-int metakey_h(connection_t *c)
-{
- char buffer[MAX_STRING_SIZE];
- int len;
-cp
- if(sscanf(c->buffer, "%*d "MAX_STRING, buffer) != 1)
- {
- syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "METAKEY", c->name, c->hostname);
- return -1;
- }
-cp
- len = RSA_size(myself->connection->rsa_key);
-
- /* Check if the length of the meta key is all right */
-
- if(strlen(buffer) != len*2)
- {
- syslog(LOG_ERR, _("Possible intruder %s (%s): %s"), c->name, c->hostname, "wrong keylength");
- return -1;
- }
-
- /* Allocate buffers for the meta key */
-cp
- if(!c->inkey)
- c->inkey = xmalloc(len);
-
- if(!c->inctx)
- c->inctx = xmalloc(sizeof(*c->inctx));
-
- /* Convert the challenge from hexadecimal back to binary */
-cp
- hex2bin(buffer,buffer,len);
-
- /* Decrypt the meta key */
-cp
- if(RSA_private_decrypt(len, buffer, c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) /* See challenge() */
- {
- syslog(LOG_ERR, _("Error during encryption of meta key for %s (%s)"), c->name, c->hostname);
- return -1;
- }
-
- if(debug_lvl >= DEBUG_SCARY_THINGS)
- {
- bin2hex(c->inkey, buffer, len);
- buffer[len*2] = '\0';
- syslog(LOG_DEBUG, _("Received random meta key (unencrypted): %s"), buffer);
- }
-
- /* All incoming requests will now be encrypted. */
-cp
- EVP_DecryptInit(c->inctx, EVP_bf_cfb(),
- c->inkey + len - EVP_bf_cfb()->key_len,
- c->inkey + len - EVP_bf_cfb()->key_len - EVP_bf_cfb()->iv_len);
-
- c->status.decryptin = 1;
-
- c->allow_request = CHALLENGE;
-cp
- return send_challenge(c);
+bool send_metakey(connection_t *c) {
+ if(!read_rsa_public_key(c))
+ return false;
+
+ if(!cipher_open_blowfish_ofb(&c->outcipher))
+ return false;
+
+ if(!digest_open_sha1(&c->outdigest, -1))
+ return false;
+
+ size_t len = rsa_size(&c->rsa);
+ char key[len];
+ char enckey[len];
+ char hexkey[2 * len + 1];
+
+ /* Create a random key */
+
+ randomize(key, len);
+
+ /* The message we send must be smaller than the modulus of the RSA key.
+ By definition, for a key of k bits, the following formula holds:
+
+ 2^(k-1) <= modulus < 2^(k)
+
+ Where ^ means "to the power of", not "xor".
+ This means that to be sure, we must choose our message < 2^(k-1).
+ This can be done by setting the most significant bit to zero.
+ */
+
+ key[0] &= 0x7F;
+
+ cipher_set_key_from_rsa(&c->outcipher, key, len, true);
+
+ ifdebug(SCARY_THINGS) {
+ bin2hex(key, hexkey, len);
+ hexkey[len * 2] = '\0';
+ logger(LOG_DEBUG, "Generated random meta key (unencrypted): %s", hexkey);
+ }
+
+ /* Encrypt the random data
+
+ We do not use one of the PKCS padding schemes here.
+ This is allowed, because we encrypt a totally random string
+ with a length equal to that of the modulus of the RSA key.
+ */
+
+ if(!rsa_public_encrypt(&c->rsa, key, len, enckey)) {
+ logger(LOG_ERR, "Error during encryption of meta key for %s (%s)", c->name, c->hostname);
+ return false;
+ }
+
+ /* Convert the encrypted random data to a hexadecimal formatted string */
+
+ bin2hex(enckey, hexkey, len);
+ hexkey[len * 2] = '\0';
+
+ /* Send the meta key */
+
+ bool result = send_request(c, "%d %d %d %d %d %s", METAKEY,
+ cipher_get_nid(&c->outcipher),
+ digest_get_nid(&c->outdigest), c->outmaclength,
+ c->outcompression, hexkey);
+
+ c->status.encryptout = true;
+ return result;
+}
+
+static bool metakey_ec_h(connection_t *c, const char *request) {
+ size_t siglen = ecdsa_size(&c->ecdsa);
+ char in[MAX_STRING_SIZE];
+ char key[MAX_STRING_SIZE];
+ char sig[siglen];
+
+ logger(LOG_DEBUG, "Got ECDH metakey from %s", c->name);
+
+ if(sscanf(request, "%*d " MAX_STRING, in) != 1) {
+ logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name, c->hostname);
+ return false;
+ }
+
+ if(strlen(in) != (ECDH_SIZE + siglen) * 2) {
+ logger(LOG_ERR, "Possible intruder %s (%s): %s %d != %d", c->name, c->hostname, "wrong keylength", strlen(in) / 2, (ECDH_SIZE + siglen));
+ return false;
+ }
+
+ hex2bin(in, key, ECDH_SIZE);
+ hex2bin(in + ECDH_SIZE * 2, sig, siglen);
+
+ if(!ecdsa_verify(&c->ecdsa, key, ECDH_SIZE, sig)) {
+ logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "invalid ECDSA signature");
+ return false;
+ }
+
+ char shared[ECDH_SHARED_SIZE * 2 + 1];
+
+ if(!ecdh_compute_shared(&c->ecdh, key, shared))
+ return false;
+
+ /* Update our crypto end */
+
+ if(!cipher_open_by_name(&c->incipher, "aes-256-ofb"))
+ return false;
+ if(!digest_open_by_name(&c->indigest, "sha512", -1))
+ return false;
+ if(!cipher_open_by_name(&c->outcipher, "aes-256-ofb"))
+ return false;
+ if(!digest_open_by_name(&c->outdigest, "sha512", -1))
+ return false;
+
+ size_t mykeylen = cipher_keylength(&c->incipher);
+ size_t hiskeylen = cipher_keylength(&c->outcipher);
+
+ char *mykey;
+ char *hiskey;
+ char *seed;
+
+ if(strcmp(myself->name, c->name) < 0) {
+ mykey = key;
+ hiskey = key + mykeylen * 2;
+ xasprintf(&seed, "tinc TCP key expansion %s %s", myself->name, c->name);
+ } else {
+ mykey = key + hiskeylen * 2;
+ hiskey = key;
+ xasprintf(&seed, "tinc TCP key expansion %s %s", c->name, myself->name);
+ }
+
+ if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
+ return false;
+
+ free(seed);
+
+ bin2hex(shared, shared, ECDH_SHARED_SIZE);
+ shared[ECDH_SHARED_SIZE * 2] = 0;
+ logger(LOG_DEBUG, "Shared secret is %s", shared);
+
+ cipher_set_key(&c->incipher, mykey, true);
+ digest_set_key(&c->indigest, mykey + mykeylen, mykeylen);
+
+ cipher_set_key(&c->outcipher, hiskey, false);
+ digest_set_key(&c->outdigest, hiskey + hiskeylen, hiskeylen);
+
+ c->status.decryptin = true;
+ c->status.encryptout = true;
+ c->allow_request = CHALLENGE;
+
+ return send_challenge(c);