337 lines
8.2 KiB
C
337 lines
8.2 KiB
C
/**
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* \file
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* <!--
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* This file is part of BeRTOS.
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*
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* Bertos 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 2 of the License, or
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* (at your option) any later version.
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*
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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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*
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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, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2007 Develer S.r.l. (http://www.develer.com/)
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*
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* -->
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*
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* \brief MD2 Message-Digest algorithm.
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*
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* The MD2 algorithm work with a constant array of 256 permutationt
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* defined in RFC1319. If you don't want to use a standard array of
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* permutatione you can use a md2_perm() function that generate an
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* array of 256 "casual" permutation. To swich from a standard array
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* to md2_perm function you must chanche CONFIG_MD2_STD_PERM defined in
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* appconfig.h.
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* If you need to store array in program memory you must define
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* a macro _PROGMEM (for more info see cpu/pgm.h).
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*
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*
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* \author Daniele Basile <asterix@develer.com>
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*/
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#include "md2.h"
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#include <string.h> //memset(), memcpy();
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#include <cfg/compiler.h>
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#include <cfg/debug.h> //ASSERT()
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#include <cfg/macros.h> //MIN(), countof(), ROTR();
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#include <cpu/pgm.h>
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#if CONFIG_MD2_STD_PERM
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/*
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* Official array of 256 byte pemutation contructed from digits of pi, defined
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* in the RFC 1319.
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*/
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static const uint8_t PROGMEM md2_perm[256] =
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{
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41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
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19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
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76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
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138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
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245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
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148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
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39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
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181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
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150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
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112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
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96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
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85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
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234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
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129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
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8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
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203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
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166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
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31, 26, 219, 153, 141, 51, 159, 17, 131, 20
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};
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#define MD2_PERM(x) pgm_read8(&md2_perm[x])
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#else
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/**
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* Md2_perm() function generate an array of 256 "casual" permutation.
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*/
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/**
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* Costant define for computing an array of 256 "casual" permutation.
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* \{
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*/
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#define K1 5
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#define K2 3
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#define R 2
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#define X 172
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/*\}*/
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static uint8_t md2_perm(uint8_t i)
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{
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i = i * K1;
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i = ROTR(i, R);
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i ^= X;
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i = i * K2;
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return i;
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}
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#define MD2_PERM(x) md2_perm(x)
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#endif
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/**
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* Pad function. Put len_pad unsigned char in
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* input block.
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*/
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static void md2_pad(void *_block, size_t len_pad)
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{
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uint8_t *block;
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block = (uint8_t *)_block;
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ASSERT(len_pad <= CONFIG_MD2_BLOCK_LEN);
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/*
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* Fill input block with len_pad char.
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*/
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memset(block, len_pad, len_pad);
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}
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static void md2_compute(void *_state, void *_checksum, void *_block)
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{
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int i = 0;
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uint16_t t = 0;
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uint8_t compute_array[COMPUTE_ARRAY_LEN];
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uint8_t *state;
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uint8_t *checksum;
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uint8_t *block;
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state = (uint8_t *)_state;
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checksum = (uint8_t *)_checksum;
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block = (uint8_t *)_block;
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/*
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* Copy state and checksum context in compute array.
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*/
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memcpy(compute_array, state, CONFIG_MD2_BLOCK_LEN);
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memcpy(compute_array + CONFIG_MD2_BLOCK_LEN, block, CONFIG_MD2_BLOCK_LEN);
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/*
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* Fill compute array with state XOR block
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*/
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for(i = 0; i < CONFIG_MD2_BLOCK_LEN; i++)
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compute_array[i + (CONFIG_MD2_BLOCK_LEN * 2)] = state[i] ^ block[i];
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/*
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* Encryt block.
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*/
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for(i = 0; i < NUM_COMPUTE_ROUNDS; i++)
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{
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for(int j = 0; j < COMPUTE_ARRAY_LEN; j++)
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{
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compute_array[j] ^= MD2_PERM(t);
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t = compute_array[j];
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}
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t = (t + i) & 0xff; //modulo 256.
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}
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/*
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* Update checksum.
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*/
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t = checksum[CONFIG_MD2_BLOCK_LEN - 1];
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for(i = 0; i < CONFIG_MD2_BLOCK_LEN; i++)
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{
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checksum[i] ^= MD2_PERM(block[i] ^ t);
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t = checksum[i];
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}
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/*
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* Update state and clean compute array.
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*/
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memcpy(state, compute_array, CONFIG_MD2_BLOCK_LEN);
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memset(compute_array, 0, sizeof(compute_array));
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}
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/**
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* Algorithm initialization.
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*
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* \param context empty context.
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*/
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void md2_init(Md2Context *context)
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{
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memset(context, 0, sizeof(Md2Context));
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}
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/**
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* Update block.
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*/
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void md2_update(Md2Context *context, const void *_block_in, size_t block_len)
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{
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const uint8_t *block_in;
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size_t cpy_len;
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block_in = (const uint8_t *)_block_in;
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while(block_len > 0)
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{
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/*
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* Choose a number of block that fill input context buffer.
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*/
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cpy_len = MIN(block_len, CONFIG_MD2_BLOCK_LEN - context->counter);
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/*
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* Copy in the buffer input block.
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*/
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memcpy(&context->buffer[context->counter], block_in, cpy_len);
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/*
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* Update a context counter, input block length and remaning
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* context buffer block lenght.
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*/
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context->counter += cpy_len;
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block_len -= cpy_len;
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block_in += cpy_len;
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/*
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* If buffer is full, compute it.
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*/
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if (context->counter >= CONFIG_MD2_BLOCK_LEN)
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{
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md2_compute(context->state, context->checksum, context->buffer);
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context->counter = 0;
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}
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}
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}
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/**
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* Ends an MD2 message digest operation.
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* This fuction take an context and return a pointer
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* to context state.
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*
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* \param context in input.
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* \return a pointer to context state (message digest).
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*/
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uint8_t *md2_end(Md2Context *context)
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{
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uint8_t buf[CONFIG_MD2_BLOCK_LEN];
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/*
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* Fill remaning empty context buffer.
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*/
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md2_pad(buf, CONFIG_MD2_BLOCK_LEN - context->counter);
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/*
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* Update context buffer and compute it.
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*/
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md2_update(context, buf, CONFIG_MD2_BLOCK_LEN - context->counter);
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/*
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* Add context checksum to message input.
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*/
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md2_update(context, context->checksum, CONFIG_MD2_BLOCK_LEN);
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return context->state; //return a pointer to message digest.
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}
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/**
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* MD2 test fuction.
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* This function test MD2 algorithm with a standard string specified
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* in RFC 1319.
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*
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* \note This test work with official array of 256 byte pemutation
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* contructed from digits of pi, defined in the RFC 1319.
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*
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*/
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bool md2_test(void)
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{
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Md2Context context;
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const char *test[] =
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{
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"",
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"message digest",
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"abcdefghijklmnopqrstuvwxyz",
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"12345678901234567890123456789012345678901234567890123456789012345678901234567890"
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};
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const char *result[] = {
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"\x83\x50\xe5\xa3\xe2\x4c\x15\x3d\xf2\x27\x5c\x9f\x80\x69\x27\x73",
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"\xab\x4f\x49\x6b\xfb\x2a\x53\x0b\x21\x9f\xf3\x30\x31\xfe\x06\xb0",
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"\x4e\x8d\xdf\xf3\x65\x02\x92\xab\x5a\x41\x08\xc3\xaa\x47\x94\x0b",
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"\xd5\x97\x6f\x79\xd8\x3d\x3a\x0d\xc9\x80\x6c\x3c\x66\xf3\xef\xd8",
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};
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for (size_t i = 0; i < countof(test); i++)
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{
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md2_init(&context);
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md2_update(&context, test[i], strlen(test[i]));
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if(memcmp(result[i], md2_end(&context), MD2_DIGEST_LEN))
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return false;
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}
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return true;
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}
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#if 0
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#include <stdio.h>
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int main(int argc, char * argv[])
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{
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if(md2_test())
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printf("MD2 algorithm work well!\n");
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else
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printf("MD2 algorithm doesn't work well.\n");
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}
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#endif
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