61 lines
1.5 KiB
C
61 lines
1.5 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
|
|
/* SPDX-License-Identifier: Unlicense */
|
|
|
|
/**
|
|
@file ocb_encrypt.c
|
|
OCB implementation, encrypt data, by Tom St Denis
|
|
*/
|
|
#include "tomcrypt_private.h"
|
|
|
|
#ifdef LTC_OCB_MODE
|
|
|
|
/**
|
|
Encrypt a block of data with OCB.
|
|
@param ocb The OCB state
|
|
@param pt The plaintext (length of the block size of the block cipher)
|
|
@param ct [out] The ciphertext (same size as the pt)
|
|
@return CRYPT_OK if successful
|
|
*/
|
|
int ocb_encrypt(ocb_state *ocb, const unsigned char *pt, unsigned char *ct)
|
|
{
|
|
unsigned char Z[MAXBLOCKSIZE], tmp[MAXBLOCKSIZE];
|
|
int err, x;
|
|
|
|
LTC_ARGCHK(ocb != NULL);
|
|
LTC_ARGCHK(pt != NULL);
|
|
LTC_ARGCHK(ct != NULL);
|
|
if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) {
|
|
return err;
|
|
}
|
|
if (ocb->block_len != cipher_descriptor[ocb->cipher].block_length) {
|
|
return CRYPT_INVALID_ARG;
|
|
}
|
|
|
|
/* compute checksum */
|
|
for (x = 0; x < ocb->block_len; x++) {
|
|
ocb->checksum[x] ^= pt[x];
|
|
}
|
|
|
|
/* Get Z[i] value */
|
|
ocb_shift_xor(ocb, Z);
|
|
|
|
/* xor pt in, encrypt, xor Z out */
|
|
for (x = 0; x < ocb->block_len; x++) {
|
|
tmp[x] = pt[x] ^ Z[x];
|
|
}
|
|
if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, ct, &ocb->key)) != CRYPT_OK) {
|
|
return err;
|
|
}
|
|
for (x = 0; x < ocb->block_len; x++) {
|
|
ct[x] ^= Z[x];
|
|
}
|
|
|
|
#ifdef LTC_CLEAN_STACK
|
|
zeromem(Z, sizeof(Z));
|
|
zeromem(tmp, sizeof(tmp));
|
|
#endif
|
|
return CRYPT_OK;
|
|
}
|
|
|
|
#endif
|