Message Hashing & Encryption

SHA-256 Hashing

Browser-native Hashing ohne externe Dependencies via Web Crypto API.

export async function hashMessage(message: string): Promise<string> {
  const encoder = new TextEncoder();
  const data = encoder.encode(message);
  const hashBuffer = await crypto.subtle.digest('SHA-256', data);
  const hashArray = Array.from(new Uint8Array(hashBuffer));
  return hashArray.map((b) => b.toString(16).padStart(2, '0')).join('');
}

// Usage
const hash = await hashMessage('Hello World');
// => "a591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e"

AES-GCM Verschlüsselung

End-to-End Encryption für Nachrichten mit Key-Derivation aus Passwort.

export async function deriveKey(password: string, salt: Uint8Array): Promise<CryptoKey> {
  const encoder = new TextEncoder();
  const keyMaterial = await crypto.subtle.importKey(
    'raw',
    encoder.encode(password),
    'PBKDF2',
    false,
    ['deriveKey']
  );

  return crypto.subtle.deriveKey(
    { name: 'PBKDF2', salt, iterations: 100000, hash: 'SHA-256' },
    keyMaterial,
    { name: 'AES-GCM', length: 256 },
    false,
    ['encrypt', 'decrypt']
  );
}

export async function encryptMessage(message: string, password: string): Promise<string> {
  const salt = crypto.getRandomValues(new Uint8Array(16));
  const iv = crypto.getRandomValues(new Uint8Array(12));
  const key = await deriveKey(password, salt);

  const encoder = new TextEncoder();
  const encrypted = await crypto.subtle.encrypt(
    { name: 'AES-GCM', iv },
    key,
    encoder.encode(message)
  );

  // Pack salt + iv + ciphertext into one base64 string
  const packed = new Uint8Array([...salt, ...iv, ...new Uint8Array(encrypted)]);
  return btoa(String.fromCharCode(...packed));
}

export async function decryptMessage(packed: string, password: string): Promise<string> {
  const data = Uint8Array.from(atob(packed), (c) => c.charCodeAt(0));

  const salt = data.slice(0, 16);
  const iv = data.slice(16, 28);
  const ciphertext = data.slice(28);

  const key = await deriveKey(password, salt);
  const decrypted = await crypto.subtle.decrypt(
    { name: 'AES-GCM', iv },
    key,
    ciphertext
  );

  return new TextDecoder().decode(decrypted);
}