added hook to create new session with stored key

oauth3.issuer.js

@@ -283,7 +283,7 @@ OAUTH3.urls.publishKey = function (directive, opts) {
   return {
     method: jwkDir.method || opts.method || 'POST'
   , url: url
-  , data: opts.public_key
+  , data: opts.public_key || opts.publicKey
   , session: opts.session
   };
 };
@@ -605,6 +605,48 @@ OAUTH3.hooks.keyPairs = {
     return OAUTH3.PromiseA.resolve(OAUTH3._hooks.keyPairs.clear());
   }
 };
+OAUTH3.hooks.session.get = function (providerUri, id) {
+  OAUTH3.hooks._checkStorage('sessions', 'get');
+  var sessProm = OAUTH3.PromiseA.resolve(OAUTH3._hooks.sessions.get(providerUri, id));
+  if (providerUri !== OAUTH3.clientUri(window.location)) {
+    return sessProm;
+  }
+
+  return sessProm.then(function (session) {
+    if (session && OAUTH3.jwt.freshness(session.token) === 'fresh') {
+      return session;
+    }
+
+    return OAUTH3.hooks.keyPairs.all().then(function (keyPairs) {
+      var pair;
+      if (id) {
+        pair = keyPairs[id];
+      } else if (Object.keys(keyPairs).length === 1) {
+        id = Object.keys(keyPairs)[0];
+        pair = keyPairs[id];
+      } else if (Object.keys(keyPairs).length > 1) {
+        console.error("too many users, don't know which key to use");
+      }
+      if (!pair) {
+        return null;
+      }
+
+      var payload = {
+        iss: providerUri
+      , aud: providerUri
+      , azp: providerUri
+      , sub: pair.sub || id
+      , scope: ''
+      };
+      return OAUTH3.jwt.sign(payload, pair.privateKey).then(function (token) {
+        return OAUTH3.hooks.session.refresh(
+          { provider_uri: providerUri, client_uri: providerUri || providerUri }
+        , { access_token: token }
+        );
+      });
+    });
+  });
+};
 
 OAUTH3._defaultStorage.grants = {
   prefix: 'grants-'