120 lines
3.6 KiB
C
120 lines
3.6 KiB
C
/* bca-eax.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2010 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include "bcal-basic.h"
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#include "blockcipher_descriptor.h"
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#include "bcal-cmac.h"
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#include "bcal-ctr.h"
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#include "bcal-eax.h"
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#include "memxor.h"
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uint8_t bcal_eax_init(const bcdesc_t* desc, const void* key, uint16_t keysize_b, bcal_eax_ctx_t* ctx){
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uint8_t r;
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ctx->blocksize_B = (bcal_cipher_getBlocksize_b(desc)+7)/8;
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ctx->nonce = malloc(ctx->blocksize_B);
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if(ctx->nonce==NULL){
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return 0x81;
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}
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r = bcal_cmac_init(desc, key, keysize_b, &(ctx->ctag));
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if(r){
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return r;
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}
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r = bcal_cmac_init(desc, key, keysize_b, &(ctx->htag));
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if(r){
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return (r|0x10);
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}
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r = bcal_cmac_init(desc, key, keysize_b, &(ctx->ntag));
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if(r){
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return (r|0x20);
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}
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r = bcal_ctr_init(desc, key, keysize_b, NULL, &(ctx->cipher));
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if(r){
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return (r|0x30);
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}
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ctx->header_set=0;
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uint8_t tmp[ctx->blocksize_B];
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memset(tmp, 0, ctx->blocksize_B);
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bcal_cmac_nextBlock(&(ctx->ntag), tmp);
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tmp[ctx->blocksize_B-1]=1;
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bcal_cmac_nextBlock(&(ctx->htag), tmp);
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tmp[ctx->blocksize_B-1]=2;
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bcal_cmac_nextBlock(&(ctx->ctag), tmp);
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return 0;
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}
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void bcal_eax_free(bcal_eax_ctx_t* ctx){
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bcal_ctr_free(&(ctx->cipher));
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bcal_cmac_free(&(ctx->ctag));
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bcal_cmac_free(&(ctx->htag));
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bcal_cmac_free(&(ctx->ntag));
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free(ctx->nonce);
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}
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void bcal_eax_loadNonce(const void* nonce, uint16_t length_b, bcal_eax_ctx_t* ctx){
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bcal_cmac_lastBlock(&(ctx->ntag), nonce, length_b);
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bcal_cmac_ctx2mac(ctx->nonce, ctx->blocksize_B*8, &(ctx->ntag));
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bcal_ctr_loadIV(ctx->nonce, &(ctx->cipher));
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}
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void bcal_eax_addNextHeader(const void* header, bcal_eax_ctx_t* ctx){
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bcal_cmac_nextBlock(&(ctx->htag), header);
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}
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void bcal_eax_addLastHeader(const void* header, uint16_t length_b, bcal_eax_ctx_t* ctx){
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bcal_cmac_lastBlock(&(ctx->htag), header, length_b);
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ctx->header_set = 1;
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}
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void bcal_eax_encNextBlock(void* block, bcal_eax_ctx_t* ctx){
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bcal_ctr_encNext(block, &(ctx->cipher));
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bcal_cmac_nextBlock(&(ctx->ctag), block);
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}
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void bcal_eax_encLastBlock(void* block, uint16_t length_b, bcal_eax_ctx_t* ctx){
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bcal_ctr_encMsg(NULL, block, length_b, &(ctx->cipher));
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bcal_cmac_lastBlock(&(ctx->ctag), block, length_b);
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}
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void bcal_eax_decNextBlock(void* block, bcal_eax_ctx_t* ctx){
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bcal_cmac_nextBlock(&(ctx->ctag), block);
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bcal_ctr_decNext(block, &(ctx->cipher));
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}
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void bcal_eax_decLastBlock(void* block, uint16_t length_b, bcal_eax_ctx_t* ctx){
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bcal_cmac_lastBlock(&(ctx->ctag), block, length_b);
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bcal_ctr_decMsg(NULL, block, length_b, &(ctx->cipher));
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}
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void bcal_eax_ctx2tag(void* dest, uint16_t length_b, bcal_eax_ctx_t* ctx){
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uint8_t tmp[ctx->blocksize_B];
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if(ctx->header_set==0){
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bcal_cmac_lastBlock(&(ctx->htag), NULL, 0);
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}
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bcal_cmac_ctx2mac(tmp, ctx->blocksize_B*8, &(ctx->htag));
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memxor(ctx->nonce, tmp, ctx->blocksize_B);
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bcal_cmac_ctx2mac(tmp, ctx->blocksize_B*8, &(ctx->ctag));
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memxor(ctx->nonce, tmp, ctx->blocksize_B);
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memcpy(dest, ctx->nonce, (length_b+7)/8);
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}
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