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