diff --git a/oauth3.core.js b/oauth3.core.js
index e5a7dbb..d3d1dfe 100644
--- a/oauth3.core.js
+++ b/oauth3.core.js
@@ -38,9 +38,10 @@
     , encodeUrlSafe: function (b64) {
         // for directive passing in .well-known/oauth3
         // Base64 to URL-safe Base64
+        b64 = OAUTH3._base64.btoa(b64);
         b64 = b64.replace(/\+/g, '-').replace(/\//g, '_');
         b64 = b64.replace(/=+/g, '');
-        return OAUTH3._base64.btoa(b64);
+        return b64;
       }
     }
   , uri: {
@@ -510,7 +511,7 @@
         }
       , _getCached: function (providerUri) {
           providerUri = OAUTH3.uri.normalize(providerUri);
-          return OAUTH3.hooks.session._sessions[providerUri];
+          return OAUTH3.hooks.session._cache[providerUri];
         }
       , set: function (providerUri, newSession) {
           if (!providerUri) {
@@ -518,8 +519,8 @@
             throw new Error("providerUri is not set");
           }
           providerUri = OAUTH3.uri.normalize(providerUri);
-          if (!OAUTH3.hooks.session._sessions) { OAUTH3.hooks.session._sessions = {}; }
-          OAUTH3.hooks.session._sessions[providerUri] = newSession;
+          if (!OAUTH3.hooks.session._cache) { OAUTH3.hooks.session._cache = {}; }
+          OAUTH3.hooks.session._cache[providerUri] = newSession;
           return OAUTH3.PromiseA.resolve(OAUTH3.hooks.session._set(providerUri, newSession));
         }
       , get: function (providerUri) {
@@ -527,10 +528,13 @@
           if (!providerUri) {
             throw new Error("providerUri is not set");
           }
-          if (!OAUTH3.hooks.session._sessions) { OAUTH3.hooks.session._sessions = {}; }
+          if (!OAUTH3.hooks.session._cache) { OAUTH3.hooks.session._cache = {}; }
 
-          return OAUTH3.PromiseA.resolve(OAUTH3.hooks.session._sessions[providerUri]
-            || OAUTH3.hooks.session._get(providerUri) || null);
+          return OAUTH3.PromiseA.resolve(OAUTH3.hooks.session._cache[providerUri]
+            || OAUTH3.hooks.session._get(providerUri)).then(function (session) {
+            OAUTH3.hooks.session._cache[providerUri] = session;
+            return session;
+          });
         }
       , _get: function (providerUri) {
           console.warn('[Warn] Please implement OAUTH3.hooks.session._get = function (providerUri) { return PromiseA<savedSession>; }');
@@ -1036,8 +1040,16 @@
           });
         });
       }
+    , checkSession: function () {
+        return OAUTH3.hooks.session.get(this._providerUri);
+      }
     , login: function (opts) {
         var me = this;
+        if (me.session()) {
+          me._session = true;
+          return OAUTH3.PromiseA.resolve(me.session());
+        }
+
         opts = opts || {};
         opts.client_uri = me._clientUri;
 
@@ -1047,7 +1059,7 @@
         });
       }
     , session: function () {
-        return JSON.parse(JSON.stringify(OAUTH3.hooks.session._getCached(this._providerUri)));
+        return JSON.parse(JSON.stringify(OAUTH3.hooks.session._getCached(this._providerUri) || {}));
       }
     , request: function (preq, opts) {
         opts = opts || {};
diff --git a/oauth3.implicit.js b/oauth3.implicit.js
deleted file mode 120000
index 9131872..0000000
--- a/oauth3.implicit.js
+++ /dev/null
@@ -1 +0,0 @@
-oauth3.core.js
\ No newline at end of file