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87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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/**
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@file ocb3_encrypt.c
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OCB implementation, encrypt data, by Tom St Denis
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*/
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#include "tomcrypt.h"
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#ifdef LTC_OCB3_MODE
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/**
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Encrypt blocks of data with OCB
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@param ocb The OCB state
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@param pt The plaintext (length multiple of the block size of the block cipher)
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@param ptlen The length of the input (octets)
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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 ocb3_encrypt(ocb3_state *ocb, const unsigned char *pt, unsigned long ptlen, unsigned char *ct)
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{
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unsigned char tmp[MAXBLOCKSIZE];
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int err, i, full_blocks;
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unsigned char *pt_b, *ct_b;
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LTC_ARGCHK(ocb != NULL);
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if (ptlen == 0) return CRYPT_OK; /* no data, nothing to do */
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LTC_ARGCHK(pt != NULL);
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LTC_ARGCHK(ct != NULL);
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if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) {
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return err;
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}
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if (ocb->block_len != cipher_descriptor[ocb->cipher].block_length) {
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return CRYPT_INVALID_ARG;
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}
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if (ptlen % ocb->block_len) { /* ptlen has to bu multiple of block_len */
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return CRYPT_INVALID_ARG;
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}
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full_blocks = ptlen/ocb->block_len;
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for(i=0; i<full_blocks; i++) {
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pt_b = (unsigned char *)pt+i*ocb->block_len;
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ct_b = (unsigned char *)ct+i*ocb->block_len;
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/* ocb->Offset_current[] = ocb->Offset_current[] ^ Offset_{ntz(block_index)} */
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ocb3_int_xor_blocks(ocb->Offset_current, ocb->Offset_current, ocb->L_[ocb3_int_ntz(ocb->block_index)], ocb->block_len);
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/* tmp[] = pt[] XOR ocb->Offset_current[] */
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ocb3_int_xor_blocks(tmp, pt_b, ocb->Offset_current, ocb->block_len);
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/* encrypt */
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if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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/* ct[] = tmp[] XOR ocb->Offset_current[] */
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ocb3_int_xor_blocks(ct_b, tmp, ocb->Offset_current, ocb->block_len);
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/* ocb->checksum[] = ocb->checksum[] XOR pt[] */
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ocb3_int_xor_blocks(ocb->checksum, ocb->checksum, pt_b, ocb->block_len);
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ocb->block_index++;
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}
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err = CRYPT_OK;
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LBL_ERR:
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#ifdef LTC_CLEAN_STACK
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zeromem(tmp, sizeof(tmp));
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#endif
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return err;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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