diff --git a/src/conf.c b/src/conf.c
index 099b77da..0bbee092 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -400,6 +400,24 @@ bool read_connection_config(connection_t *c) {
 	return x;
 }
 
+bool append_connection_config(const connection_t *c, const char *key, const char *value) {
+	char *fname;
+	xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
+
+	FILE *fp = fopen(fname, "a");
+
+	if(!fp) {
+		logger(LOG_ERR, "Cannot open config file %s: %s", fname, strerror(errno));
+	} else {
+		fprintf(fp, "\n# The following line was automatically added by tinc\n%s = %s\n", key, value);
+		fclose(fp);
+	}
+
+	free(fname);
+
+	return fp;
+}
+
 bool disable_old_keys(FILE *f) {
 	char buf[100];
 	long pos;
diff --git a/src/conf.h b/src/conf.h
index cc57e82b..20fc95e6 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -61,6 +61,7 @@ extern bool read_config_file(splay_tree_t *, const char *);
 extern void read_config_options(splay_tree_t *, const char *);
 extern bool read_server_config(void);
 extern bool read_connection_config(struct connection_t *);
+extern bool append_connection_config(const struct connection_t *, const char *, const char *);
 extern FILE *ask_and_open(const char *, const char *, const char *);
 extern bool is_safe_path(const char *);
 extern bool disable_old_keys(FILE *);
diff --git a/src/openssl/ecdsa.c b/src/openssl/ecdsa.c
index a4f0f30d..43464d88 100644
--- a/src/openssl/ecdsa.c
+++ b/src/openssl/ecdsa.c
@@ -26,8 +26,8 @@
 #include "ecdsa.h"
 #include "utils.h"
 
-// Set ECDSA keys
-
+// Get and set ECDSA keys
+//
 bool ecdsa_set_base64_public_key(ecdsa_t *ecdsa, const char *p) {
 	*ecdsa = EC_KEY_new_by_curve_name(NID_secp521r1);
 
@@ -44,6 +44,18 @@ bool ecdsa_set_base64_public_key(ecdsa_t *ecdsa, const char *p) {
 	return true;
 }
 
+char *ecdsa_get_base64_public_key(ecdsa_t *ecdsa) {
+	unsigned char *pubkey = NULL;
+	int len = i2o_ECPublicKey(*ecdsa, &pubkey);
+
+	char *base64 = malloc(len * 4 / 3 + 5);
+	b64encode(pubkey, base64, len);
+
+	free(pubkey);
+
+	return base64;
+}
+
 // Read PEM ECDSA keys
 
 bool ecdsa_read_pem_public_key(ecdsa_t *ecdsa, FILE *fp) {
diff --git a/src/openssl/ecdsa.h b/src/openssl/ecdsa.h
index cc0e7b02..04f9eb98 100644
--- a/src/openssl/ecdsa.h
+++ b/src/openssl/ecdsa.h
@@ -25,6 +25,7 @@
 typedef EC_KEY *ecdsa_t;
 
 extern bool ecdsa_set_base64_public_key(ecdsa_t *ecdsa, const char *p);
+extern char *ecdsa_get_base64_public_key(ecdsa_t *ecdsa);
 extern bool ecdsa_read_pem_public_key(ecdsa_t *ecdsa, FILE *fp);
 extern bool ecdsa_read_pem_private_key(ecdsa_t *ecdsa, FILE *fp);
 extern size_t ecdsa_size(ecdsa_t *ecdsa);
diff --git a/src/protocol_auth.c b/src/protocol_auth.c
index d38814c6..70062f3f 100644
--- a/src/protocol_auth.c
+++ b/src/protocol_auth.c
@@ -43,8 +43,12 @@
 bool send_id(connection_t *c) {
 	gettimeofday(&c->start, NULL);
 
+	int minor = myself->connection->protocol_minor;
+	if(c->config_tree && !read_ecdsa_public_key(c))
+		minor = 1;
+
 	return send_request(c, "%d %s %d.%d", ID, myself->connection->name,
-						myself->connection->protocol_major, myself->connection->protocol_minor);
+						myself->connection->protocol_major, minor);
 }
 
 bool id_h(connection_t *c, char *request) {
@@ -110,6 +114,13 @@ bool id_h(connection_t *c, char *request) {
 				   c->name);
 			return false;
 		}
+
+		if(c->protocol_minor >= 2)
+			if(!read_ecdsa_public_key(c))
+				return false;
+	} else {
+		if(!ecdsa_active(&c->ecdsa))
+			c->protocol_minor = 1;
 	}
 
 	c->allow_request = METAKEY;
@@ -121,9 +132,6 @@ bool id_h(connection_t *c, char *request) {
 }
 
 bool send_metakey_ec(connection_t *c) {
-	if(!read_ecdsa_public_key(c))
-		return false;
-
 	logger(LOG_DEBUG, "Sending ECDH metakey to %s", c->name);
 
 	size_t siglen = ecdsa_size(&myself->connection->ecdsa);
@@ -149,11 +157,6 @@ bool send_metakey_ec(connection_t *c) {
 }
 
 bool send_metakey(connection_t *c) {
-	size_t len = rsa_size(&c->rsa);
-	char key[len];
-	char enckey[len];
-	char hexkey[2 * len + 1];
-
 	if(!read_rsa_public_key(c))
 		return false;
 
@@ -163,6 +166,11 @@ bool send_metakey(connection_t *c) {
 	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);
@@ -451,7 +459,24 @@ bool chal_reply_h(connection_t *c, char *request) {
 	return send_ack(c);
 }
 
+static bool send_upgrade(connection_t *c) {
+	/* Special case when protocol_minor is 1: the other end is ECDSA capable,
+	 * but doesn't know our key yet. So send it now. */
+
+	char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
+
+	if(!pubkey)
+		return false;
+
+	bool result = send_request(c, "%d %s", ACK, pubkey);
+	free(pubkey);
+	return result;
+}
+
 bool send_ack(connection_t *c) {
+	if(c->protocol_minor == 1)
+		return send_upgrade(c);
+
 	/* ACK message contains rest of the information the other end needs
 	   to create node_t and edge_t structures. */
 
@@ -516,7 +541,29 @@ static void send_everything(connection_t *c) {
 	}
 }
 
+static bool upgrade_h(connection_t *c, char *request) {
+	char pubkey[MAX_STRING_SIZE];
+
+	if(sscanf(request, "%*d " MAX_STRING, pubkey) != 1) {
+		logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name, c->hostname);
+		return false;
+	}
+
+	if(ecdsa_active(&c->ecdsa) || read_ecdsa_public_key(c)) {
+		logger(LOG_INFO, "Already have ECDSA public key from %s (%s), not upgrading.", c->name, c->hostname);
+		return false;
+	}
+
+	logger(LOG_INFO, "Got ECDSA public key from %s (%s), upgrading!", c->name, c->hostname);
+	append_connection_config(c, "ECDSAPublicKey", pubkey);
+	c->allow_request = TERMREQ;
+	return send_termreq(c);
+}
+
 bool ack_h(connection_t *c, char *request) {
+	if(c->protocol_minor == 1)
+		return upgrade_h(c, request);
+
 	char hisport[MAX_STRING_SIZE];
 	char *hisaddress;
 	int weight, mtu;