chore: Initial import of FLEX training material

flex-training-flexinale/flexinale-modulith-1-onion/src/main/resources/static/crypto.js

@@ -0,0 +1,92 @@
+// Copyright 2017 Google Inc.
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//      http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+function urlB64ToUint8Array(base64String) {
+  const suffixLength = 4 - base64String.length % 4;
+  const base64 = (base64String + '='.repeat(suffixLength))
+      .replace(/\-/g, '+')
+      .replace(/_/g, '/');
+
+  const raw = window.atob(base64);
+
+  const output = new Uint8Array(raw.length);
+  Array.from(raw).forEach((c, i) => output[i] = c.charCodeAt(0));
+  return output;
+}
+
+function stringToBase64Url(s) {
+  const base64 = window.btoa(s);
+  return base64.replace(/\+/g, '-').replace(/\//g, '_').replace(/\=+$/, '');
+}
+
+function JSONToBase64Url(data) {
+  const s = JSON.stringify(data);
+  return stringToBase64Url(s);
+}
+
+function uint8ArrayToBase64Url(array) {
+  const s = String.fromCodePoint(...array);
+  return stringToBase64Url(s);
+}
+
+/**
+ * @param {string} publicKey public key in URL-safe base64
+ * @param {string} privateKey private key in URL-safe base64
+ * @param {string} endpoint from PushSubscription
+ * @param {string} sender either "mailto:<email>" or a web address
+ * @return {!Promise<string>} the Authorization header
+ */
+function prepareAuthorization(publicKey, privateKey, endpoint, sender) {
+  const origin = new URL(endpoint).origin;
+  const defaultExpiration = Math.floor(Date.now() / 1000) + 43200;  // 12 hours in future
+
+  const header = {
+    typ: 'JWT',
+    alg: 'ES256'
+  };
+  const jwtPayload = {
+    aud: origin,
+    exp: defaultExpiration,
+    sub: sender,
+  };
+
+  // unsignedToken is the URL-safe base64 encoded JSON header and body joined by a dot.
+  const unsignedToken = JSONToBase64Url(header) + '.' + JSONToBase64Url(jwtPayload);
+
+  // Sign unsignedToken using ES256 (SHA-256 over ECDSA). This requires the private key.
+  const publicKeyArray = urlB64ToUint8Array(publicKey);
+  const key = {
+    kty: 'EC',
+    crv: 'P-256',
+    x: uint8ArrayToBase64Url(publicKeyArray.subarray(1, 33)),
+    y: uint8ArrayToBase64Url(publicKeyArray.subarray(33, 65)),
+    d: privateKey,
+  };
+
+  // Perform the signing. importKey returns a Promise, so wait for it to finish.
+  const args = {name: 'ECDSA', namedCurve: 'P-256'};
+  return crypto.subtle.importKey('jwk', key, args, true, ['sign'])
+      .then(key => {
+        return crypto.subtle.sign({
+          name: 'ECDSA',
+          hash: {
+            name: 'SHA-256',
+          },
+        }, key, (new TextEncoder('utf-8')).encode(unsignedToken));
+      })
+      .then(buffer => new Uint8Array(buffer))
+      .then(signature => {
+        return 'WebPush ' + unsignedToken + '.' + uint8ArrayToBase64Url(signature);
+      });
+}