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/*
* Dropbear SSH
*
* Copyright (c) 2002,2003 Matt Johnston
* Copyright (c) 2004 by Mihnea Stoenescu
* 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. */
#include "algo.h"
#include "dbutil.h"
/* This file (algo.c) organises the ciphers which can be used, and is used to
* decide which ciphers/hashes/compression/signing to use during key exchange*/
static int void_cipher(const unsigned char* in, unsigned char* out,
unsigned long len, void *cipher_state) {
if (in != out) {
memmove(out, in, len);
}
return CRYPT_OK;
}
static int void_start(int cipher, const unsigned char *IV,
const unsigned char *key,
int keylen, int num_rounds, void *cipher_state) {
return CRYPT_OK;
}
/* Mappings for ciphers, parameters are
{&cipher_desc, keysize, blocksize} */
/* NOTE: if keysize > 2*SHA1_HASH_SIZE, code such as hashkeys()
needs revisiting */
#ifdef DROPBEAR_AES256
static const struct dropbear_cipher dropbear_aes256 =
{&aes_desc, 32, 16};
#endif
#ifdef DROPBEAR_AES128
static const struct dropbear_cipher dropbear_aes128 =
{&aes_desc, 16, 16};
#endif
#ifdef DROPBEAR_BLOWFISH
static const struct dropbear_cipher dropbear_blowfish =
{&blowfish_desc, 16, 8};
#endif
#ifdef DROPBEAR_TWOFISH256
static const struct dropbear_cipher dropbear_twofish256 =
{&twofish_desc, 32, 16};
#endif
#ifdef DROPBEAR_TWOFISH128
static const struct dropbear_cipher dropbear_twofish128 =
{&twofish_desc, 16, 16};
#endif
#ifdef DROPBEAR_3DES
static const struct dropbear_cipher dropbear_3des =
{&des3_desc, 24, 8};
#endif
/* used to indicate no encryption, as defined in rfc2410 */
const struct dropbear_cipher dropbear_nocipher =
{NULL, 16, 8};
/* A few void* s are required to silence warnings
* about the symmetric_CBC vs symmetric_CTR cipher_state pointer */
const struct dropbear_cipher_mode dropbear_mode_cbc =
{(void*)cbc_start, (void*)cbc_encrypt, (void*)cbc_decrypt};
const struct dropbear_cipher_mode dropbear_mode_none =
{void_start, void_cipher, void_cipher};
#ifdef DROPBEAR_ENABLE_CTR_MODE
/* a wrapper to make ctr_start and cbc_start look the same */
static int dropbear_big_endian_ctr_start(int cipher,
const unsigned char *IV,
const unsigned char *key, int keylen,
int num_rounds, symmetric_CTR *ctr) {
return ctr_start(cipher, IV, key, keylen, num_rounds, CTR_COUNTER_BIG_ENDIAN, ctr);
}
const struct dropbear_cipher_mode dropbear_mode_ctr =
{(void*)dropbear_big_endian_ctr_start, (void*)ctr_encrypt, (void*)ctr_decrypt};
#endif
/* Mapping of ssh hashes to libtomcrypt hashes, including keysize etc.
{&hash_desc, keysize, hashsize} */
#ifdef DROPBEAR_SHA1_HMAC
static const struct dropbear_hash dropbear_sha1 =
{&sha1_desc, 20, 20};
#endif
#ifdef DROPBEAR_SHA1_96_HMAC
static const struct dropbear_hash dropbear_sha1_96 =
{&sha1_desc, 20, 12};
#endif
#ifdef DROPBEAR_MD5_HMAC
static const struct dropbear_hash dropbear_md5 =
{&md5_desc, 16, 16};
#endif
const struct dropbear_hash dropbear_nohash =
{NULL, 16, 0}; /* used initially */
/* The following map ssh names to internal values.
* The ordering here is important for the client - the first mode
* that is also supported by the server will get used. */
algo_type sshciphers[] = {
#ifdef DROPBEAR_ENABLE_CTR_MODE
#ifdef DROPBEAR_AES128
{"aes128-ctr", 0, &dropbear_aes128, 1, &dropbear_mode_ctr},
#endif
#ifdef DROPBEAR_3DES
{"3des-ctr", 0, &dropbear_3des, 1, &dropbear_mode_ctr},
#endif
#ifdef DROPBEAR_AES256
{"aes256-ctr", 0, &dropbear_aes256, 1, &dropbear_mode_ctr},
#endif
#endif /* DROPBEAR_ENABLE_CTR_MODE */
/* CBC modes are always enabled */
#ifdef DROPBEAR_AES128
{"aes128-cbc", 0, &dropbear_aes128, 1, &dropbear_mode_cbc},
#endif
#ifdef DROPBEAR_3DES
{"3des-cbc", 0, &dropbear_3des, 1, &dropbear_mode_cbc},
#endif
#ifdef DROPBEAR_AES256
{"aes256-cbc", 0, &dropbear_aes256, 1, &dropbear_mode_cbc},
#endif
#ifdef DROPBEAR_TWOFISH256
{"twofish256-cbc", 0, &dropbear_twofish256, 1, &dropbear_mode_cbc},
{"twofish-cbc", 0, &dropbear_twofish256, 1, &dropbear_mode_cbc},
#endif
#ifdef DROPBEAR_TWOFISH128
{"twofish128-cbc", 0, &dropbear_twofish128, 1, &dropbear_mode_cbc},
#endif
#ifdef DROPBEAR_BLOWFISH
{"blowfish-cbc", 0, &dropbear_blowfish, 1, &dropbear_mode_cbc},
#endif
{NULL, 0, NULL, 0, NULL}
};
algo_type sshhashes[] = {
#ifdef DROPBEAR_SHA1_96_HMAC
{"hmac-sha1-96", 0, &dropbear_sha1_96, 1, NULL},
#endif
#ifdef DROPBEAR_SHA1_HMAC
{"hmac-sha1", 0, &dropbear_sha1, 1, NULL},
#endif
#ifdef DROPBEAR_MD5_HMAC
{"hmac-md5", 0, &dropbear_md5, 1, NULL},
#endif
{NULL, 0, NULL, 0, NULL}
};
#ifndef DISABLE_ZLIB
algo_type ssh_compress[] = {
{"zlib", DROPBEAR_COMP_ZLIB, NULL, 1, NULL},
{"zlib@openssh.com", DROPBEAR_COMP_ZLIB_DELAY, NULL, 1, NULL},
{"none", DROPBEAR_COMP_NONE, NULL, 1, NULL},
{NULL, 0, NULL, 0, NULL}
};
#endif
algo_type ssh_nocompress[] = {
{"none", DROPBEAR_COMP_NONE, NULL, 1, NULL},
{NULL, 0, NULL, 0, NULL}
};
algo_type sshhostkey[] = {
#ifdef DROPBEAR_RSA
{"ssh-rsa", DROPBEAR_SIGNKEY_RSA, NULL, 1, NULL},
#endif
#ifdef DROPBEAR_DSS
{"ssh-dss", DROPBEAR_SIGNKEY_DSS, NULL, 1, NULL},
#endif
{NULL, 0, NULL, 0, NULL}
};
algo_type sshkex[] = {
{"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1, NULL},
{"diffie-hellman-group14-sha1", DROPBEAR_KEX_DH_GROUP14, NULL, 1, NULL},
{NULL, 0, NULL, 0, NULL}
};
/* Register the compiled in ciphers.
* This should be run before using any of the ciphers/hashes */
void crypto_init() {
const struct ltc_cipher_descriptor *regciphers[] = {
#ifdef DROPBEAR_AES
&aes_desc,
#endif
#ifdef DROPBEAR_BLOWFISH
&blowfish_desc,
#endif
#ifdef DROPBEAR_TWOFISH
&twofish_desc,
#endif
#ifdef DROPBEAR_3DES
&des3_desc,
#endif
NULL
};
const struct ltc_hash_descriptor *reghashes[] = {
/* we need sha1 for hostkey stuff regardless */
&sha1_desc,
#ifdef DROPBEAR_MD5_HMAC
&md5_desc,
#endif
NULL
};
int i;
for (i = 0; regciphers[i] != NULL; i++) {
if (register_cipher(regciphers[i]) == -1) {
dropbear_exit("Error registering crypto");
}
}
for (i = 0; reghashes[i] != NULL; i++) {
if (register_hash(reghashes[i]) == -1) {
dropbear_exit("Error registering crypto");
}
}
}
/* algolen specifies the length of algo, algos is our local list to match
* against.
* Returns DROPBEAR_SUCCESS if we have a match for algo, DROPBEAR_FAILURE
* otherwise */
int have_algo(char* algo, size_t algolen, algo_type algos[]) {
int i;
for (i = 0; algos[i].name != NULL; i++) {
if (strlen(algos[i].name) == algolen
&& (strncmp(algos[i].name, algo, algolen) == 0)) {
return DROPBEAR_SUCCESS;
}
}
return DROPBEAR_FAILURE;
}
/* Output a comma separated list of algorithms to a buffer */
void buf_put_algolist(buffer * buf, algo_type localalgos[]) {
unsigned int i, len;
unsigned int donefirst = 0;
buffer *algolist = NULL;
algolist = buf_new(160);
for (i = 0; localalgos[i].name != NULL; i++) {
if (localalgos[i].usable) {
if (donefirst)
buf_putbyte(algolist, ',');
donefirst = 1;
len = strlen(localalgos[i].name);
buf_putbytes(algolist, localalgos[i].name, len);
}
}
buf_putstring(buf, algolist->data, algolist->len);
buf_free(algolist);
}
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