+++ /dev/null
-/* LibTomCrypt, modular cryptographic library -- Tom St Denis
- *
- * LibTomCrypt is a library that provides various cryptographic
- * algorithms in a highly modular and flexible manner.
- *
- * The library is free for all purposes without any express
- * guarantee it works.
- */
-
-/**
- @file ocb3_encrypt_last.c
- OCB implementation, internal helper, by Karel Miko
-*/
-#include "tomcrypt.h"
-
-#ifdef LTC_OCB3_MODE
-
-/**
- Finish an OCB (encryption) stream
- @param ocb The OCB state
- @param pt The remaining plaintext
- @param ptlen The length of the plaintext (octets)
- @param ct [out] The output buffer
- @return CRYPT_OK if successful
-*/
-int ocb3_encrypt_last(ocb3_state *ocb, const unsigned char *pt, unsigned long ptlen, unsigned char *ct)
-{
- unsigned char iOffset_star[MAXBLOCKSIZE];
- unsigned char iPad[MAXBLOCKSIZE];
- int err, x, full_blocks, full_blocks_len, last_block_len;
-
- LTC_ARGCHK(ocb != NULL);
- if (pt == NULL) LTC_ARGCHK(ptlen == 0);
- if (ptlen != 0) {
- LTC_ARGCHK(pt != NULL);
- LTC_ARGCHK(ct != NULL);
- }
-
- if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) {
- goto LBL_ERR;
- }
-
- full_blocks = ptlen/ocb->block_len;
- full_blocks_len = full_blocks * ocb->block_len;
- last_block_len = ptlen - full_blocks_len;
-
- /* process full blocks first */
- if (full_blocks>0) {
- if ((err = ocb3_encrypt(ocb, pt, full_blocks_len, ct)) != CRYPT_OK) {
- goto LBL_ERR;
- }
- }
-
- /* at this point: m = ocb->block_index (last block index), Offset_m = ocb->Offset_current */
-
- if (last_block_len>0) {
- /* Offset_* = Offset_m xor L_* */
- ocb3_int_xor_blocks(iOffset_star, ocb->Offset_current, ocb->L_star, ocb->block_len);
-
- /* Pad = ENCIPHER(K, Offset_*) */
- if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(iOffset_star, iPad, &ocb->key)) != CRYPT_OK) {
- goto LBL_ERR;
- }
-
- /* C_* = P_* xor Pad[1..bitlen(P_*)] */
- ocb3_int_xor_blocks(ct+full_blocks_len, pt+full_blocks_len, iPad, last_block_len);
-
- /* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
- ocb3_int_xor_blocks(ocb->checksum, ocb->checksum, pt+full_blocks_len, last_block_len);
- for(x=last_block_len; x<ocb->block_len; x++) {
- if (x == last_block_len)
- ocb->checksum[x] ^= 0x80;
- else
- ocb->checksum[x] ^= 0x00;
- }
-
- /* Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A) */
- /* at this point we calculate only: Tag_part = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) */
- for(x=0; x<ocb->block_len; x++) {
- ocb->tag_part[x] = (ocb->checksum[x] ^ iOffset_star[x]) ^ ocb->L_dollar[x];
- }
- if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->tag_part, ocb->tag_part, &ocb->key)) != CRYPT_OK) {
- goto LBL_ERR;
- }
- }
- else {
- /* Tag = ENCIPHER(K, Checksum_m xor Offset_m xor L_$) xor HASH(K,A) */
- /* at this point we calculate only: Tag_part = ENCIPHER(K, Checksum_m xor Offset_m xor L_$) */
- for(x=0; x<ocb->block_len; x++) {
- ocb->tag_part[x] = (ocb->checksum[x] ^ ocb->Offset_current[x]) ^ ocb->L_dollar[x];
- }
- if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->tag_part, ocb->tag_part, &ocb->key)) != CRYPT_OK) {
- goto LBL_ERR;
- }
- }
-
- err = CRYPT_OK;
-
-LBL_ERR:
-#ifdef LTC_CLEAN_STACK
- zeromem(iOffset_star, MAXBLOCKSIZE);
- zeromem(iPad, MAXBLOCKSIZE);
-#endif
-
- return err;
-}
-
-#endif
-
-/* ref: $Format:%D$ */
-/* git commit: $Format:%H$ */
-/* commit time: $Format:%ai$ */