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* Dropbear - a SSH2 server
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* Copyright (c) 2002,2003 Matt Johnston
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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/* This file (algo.c) organises the ciphers which can be used, and is used to
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* decide which ciphers/hashes/compression/signing to use during key exchange*/
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/* Mappings for ciphers, parameters are
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{&cipher_desc, keysize, blocksize} */
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#ifdef DROPBEAR_AES128_CBC
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const struct dropbear_cipher dropbear_aes128 =
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{&rijndael_desc, 16, 16};
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#ifdef DROPBEAR_BLOWFISH_CBC
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const struct dropbear_cipher dropbear_blowfish =
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{&blowfish_desc, 16, 8};
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#ifdef DROPBEAR_TWOFISH128_CBC
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const struct dropbear_cipher dropbear_twofish128 =
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{&twofish_desc, 16, 16};
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#ifdef DROPBEAR_3DES_CBC
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const struct dropbear_cipher dropbear_3des =
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/* used to indicate no encryption, as defined in rfc2410 */
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const struct dropbear_cipher dropbear_nocipher =
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/* Mapping of ssh hashes to libtomcrypt hashes, including keysize etc.
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{&hash_desc, keysize, hashsize} */
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#ifdef DROPBEAR_SHA1_HMAC
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const struct dropbear_hash dropbear_sha1 =
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#ifdef DROPBEAR_MD5_HMAC
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const struct dropbear_hash dropbear_md5 =
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const struct dropbear_hash dropbear_nohash =
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{NULL, 16, 0}; /* used initially */
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/* The following map ssh names to internal values */
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algo_type sshciphers[] = {
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#ifdef DROPBEAR_AES128_CBC
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{"aes128-cbc", 0, (void*)&dropbear_aes128, 1},
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#ifdef DROPBEAR_BLOWFISH_CBC
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{"blowfish-cbc", 0, (void*)&dropbear_blowfish, 1},
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#ifdef DROPBEAR_TWOFISH128_CBC
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{"twofish-cbc", 0, (void*)&dropbear_twofish128, 1},
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#ifdef DROPBEAR_3DES_CBC
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{"3des-cbc", 0, (void*)&dropbear_3des, 1},
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algo_type sshhashes[] = {
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#ifdef DROPBEAR_SHA1_HMAC
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{"hmac-sha1", 0, (void*)&dropbear_sha1, 1},
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#ifdef DROPBEAR_MD5_HMAC
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{"hmac-md5", 0, (void*)&dropbear_md5, 1},
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algo_type sshcompress[] = {
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{"none", DROPBEAR_COMP_NONE, NULL, 1},
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{"zlib", DROPBEAR_COMP_ZLIB, NULL, 1},
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algo_type sshhostkey[] = {
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{"ssh-rsa", DROPBEAR_SIGNKEY_RSA, NULL, 1},
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{"ssh-dss", DROPBEAR_SIGNKEY_DSS, NULL, 1},
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algo_type sshkex[] = {
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{"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1},
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/* Register the compiled in ciphers.
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* This should be run before using any of the ciphers/hashes */
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const struct _cipher_descriptor *regciphers[] = {
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#ifdef DROPBEAR_AES128_CBC
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#ifdef DROPBEAR_BLOWFISH_CBC
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#ifdef DROPBEAR_TWOFISH128_CBC
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#ifdef DROPBEAR_3DES_CBC
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const struct _hash_descriptor *reghashes[] = {
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/* we need sha1 for hostkey stuff regardless */
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#ifdef DROPBEAR_MD5_HMAC
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for (i = 0; regciphers[i] != NULL; i++) {
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if (register_cipher(regciphers[i]) == -1) {
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dropbear_exit("error registering crypto");
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for (i = 0; reghashes[i] != NULL; i++) {
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if (register_hash(reghashes[i]) == -1) {
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dropbear_exit("error registering crypto");
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/* algolen specifies the length of algo, algos is our local list to match
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* Returns DROPBEAR_SUCCESS if we have a match for algo, DROPBEAR_FAILURE
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int have_algo(char* algo, size_t algolen, algo_type algos[]) {
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for (i = 0; algos[i].name != NULL; i++) {
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if (strlen(algos[i].name) == algolen
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&& (strncmp(algos[i].name, algo, algolen) == 0)) {
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return DROPBEAR_SUCCESS;
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return DROPBEAR_FAILURE;
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/* match the first algorithm in the comma-separated list in buf which is
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* also in localalgos[], or return NULL on failure.
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* (*goodguess) is set to 1 if the preferred client/server algos match,
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* 0 otherwise. This is used for checking if the kexalgo/hostkeyalgos are
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* guessed correctly */
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algo_type * buf_match_algo(buffer* buf, algo_type localalgos[], int *goodguess)
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unsigned char * algolist = NULL;
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unsigned char * remotealgos[MAX_PROPOSED_ALGO];
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unsigned int count, i, j;
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algo_type * ret = NULL;
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/* get the comma-separated list from the buffer ie "algo1,algo2,algo3" */
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algolist = buf_getstring(buf, &len);
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TRACE(("buf_match_algo: %s", algolist));
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if (len > MAX_PROPOSED_ALGO*(MAX_NAME_LEN+1)) {
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goto out; /* just a sanity check, no other use */
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/* remotealgos will contain a list of the strings parsed out */
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/* We will have at least one string (even if it's just "") */
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remotealgos[0] = algolist;
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/* Iterate through, replacing ','s with NULs, to split it into
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for (i = 0; i < len; i++) {
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if (algolist[i] == '\0') {
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/* someone is trying something strange */
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if (algolist[i] == ',') {
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remotealgos[count] = &algolist[i+1];
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if (count == MAX_PROPOSED_ALGO) {
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/* iterate and find the first match */
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for (i = 0; i < count; i++) {
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len = strlen(remotealgos[i]);
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for (j = 0; localalgos[j].name != NULL; j++) {
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if (localalgos[j].usable) {
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if (len == strlen(localalgos[j].name) &&
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strncmp(localalgos[j].name, remotealgos[i], len) == 0) {
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/* set if it was a good guess */
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if (i == 0 && j == 0) {
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/* set the algo to return */
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ret = &localalgos[j];
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/* Output a comma separated list of algorithms to a buffer */
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void buf_put_algolist(buffer * buf, algo_type localalgos[]) {
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unsigned int pos = 0, i, len;
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char str[50]; /* enough for local algo storage */
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for (i = 0; localalgos[i].name != NULL; i++) {
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if (localalgos[i].usable) {
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/* Avoid generating a trailing comma */
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len = strlen(localalgos[i].name);
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memcpy(&str[pos], localalgos[i].name, len);
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TRACE(("buf_put_algolist: %s", str));
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buf_putstring(buf, str, pos);
added
removed
algo.c
