180 lines
4.9 KiB
C
180 lines
4.9 KiB
C
/* cscipher_small_core.c */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
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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 <avr/pgmspace.h>
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#include <stdlib.h>
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#include <string.h>
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#include "memxor.h"
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#include "cscipher.h"
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#define DEBUG 0
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#if DEBUG
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#include "cli.h"
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#endif
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#define ROTL(a) (((a)<<1)|((a)>>7))
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#ifndef SBOX_PROG
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#define SBOX_PROG 0
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#endif
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#if SBOX_PROG
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static const uint8_t fg_table[] PROGMEM = {
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0xfa, 0xd6, 0xb0, 0xb2, 0x7b, 0x5e, 0x71, 0x78,
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0xed, 0xd4, 0xa5, 0xb3, 0xef, 0xdc, 0xe7, 0xf9
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};
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static
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uint8_t p(uint8_t a) {
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a ^= pgm_read_byte(fg_table+(a&0xf))&0xf0;
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a ^= pgm_read_byte(fg_table+(a>>4)) &0x0f;
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a ^= pgm_read_byte(fg_table+(a&0xf))&0xf0;
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return a;
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}
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#define P(a) p(a)
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#else
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#include "cscipher_sbox.h"
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#define P(a) pgm_read_byte(cscipher_sbox+(a))
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#endif
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static const uint8_t round_const[] PROGMEM = {
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0xb7, 0xe1, 0x51, 0x62, 0x8a, 0xed, 0x2a, 0x6a,
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0xbf, 0x71, 0x58, 0x80, 0x9c, 0xf4, 0xf3, 0xc7 };
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static const uint8_t ks_const[] PROGMEM = {
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0x29, 0x0d, 0x61, 0x40, 0x9c, 0xeb, 0x9e, 0x8f,
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0x1f, 0x85, 0x5f, 0x58, 0x5b, 0x01, 0x39, 0x86,
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0x97, 0x2e, 0xd7, 0xd6, 0x35, 0xae, 0x17, 0x16,
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0x21, 0xb6, 0x69, 0x4e, 0xa5, 0x72, 0x87, 0x08,
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0x3c, 0x18, 0xe6, 0xe7, 0xfa, 0xad, 0xb8, 0x89,
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0xb7, 0x00, 0xf7, 0x6f, 0x73, 0x84, 0x11, 0x63,
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0x3f, 0x96, 0x7f, 0x6e, 0xbf, 0x14, 0x9d, 0xac,
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0xa4, 0x0e, 0x7e, 0xf6, 0x20, 0x4a, 0x62, 0x30,
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0x03, 0xc5, 0x4b, 0x5a, 0x46, 0xa3, 0x44, 0x65
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};
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static uint16_t m(uint16_t a)
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{
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uint8_t xl, xr, yl, yr;
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uint16_t ret;
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xr = a >> 8;
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xl = a & 0xff;
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yl = (ROTL(xl) & 0x55) ^ xl ^ xr;
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yr = ROTL(xl) ^ xr;
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ret = (P(yr) << 8) | P(yl);
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return ret;
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}
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static uint16_t m_inv(uint16_t a)
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{
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uint8_t xl, xr;
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xr = P(a >> 8);
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xl = P(a & 0xff);
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xl ^= xr;
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xl ^= (ROTL(xl) & 0xaa);
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xr ^= ROTL(xl);
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return (xr << 8) | xl;
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}
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void cscipher_enc(void *buffer, const cscipher_ctx_t *ctx)
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{
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uint8_t i, j, k;
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uint8_t tmp[8];
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for (i = 0; i < 8; ++i) {
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#if DEBUG
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cli_putstr_P(PSTR("\r\nDBG: round "));
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cli_hexdump(&i, 1);
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cli_putstr_P(PSTR(" buffer:"));
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cli_hexdump(buffer, 8);
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#endif
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for (j = 0; j < 3; ++j) {
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if (j == 0) {
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memxor(buffer, ctx->keys[i], 8);
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} else {
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memxor_P(buffer, round_const + ((j == 1) ? 0 : 8), 8);
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}
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for (k = 0; k < 4; ++k) {
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((uint16_t*) tmp)[k] = m(((uint16_t*) buffer)[k]);
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}
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for (k = 0; k < 4; ++k) {
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((uint8_t*) buffer)[k] = tmp[2 * k];
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((uint8_t*) buffer)[k + 4] = tmp[2 * k + 1];
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}
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}
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}
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memxor(buffer, ctx->keys[8], 8);
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}
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void cscipher_dec(void *buffer, const cscipher_ctx_t *ctx)
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{
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uint8_t i = 7, j, k;
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uint8_t tmp[8];
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memxor(buffer, ctx->keys[8], 8);
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do {
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for (j = 0; j < 3; ++j) {
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for (k = 0; k < 4; ++k) {
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tmp[2 * k] = ((uint8_t*) buffer)[k];
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tmp[2 * k + 1] = ((uint8_t*) buffer)[4 + k];
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}
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for (k = 0; k < 4; ++k) {
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((uint16_t*) buffer)[k] = m_inv(((uint16_t*) tmp)[k]);
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}
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if (j == 2) {
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memxor(buffer, ctx->keys[i], 8);
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} else {
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memxor_P(buffer, round_const + ((j == 1) ? 0 : 8), 8);
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}
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}
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} while (i--);
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}
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void cscipher_init(const void *key, cscipher_ctx_t *ctx)
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{
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uint8_t tmp_key[16], tmp[8];
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uint8_t i, j, k, t = 0;
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memcpy(tmp_key, key, 16);
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for (i = 0; i < 9; ++i) {
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#if DEBUG
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cli_putstr_P(PSTR("\r\nDBG: round "));
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cli_hexdump(&i, 1);
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cli_putstr_P(PSTR(" key state:"));
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cli_hexdump(tmp_key, 16);
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#endif
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memcpy(tmp, tmp_key + (((i & 1) == 0) ? 0 : 8), 8);
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memxor_P(tmp, ks_const + 8 * i, 8);
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for (j = 0; j < 8; ++j) {
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tmp[j] = P(tmp[j]);
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}
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for (j = 0; j < 8; ++j) {
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for (k = 0; k < 8; ++k) {
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t <<= 1;
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t |= tmp[k] >> 7;
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tmp[k] <<= 1;
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}
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tmp_key[j + (((i & 1) == 0) ? 8 : 0)] ^= t;
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}
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memcpy(ctx->keys[i], tmp_key + (((i & 1) == 0) ? 8 : 0), 8);
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}
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}
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