/** Encrypt blocks of data with OCB @param ocb The OCB state @param pt The plaintext (length multiple of the block size of the block cipher) @param ptlen The length of the input (octets) @param ct [out] The ciphertext (same size as the pt) @return CRYPT_OK if successful */ int ocb3_encrypt(ocb3_state *ocb, const unsigned char *pt, unsigned long ptlen, unsigned char *ct) { unsigned char tmp[MAXBLOCKSIZE]; int err, i, full_blocks; unsigned char *pt_b, *ct_b; LTC_ARGCHK(ocb != NULL); if (ptlen == 0) return CRYPT_OK; /* no data, nothing to do */ 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; } if (ptlen % ocb->block_len) { /* ptlen has to bu multiple of block_len */ return CRYPT_INVALID_ARG; } full_blocks = ptlen/ocb->block_len; for(i=0; i<full_blocks; i++) { pt_b = (unsigned char *)pt+i*ocb->block_len; ct_b = (unsigned char *)ct+i*ocb->block_len; /* ocb->Offset_current[] = ocb->Offset_current[] ^ Offset_{ntz(block_index)} */ ocb3_int_xor_blocks(ocb->Offset_current, ocb->Offset_current, ocb->L_[ocb3_int_ntz(ocb->block_index)], ocb->block_len); /* tmp[] = pt[] XOR ocb->Offset_current[] */ ocb3_int_xor_blocks(tmp, pt_b, ocb->Offset_current, ocb->block_len); /* encrypt */ if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) { goto LBL_ERR; } /* ct[] = tmp[] XOR ocb->Offset_current[] */ ocb3_int_xor_blocks(ct_b, tmp, ocb->Offset_current, ocb->block_len); /* ocb->checksum[] = ocb->checksum[] XOR pt[] */ ocb3_int_xor_blocks(ocb->checksum, ocb->checksum, pt_b, ocb->block_len); ocb->block_index++; } err = CRYPT_OK; LBL_ERR: #ifdef LTC_CLEAN_STACK zeromem(tmp, sizeof(tmp)); #endif return err; }
/** Add one block of AAD data (internal function) @param ocb The OCB state @param aad_block [in] AAD data (block_len size) @return CRYPT_OK if successful */ static int _ocb3_int_aad_add_block(ocb3_state *ocb, const unsigned char *aad_block) { unsigned char tmp[MAXBLOCKSIZE]; int err; /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */ ocb3_int_xor_blocks(ocb->aOffset_current, ocb->aOffset_current, ocb->L_[ocb3_int_ntz(ocb->ablock_index)], ocb->block_len); /* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */ ocb3_int_xor_blocks(tmp, aad_block, ocb->aOffset_current, ocb->block_len); if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) { return err; } ocb3_int_xor_blocks(ocb->aSum_current, ocb->aSum_current, tmp, ocb->block_len); ocb->ablock_index++; return CRYPT_OK; }