == 0) || (ct == 0)|| (tweak == 0) || (xts == 0)) return 1;
/* get number of blocks */
m = ptlen >> 4;
mo = ptlen & 15;
/* must have at least one full block */
if (m == 0) {
return CRYPT_INVALID_ARG;
}
/* encrypt the tweak */
if ((err = aes_encrypt(tweak, T, &xts->key2.encrypt)) != 0) {
return CRYPT_INVALID_KEYSIZE;
}
/* for i = 0 to m-2 do */
if (mo == 0) {
lim = m;
} else {
lim = m - 1;
}
for (i = 0; i < lim; i++) {
err = tweak_crypt(pt, ct, T, encrypt_ctx);
ct += 16;
pt += 16;
}
/* if ptlen not divide 16 then */
if (mo > 0) {
/* CC = tweak encrypt block m-1 */
if ((err = tweak_crypt(pt, CC, T, encrypt_ctx)) != 0) {
return err;
}
/* Cm = first ptlen % 16 bytes of CC */
for (i = 0; i < mo; i++) {
PP[i] = pt[16+i];
ct[16+i] = CC[i];
}
for (; i < 16; i++) {
PP[i] = CC[i];
}
/* Cm-1 = Tweak encrypt PP */
if ((err = tweak_crypt(PP, ct, T, encrypt_ctx)) != 0) {
return err;
}
}
return err;
}
/** XTS Encryption
@param pt [in] Plaintext
@param ptlen Length of plaintext (and ciphertext)
@param ct [out] Ciphertext
@param tweak [in] The 128--bit encryption tweak (e.g. sector number)
@param xts The XTS structure
Returns CRYPT_OK upon success
*/
int xts_encrypt(const unsigned char *pt, unsigned long ptlen, unsigned char *ct, unsigned char *tweak,
symmetric_xts *xts)
{
unsigned char PP[16], CC[16], T[16];
unsigned long i, m, mo, lim;
int err;
/* check inputs */
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(tweak != NULL);
LTC_ARGCHK(xts != NULL);
/* check if valid */
if ((err = cipher_is_valid(xts->cipher)) != CRYPT_OK) {
return err;
}
/* get number of blocks */
m = ptlen >> 4;
mo = ptlen & 15;
/* must have at least one full block */
if (m == 0) {
return CRYPT_INVALID_ARG;
}
if (mo == 0) {
lim = m;
} else {
lim = m - 1;
}
if (cipher_descriptor[xts->cipher].accel_xts_encrypt && lim > 0) {
/* use accelerated encryption for whole blocks */
if ((err = cipher_descriptor[xts->cipher].accel_xts_encrypt(pt, ct, lim, tweak, &xts->key1, &xts->key2) !=
CRYPT_OK)) {
return err;
}
ct += lim * 16;
pt += lim * 16;
/* tweak is encrypted on output */
XMEMCPY(T, tweak, sizeof(T));
} else {
/* encrypt the tweak */
if ((err = cipher_descriptor[xts->cipher].ecb_encrypt(tweak, T, &xts->key2)) != CRYPT_OK) {
return err;
}
for (i = 0; i < lim; i++) {
err = tweak_crypt(pt, ct, T, xts);
ct += 16;
pt += 16;
}
}
/* if ptlen not divide 16 then */
if (mo > 0) {
/* CC = tweak encrypt block m-1 */
if ((err = tweak_crypt(pt, CC, T, xts)) != CRYPT_OK) {
return err;
}
/* Cm = first ptlen % 16 bytes of CC */
for (i = 0; i < mo; i++) {
PP[i] = pt[16 + i];
ct[16 + i] = CC[i];
}
for (; i < 16; i++) {
PP[i] = CC[i];
}
/* Cm-1 = Tweak encrypt PP */
if ((err = tweak_crypt(PP, ct, T, xts)) != CRYPT_OK) {
return err;
}
}
/* Decrypt the tweak back */
if ((err = cipher_descriptor[xts->cipher].ecb_decrypt(T, tweak, &xts->key2)) != CRYPT_OK) {
return err;
}
return err;
}
/** XTS Encryption
@param pt [in] Plaintext
@param ptlen Length of plaintext (and ciphertext)
@param ct [out] Ciphertext
@param tweak [in] The 128--bit encryption tweak (e.g. sector number)
@param xts The XTS structure
Returns CRYPT_OK upon success
*/
int xts_encrypt(
void *context,
ltc_gladman_set_key MethodSetKey,
ltc_gladman_encrypt MethodEncrypt,
int Key1Length, // In bits
FREEOTFEBYTE* Key1,
int Key2Length, // In bits
FREEOTFEBYTE* Key2,
const unsigned char *pt, unsigned long ptlen,
unsigned char *ct,
const unsigned char *tweak
//ltc-orig symmetric_xts *xts
)
{
unsigned char PP[16], CC[16], T[16];
unsigned long i, m, mo, lim;
int err;
/* check inputs */
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(tweak != NULL);
//ltc-orig LTC_ARGCHK(xts != NULL);
//ltc-orig /* check if valid */
//ltc-orig if ((err = cipher_is_valid(xts->cipher)) != CRYPT_OK) {
//ltc-orig return err;
//ltc-orig }
/* get number of blocks */
m = ptlen >> 4;
mo = ptlen & 15;
/* must have at least one full block */
if (m == 0) {
return CRYPT_INVALID_ARG;
}
/* encrypt the tweak */
//ltc-orig if ((err = cipher_descriptor[xts->cipher].ecb_encrypt(tweak, T, &xts->key2)) != CRYPT_OK) {
//ltc-orig return err;
//ltc-orig }
MethodSetKey(context, Key2, Key2Length, enc);
MethodEncrypt(context, tweak, T);
/* for i = 0 to m-2 do */
if (mo == 0) {
lim = m;
} else {
lim = m - 1;
}
MethodSetKey(context, Key1, Key1Length, enc);
for (i = 0; i < lim; i++) {
//ltc-orig err = tweak_crypt(pt, ct, T, xts);
err = tweak_crypt(context, MethodEncrypt, pt, ct, T);
ct += 16;
pt += 16;
}
/* if ptlen not divide 16 then */
if (mo > 0) {
/* CC = tweak encrypt block m-1 */
//ltc-orig if ((err = tweak_crypt(pt, CC, T, xts)) != CRYPT_OK) {
if ((err = tweak_crypt(context, MethodEncrypt, pt, CC, T)) != CRYPT_OK) {
return err;
}
/* Cm = first ptlen % 16 bytes of CC */
for (i = 0; i < mo; i++) {
PP[i] = pt[16+i];
ct[16+i] = CC[i];
}
for (; i < 16; i++) {
PP[i] = CC[i];
}
/* Cm-1 = Tweak encrypt PP */
//ltc-orig if ((err = tweak_crypt(PP, ct, T, xts)) != CRYPT_OK) {
if ((err = tweak_crypt(context, MethodEncrypt, PP, ct, T)) != CRYPT_OK) {
return err;
}
}
return err;
}
