view bignum.c @ 994:5c5ade336926

Prefer stronger algorithms in algorithm negotiation. Prefer diffie-hellman-group14-sha1 (2048 bit) over diffie-hellman-group1-sha1 (1024 bit). Due to meet-in-the-middle attacks the effective key length of three key 3DES is 112 bits. AES is stronger and faster then 3DES. Prefer to delay the start of compression until after authentication has completed. This avoids exposing compression code to attacks from unauthenticated users. (github pull request #9)
author Fedor Brunner <fedor.brunner@azet.sk>
date Fri, 23 Jan 2015 23:00:25 +0800
parents 7540c0822374
children 2bb4c662d1c2
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/*
 * Dropbear - a SSH2 server
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

/* Contains helper functions for mp_int handling */

#include "includes.h"
#include "dbutil.h"

/* wrapper for mp_init, failing fatally on errors (memory allocation) */
void m_mp_init(mp_int *mp) {

	if (mp_init(mp) != MP_OKAY) {
		dropbear_exit("Mem alloc error");
	}
}

/* simplified duplication of bn_mp_multi's mp_init_multi, but die fatally
 * on error */
void m_mp_init_multi(mp_int *mp, ...) 
{
    mp_int* cur_arg = mp;
    va_list args;

    va_start(args, mp);        /* init args to next argument from caller */
    while (cur_arg != NULL) {
        if (mp_init(cur_arg) != MP_OKAY) {
			dropbear_exit("Mem alloc error");
        }
        cur_arg = va_arg(args, mp_int*);
    }
    va_end(args);
}

void m_mp_alloc_init_multi(mp_int **mp, ...) 
{
    mp_int** cur_arg = mp;
    va_list args;

    va_start(args, mp);        /* init args to next argument from caller */
    while (cur_arg != NULL) {
    	*cur_arg = m_malloc(sizeof(mp_int));
        if (mp_init(*cur_arg) != MP_OKAY) {
			dropbear_exit("Mem alloc error");
        }
        cur_arg = va_arg(args, mp_int**);
    }
    va_end(args);
}

void bytes_to_mp(mp_int *mp, const unsigned char* bytes, unsigned int len) {

	if (mp_read_unsigned_bin(mp, (unsigned char*)bytes, len) != MP_OKAY) {
		dropbear_exit("Mem alloc error");
	}
}

/* hash the ssh representation of the mp_int mp */
void hash_process_mp(const struct ltc_hash_descriptor *hash_desc, 
				hash_state *hs, mp_int *mp) {
	buffer * buf;

	buf = buf_new(512 + 20); /* max buffer is a 4096 bit key, 
								plus header + some leeway*/
	buf_putmpint(buf, mp);
	hash_desc->process(hs, buf->data, buf->len);
	buf_free(buf);
}