X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fprotocol_key.c;h=4b2047a79ba978f8c8b5519a9d805d2451622a05;hb=8ace7f3e5771957fbdda8b817fa26951d9d62c28;hp=f52e8961b9b8fb250954c1db6888f48c6299966d;hpb=8dfa072733feab737cabf69f000c70657719826a;p=tinc

diff --git a/src/protocol_key.c b/src/protocol_key.c
index f52e8961..4b2047a7 100644
--- a/src/protocol_key.c
+++ b/src/protocol_key.c
@@ -29,6 +29,7 @@
 #include "net.h"
 #include "netutl.h"
 #include "node.h"
+#include "prf.h"
 #include "protocol.h"
 #include "utils.h"
 #include "xalloc.h"
@@ -278,11 +279,8 @@ bool ans_key_h(connection_t *c, char *request) {
 	from->outcompression = compression;
 
 	/* ECDH or old-style key exchange? */
-	/* TODO: look at SSH and TLS to see how they derive cipher and HMAC keys from shared secret properly */
 	
 	if(!strncmp(key, "ECDH:", 5)) {
-		logger(LOG_DEBUG, "Got ECDH key from %s", from->name);
-
 		keylen = (strlen(key) - 5) / 2;
 
 		if(keylen != ECDH_SIZE) {
@@ -296,7 +294,6 @@ bool ans_key_h(connection_t *c, char *request) {
 		}
 
 		if(!from->ecdh) {
-			logger(LOG_DEBUG, "Woops, we didn't generate our public key yet");
 			from->status.ecdh = true;
 			if(!send_ans_key(from))
 				return false;
@@ -311,31 +308,37 @@ bool ans_key_h(connection_t *c, char *request) {
 
 		/* Update our crypto end */
 
-		char *mykey;
 		size_t mykeylen = cipher_keylength(&myself->incipher);
-		keylen = cipher_keylength(&from->outcipher);
-
-		if(ECDH_SHARED_SIZE < mykeylen) {
-			logger(LOG_ERR, "ECDH key too short for cipher of MYSELF!");
-			return false;
-		}
+		size_t hiskeylen = cipher_keylength(&from->outcipher);
 
+		char *mykey;
+		char *hiskey;
+		char *seed;
+		
 		if(strcmp(myself->name, from->name) < 0) {
-			logger(LOG_DEBUG, "Using left half of shared secret");
-			mykey = shared;
-			memcpy(key, shared + ECDH_SHARED_SIZE - keylen, keylen);
+			mykey = key;
+			hiskey = key + mykeylen * 2;
+			xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name);
 		} else {
-			logger(LOG_DEBUG, "Using right half of shared secret");
-			mykey = shared + ECDH_SHARED_SIZE - mykeylen;
-			memcpy(key, shared, keylen);
+			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);
+		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;
@@ -343,31 +346,22 @@ bool ans_key_h(connection_t *c, char *request) {
 		if(replaywin)
 			memset(from->late, 0, replaywin);
 
-		bin2hex(shared, hex, ECDH_SHARED_SIZE);
-		hex[ECDH_SHARED_SIZE * 2] = 0;
-		logger(LOG_DEBUG, "Shared secret was %s", hex);
-
-		bin2hex(mykey, hex, mykeylen);
-		hex[mykeylen * 2] = 0;
-		logger(LOG_DEBUG, "My part is: %s (%d)", hex, mykeylen);
-
-		bin2hex(key, hex, keylen);
-		hex[keylen * 2] = 0;
-		logger(LOG_DEBUG, "His part is: %s (%d)", hex, keylen);
+		if(strcmp(myself->name, from->name) < 0)
+			memmove(key, key + mykeylen * 2, hiskeylen * 2);
 	} else {
 		keylen = strlen(key) / 2;
 		hex2bin(key, key, keylen);
-	}
 
-	/* Update our copy of the origin's packet key */
+		if(keylen != cipher_keylength(&from->outcipher)) {
+			logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
+			return false;
+		}
 
-	if(keylen != cipher_keylength(&from->outcipher)) {
-		logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
-		return false;
-	}
+		/* Update our copy of the origin's packet key */
 
-	cipher_set_key(&from->outcipher, key, false);
-	digest_set_key(&from->outdigest, key, keylen);
+		cipher_set_key(&from->outcipher, key, false);
+		digest_set_key(&from->outdigest, key, keylen);
+	}
 
 	from->status.validkey = true;
 	from->sent_seqno = 0;