Saving progress

Author: colecrouter

.gitignore

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+build
+node_modules

package-lock.json

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+{
+  "name": "webpush-notification",
+  "version": "1.0.0",
+  "description": "Minimal library for sending notifications via the browser Push API",
+  "main": "build/pushNotification.js",
+  "dependencies": {
+    "jose": "^5.8.0"
+  },
+  "devDependencies": {
+    "base64url": "^3.0.1",
+    "js-crypto-hkdf": "^1.0.7",
+    "typescript": "^5.5.4"
+  },
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "build": "tsc"
+  },
+  "author": "Cole Crouter",
+  "license": "ISC",
+  "type": "module"
+}

package.json

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+export async function deriveSharedSecret(
+	publicKey: CryptoKey,
+	privateKey: CryptoKey,
+): Promise<CryptoKey> {
+	const sharedSecret = await crypto.subtle.deriveKey(
+		{
+			name: "ECDH",
+			public: publicKey,
+		},
+		privateKey,
+		{
+			name: "AES-GCM",
+			length: 256,
+		},
+		true,
+		["encrypt", "decrypt"],
+	);
+
+	return sharedSecret;
+}

src/crypto/deriveSharedSecret.ts

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+// Uint8Array -> base64url string
+export function encode(input: Uint8Array): string {
+	return btoa(String.fromCharCode(...input));
+}

src/crypto/encode.ts

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+import base64url from "base64url";
+
+const encode = base64url.encode;
+
+export async function encryptPayload(
+	payload: string,
+	sharedSecret: CryptoKey,
+	salt: Uint8Array,
+) {
+	const encodedPayload = new TextEncoder().encode(payload);
+	const encrypted = await crypto.subtle.encrypt(
+		{
+			name: "AES-GCM",
+			iv: salt,
+		},
+		sharedSecret,
+		encodedPayload,
+	);
+	return encode(encrypted);
+}

src/crypto/encryptPayload.ts

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+import { generateKeyPair, exportJWK } from "jose";
+
+export async function generateVapidKeys() {
+	const { publicKey, privateKey } = await generateKeyPair("ES256");
+
+	return { publicKey, privateKey };
+}

src/crypto/generateVapidKeys.ts

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+import { type JWTPayload, SignJWT } from "jose";
+
+export async function signRequest(payload: JWTPayload, privateKey: CryptoKey) {
+	const jwt = await new SignJWT(payload)
+		.setProtectedHeader({ alg: "ES256" })
+		.sign(privateKey);
+	return jwt;
+}