+ /* ECDH or old-style key exchange? */
+
+ if(!strncmp(key, "ECDH:", 5)) {
+ keylen = (strlen(key) - 5) / 2;
+
+ if(keylen != ECDH_SIZE) {
+ logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
+ return false;
+ }
+
+ if(ECDH_SHARED_SIZE < cipher_keylength(&from->outcipher)) {
+ logger(LOG_ERR, "ECDH key too short for cipher of %s!", from->name);
+ return false;
+ }
+
+ if(!from->ecdh) {
+ from->status.ecdh = true;
+ if(!send_ans_key(from))
+ return false;
+ }
+
+ char shared[ECDH_SHARED_SIZE * 2 + 1];
+ char hex[ECDH_SHARED_SIZE * 2 + 1];
+ hex2bin(key + 5, key + 5, keylen);
+
+ if(!ecdh_compute_shared(&from->ecdh, key + 5, shared))
+ return false;
+
+ /* Update our crypto end */
+
+ size_t mykeylen = cipher_keylength(&myself->incipher);
+ size_t hiskeylen = cipher_keylength(&from->outcipher);
+
+ char *mykey;
+ char *hiskey;
+ char *seed;
+
+ if(strcmp(myself->name, from->name) < 0) {
+ mykey = key;
+ hiskey = key + mykeylen * 2;
+ xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name);
+ } else {
+ mykey = key + hiskeylen * 2;
+ hiskey = key;
+ xasprintf(&seed, "tinc UDP key expansion %s %s", from->name, myself->name);
+ }
+
+ if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
+ return false;
+
+ free(seed);
+
+ cipher_open_by_nid(&from->incipher, cipher_get_nid(&myself->incipher));
+ digest_open_by_nid(&from->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
+ from->incompression = myself->incompression;
+
+ cipher_set_key(&from->incipher, mykey, true);
+ digest_set_key(&from->indigest, mykey + mykeylen, mykeylen);
+
+ cipher_set_key(&from->outcipher, hiskey, false);
+ digest_set_key(&from->outdigest, hiskey + hiskeylen, hiskeylen);
+
+ // Reset sequence number and late packet window
+ mykeyused = true;
+ from->received_seqno = 0;
+ if(replaywin)
+ memset(from->late, 0, replaywin);
+
+ if(strcmp(myself->name, from->name) < 0)
+ memmove(key, key + mykeylen * 2, hiskeylen * 2);
+ } else {
+ keylen = strlen(key) / 2;
+ hex2bin(key, key, keylen);
+
+ if(keylen != cipher_keylength(&from->outcipher)) {
+ logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
+ return false;