Initial

frontend/js-encryption/decrypt.js

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+async function decrypt(ciphertext, password) {
+	const pwUtf8 = new TextEncoder().encode(password);
+	const pwHash = await crypto.subtle.digest('SHA-256', pwUtf8);
+	const ctUtf8 = new Uint8Array(Array.from(atob(ciphertext)).map(x => x.charCodeAt(0)));
+	const alg = { name: 'AES-GCM', iv: ctUtf8.slice(0,12) };
+	const key = await crypto.subtle.importKey('raw', pwHash, alg, false, ['decrypt']);
+	try {
+		const buf = await crypto.subtle.decrypt(alg, key, ctUtf8.slice(12));
+		return new TextDecoder().decode(buf);
+	} catch (e) {
+		throw new Error('Decrypt failed')
+	}
+}

frontend/js-encryption/encrypt.js

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+async function encrypt(plaintext, password) {
+	const pwUtf8 = new TextEncoder().encode(password);
+	const pwHash = await crypto.subtle.digest('SHA-256', pwUtf8);
+	const iv = crypto.getRandomValues(new Uint8Array(12));
+	const alg = { name: 'AES-GCM', iv: iv };
+	const key = await crypto.subtle.importKey('raw', pwHash, alg, false, ['encrypt']);
+	const ptUint8 = new TextEncoder().encode(plaintext);
+	const buf = await crypto.subtle.encrypt(alg, key, ptUint8);
+	const ctStr = Array.from(new Uint8Array(buf)).map(b => String.fromCharCode(b)).join('');
+	return btoa(String.fromCharCode(...iv) + ctStr);
+}