intantiate ephemeral channels with 34 hex characters

www/common/common-hash.js

@@ -76,9 +76,10 @@ define([
         return s.replace(/\/+/g, '/');
     };
 
-    Hash.createChannelId = function () {
-        var id = uint8ArrayToHex(Crypto.Nacl.randomBytes(16));
-        if (id.length !== 32 || /[^a-f0-9]/.test(id)) {
+    Hash.ephemeralChannelLength = 34;
+    Hash.createChannelId = function (ephemeral) {
+        var id = uint8ArrayToHex(Crypto.Nacl.randomBytes(ephemeral? 17: 16));
+        if ([32, 34].indexOf(id.length) === -1 || /[^a-f0-9]/.test(id)) {
             throw new Error('channel ids must consist of 32 hex characters');
         }
         return id;

www/common/sframe-common.js

@@ -197,7 +197,10 @@ define([
     };
     funcs.openCursorChannel = function (saveChanges) {
         var md = JSON.parse(JSON.stringify(ctx.metadataMgr.getMetadata()));
-        var channel = md.cursor || Hash.createChannelId();
+        var channel = md.cursor;
+        if (typeof(channel) !== 'string' || channel.length !== Hash.ephemeralChannelLength) {
+            channel = Hash.createChannelId(true); // true indicates that it's an ephemeral channel
+        }
         if (!md.cursor) {
             md.cursor = channel;
             ctx.metadataMgr.updateMetadata(md);