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avr-crypto-lib/gcm/gcm128.c

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/* gcm128.c */
/*
This file is part of the AVR-Crypto-Lib.
Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <memxor.h>
#include <blockcipher_descriptor.h>
#include <bcal-basic.h>
#include <gcm128.h>
#include <stdio.h>
#include <cli.h>
#include <uart.h>
#define DUMP_LEN_LINE(x, len, line) do { \
printf("\n\n (DBG <" __FILE__ " %s " #line ">)" #x ":", __func__); \
cli_hexdump_block((x), (len), 4, 16); \
uart0_flush(); } while (0)
#define DUMP_dummy(x, len, v) DUMP_LEN_LINE(x, len, v)
#define DUMP_LEN(x, len) DUMP_dummy(x, len, __LINE__)
#define DUMP(x) DUMP_LEN(x, sizeof(x))
#define BLOCK_BYTES GCM128_BLOCK_BYTES
#define BLOCK_BITS GCM128_BLOCK_BITS
#define COUNT_BYTES GCM128_COUNT_BYTES
#define COUNT_BITS GCM128_COUNT_BITS
#define POLY_BYTE 0xE1
static uint8_t shift_block_right(void *a)
{
uint8_t c1 = 0, c2;
uint8_t i = BLOCK_BYTES;
uint8_t *p = a;
do {
c2 = *p & 1;
*p = (*p >> 1) | c1;
p++;
c1 = c2 ? 0x80 : 0;
} while (--i);
return c2;
}
static void gmul128(
void *dest,
const void *a,
const void *b)
{
uint8_t c, v[BLOCK_BYTES], t, dummy[BLOCK_BYTES + 1], *(lut[2]);
const uint8_t *x = b;
uint8_t i, j;
memset(dest, 0, BLOCK_BYTES);
memset(dummy, 0, BLOCK_BYTES);
dummy[BLOCK_BYTES] = POLY_BYTE;
memcpy(v, a, BLOCK_BYTES);
lut[0] = dummy;
lut[1] = v;
i = BLOCK_BYTES;
do {
j = 8;
t = *x++;
do {
memxor(dest, lut[t >> 7], BLOCK_BYTES);
t <<= 1;
c = shift_block_right(v);
v[0] ^= dummy[15 + c];
} while (--j);
} while (--i);
}
static void ghash128_init(ghash128_ctx_t *ctx)
{
memset(ctx->tag, 0, 16);
}
static void ghash128_block(
ghash128_ctx_t *ctx,
const void *block)
{
uint8_t tmp[BLOCK_BYTES];
memcpy(tmp, ctx->tag, BLOCK_BYTES);
memxor(tmp, block, BLOCK_BYTES);
gmul128(ctx->tag, tmp, ctx->key);
}
static void inc32(void *a)
{
uint8_t c, *p = a;
c = (p[3]++ == 0);
c &= ((p[2] += c) == 0);
c &= ((p[1] += c) == 0);
p[0] +=c;
}
int8_t gcm128_init(
gcm128_ctx_t *ctx,
const bcdesc_t *cipher,
const void *key,
uint16_t key_length_b,
const void *iv,
uint16_t iv_length_b)
{
uint8_t r;
uint8_t tmp[BLOCK_BYTES];
if (bcal_cipher_getBlocksize_b(cipher) != BLOCK_BITS) {
return -1;
}
if ((r = bcal_cipher_init(cipher, key, key_length_b, &ctx->cipher_ctx))) {
printf_P(PSTR("Error: return code: %"PRId8" key length: %"PRId16" <%s %s %d>\n"), r, key_length_b, __FILE__, __func__, __LINE__);
uart0_flush();
return -2;
}
memset(ctx->ghash_ctx.key, 0, BLOCK_BYTES);
bcal_cipher_enc(ctx->ghash_ctx.key, &ctx->cipher_ctx);
ghash128_init(&ctx->ghash_ctx);
if (iv_length_b == BLOCK_BITS - COUNT_BITS) {
memcpy(ctx->ctr, iv, (BLOCK_BITS - COUNT_BITS) / 8);
memset(&ctx->ctr[BLOCK_BYTES - COUNT_BYTES], 0, COUNT_BYTES - 1);
ctx->ctr[BLOCK_BYTES - 1] = 1;
} else {
uint16_t ctr = iv_length_b / BLOCK_BITS;
while (ctr--)
{
ghash128_block(&ctx->ghash_ctx, iv);
iv = &((uint8_t*)iv)[BLOCK_BYTES];
}
memset(tmp, 0, BLOCK_BYTES);
memcpy(tmp, iv, (iv_length_b % BLOCK_BITS + 7) / 8);
if (iv_length_b & 7) {
tmp[(iv_length_b % BLOCK_BITS) / 8] &= 0xff << (8 - (iv_length_b & 7));
}
ghash128_block(&ctx->ghash_ctx, tmp);
memset(tmp, 0, BLOCK_BYTES);
tmp[BLOCK_BYTES - 2] = iv_length_b >> 8;
tmp[BLOCK_BYTES - 1] = iv_length_b & 0xff;
ghash128_block(&ctx->ghash_ctx, tmp);
memcpy(ctx->ctr, ctx->ghash_ctx.tag, BLOCK_BYTES);
ghash128_init(&ctx->ghash_ctx);
}
memcpy(ctx->j0, &ctx->ctr[BLOCK_BYTES - COUNT_BYTES], COUNT_BYTES);
ctx->length_a = 0;
ctx->length_c = 0;
return 0;
}
void gcm128_add_ad_block(
gcm128_ctx_t *ctx,
const void *block )
{
ghash128_block(&ctx->ghash_ctx, block);
ctx->length_a += BLOCK_BITS;
}
void gcm128_add_ad_final_block(
gcm128_ctx_t *ctx,
const void *block,
uint16_t length_b )
{
uint8_t tmp[BLOCK_BYTES];
while (length_b >= BLOCK_BITS)
{
gcm128_add_ad_block(ctx, block);
length_b -= BLOCK_BITS;
block = &((uint8_t*)block)[BLOCK_BYTES];
}
if (length_b > 0) {
memset(tmp, 0, BLOCK_BYTES);
memcpy(tmp, block, (length_b + 7) / 8);
if (length_b & 7) {
tmp[length_b / 8] &= 0xff << (8 - (length_b & 7));
}
ghash128_block(&ctx->ghash_ctx, tmp);
ctx->length_a += length_b;
}
}
void gcm128_encrypt_block(
gcm128_ctx_t *ctx,
void *dest,
const void *src)
{
uint8_t tmp[BLOCK_BYTES];
inc32(&ctx->ctr[BLOCK_BYTES - COUNT_BYTES]);
memcpy(tmp, ctx->ctr, BLOCK_BYTES);
bcal_cipher_enc(tmp, &ctx->cipher_ctx);
memxor(tmp, src, BLOCK_BYTES);
ghash128_block(&ctx->ghash_ctx, tmp);
ctx->length_c += BLOCK_BITS;
if (dest) {
memcpy(dest, tmp, BLOCK_BYTES);
}
}
void gcm128_encrypt_final_block(
gcm128_ctx_t *ctx,
void *dest,
const void *src,
uint16_t length_b
)
{
uint8_t tmp[BLOCK_BYTES];
while (length_b >= BLOCK_BITS) {
gcm128_encrypt_block(ctx, dest, src);
length_b -= BLOCK_BITS;
if (dest) {
dest = &((uint8_t*)dest)[BLOCK_BYTES];
}
src = &((uint8_t*)src)[BLOCK_BYTES];
}
if (length_b > 0) {
inc32(&ctx->ctr[BLOCK_BYTES - COUNT_BYTES]);
memcpy(tmp, ctx->ctr, BLOCK_BYTES);
bcal_cipher_enc(tmp, &ctx->cipher_ctx);
memxor(tmp, src, BLOCK_BYTES);
memset(&tmp[(length_b + 7) / 8], 0, BLOCK_BYTES - (length_b + 7) / 8);
if (length_b & 7) {
tmp[length_b / 8] &= 0xff << (8 - (length_b & 7));
}
ghash128_block(&ctx->ghash_ctx, tmp);
ctx->length_c += length_b;
if (dest) {
memcpy(dest, tmp, (length_b + 7) / 8);
}
}
}
void gcm128_decrypt_block(
gcm128_ctx_t *ctx,
void *dest,
const void *src)
{
uint8_t tmp[BLOCK_BYTES];
ghash128_block(&ctx->ghash_ctx, src);
inc32(&ctx->ctr[BLOCK_BYTES - COUNT_BYTES]);
memcpy(tmp, ctx->ctr, BLOCK_BYTES);
bcal_cipher_enc(tmp, &ctx->cipher_ctx);
memxor(tmp, src, BLOCK_BYTES);
ctx->length_c += BLOCK_BITS;
if (dest) {
memcpy(dest, tmp, BLOCK_BYTES);
}
}
void gcm128_decrypt_final_block(
gcm128_ctx_t *ctx,
void *dest,
const void *src,
uint16_t length_b)
{
uint8_t tmp[BLOCK_BYTES];
while (length_b > BLOCK_BITS) {
gcm128_decrypt_block(ctx, dest, src);
length_b -= BLOCK_BITS;
if (dest) {
dest = &((uint8_t*)dest)[BLOCK_BYTES];
}
src = &((uint8_t*)src)[BLOCK_BYTES];
}
if (length_b > 0) {
memcpy(tmp, src, (length_b + 7) / 8);
memset(&tmp[(length_b + 7) / 8], 0, BLOCK_BYTES - (length_b + 7) / 8);
if (length_b & 7) {
tmp[length_b / 8] &= 0xff << (8 - (length_b & 7));
}
ghash128_block(&ctx->ghash_ctx, tmp);
inc32(&ctx->ctr[BLOCK_BYTES - COUNT_BYTES]);
memcpy(tmp, ctx->ctr, BLOCK_BYTES);
bcal_cipher_enc(tmp, &ctx->cipher_ctx);
memxor(tmp, src, BLOCK_BYTES);
memset(&tmp[(length_b + 7) / 8], 0, BLOCK_BYTES - (length_b + 7) / 8);
if (length_b & 7) {
tmp[length_b / 8] &= 0xff << (8 - (length_b & 7));
}
ctx->length_c += length_b;
if (dest) {
memcpy(dest, tmp, (length_b + 7) / 8);
}
}
}
void gcm128_finalize(gcm128_ctx_t *ctx, void *tag, uint16_t tag_length_b)
{
uint8_t tmp[BLOCK_BYTES];
memset(tmp, 0, BLOCK_BYTES);
tmp[4] = ctx->length_a >> 24;
tmp[5] = ctx->length_a >> 16;
tmp[6] = ctx->length_a >> 8;
tmp[7] = ctx->length_a;
tmp[12] = ctx->length_c >> 24;
tmp[13] = ctx->length_c >> 16;
tmp[14] = ctx->length_c >> 8;
tmp[15] = ctx->length_c;
ghash128_block(&ctx->ghash_ctx, tmp);
memcpy(tmp, ctx->ctr, BLOCK_BYTES - COUNT_BYTES);
memcpy(&tmp[BLOCK_BYTES - COUNT_BYTES], ctx->j0, COUNT_BYTES);
bcal_cipher_enc(tmp, &ctx->cipher_ctx);
bcal_cipher_free(&ctx->cipher_ctx);
memxor(tmp, ctx->ghash_ctx.tag, BLOCK_BYTES);
if (tag_length_b > BLOCK_BITS) {
tag_length_b = BLOCK_BITS;
}
if (tag_length_b & 7) {
tmp[tag_length_b / 8] &= 0xff << (8 - (tag_length_b & 7));
}
if (tag) {
memcpy(tag, tmp, (tag_length_b + 7) / 8);
}
}
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