Add frontend, backend and CLI

backend/src/utils/aes-gcm.ts

@@ -0,0 +1,43 @@
+import crypto = require('crypto');
+
+const ALGORITHM = 'aes-256-gcm';
+const BLOCK_SIZE_BYTES = 16;
+
+export default class AesGCM {
+	constructor() {}
+
+	static encrypt(
+		text: string,
+		secret: string
+	): { ciphertext: string; iv: string; tag: string } {
+		const iv = crypto.randomBytes(BLOCK_SIZE_BYTES);
+		const cipher = crypto.createCipheriv(ALGORITHM, secret, iv);
+
+		let ciphertext = cipher.update(text, 'utf8', 'base64');
+		ciphertext += cipher.final('base64');
+		return {
+			ciphertext,
+			iv: iv.toString('base64'),
+			tag: cipher.getAuthTag().toString('base64')
+		};
+	}
+
+	static decrypt(
+		ciphertext: string,
+		iv: string,
+		tag: string,
+		secret: string
+	): string {
+		const decipher = crypto.createDecipheriv(
+			ALGORITHM,
+			secret,
+			Buffer.from(iv, 'base64')
+		);
+		decipher.setAuthTag(Buffer.from(tag, 'base64'));
+
+		let cleartext = decipher.update(ciphertext, 'base64', 'utf8');
+		cleartext += decipher.final('utf8');
+
+		return cleartext;
+	}
+}