Authenticated Secret Key Cryptography (AEAD) in TypeScript

AuthenticatedSecretKeyCryptography.ts

export default class AuthenticatedSecretKeyCryptography {
  public static readonly KEY_LENGTH_IN_BYTES = 16;
  public static readonly IV_LENGTH_IN_BYTES = 16;
  public static readonly TAG_LENGTH_IN_BYTES = 16;

  private static readonly ALGORITHM = 'AES-GCM';
  private readonly secretKey: CryptoKey;
  private readonly tagLengthInBytes: number;

  public constructor(secretKey: CryptoKey, tagLengthInBytes = AuthenticatedSecretKeyCryptography.TAG_LENGTH_IN_BYTES) {
    this.secretKey = secretKey;
    this.tagLengthInBytes = tagLengthInBytes;
  }

  public static async getCryptoKeyFromRawKey(rawKey: Uint8Array): Promise<CryptoKey> {
    // @ts-ignore
    return await crypto.subtle.importKey(
      'raw',
      rawKey,
      {
        name: this.ALGORITHM,
      },
      true,
      ['encrypt', 'decrypt'],
    );
  }

  public async encrypt(iv: Uint8Array, data: Uint8Array): Promise<ArrayBuffer> {
    return await crypto.subtle.encrypt({
        name: AuthenticatedSecretKeyCryptography.ALGORITHM,
        iv,
        tagLength: this.tagLengthInBytes * 8,
      },
      this.secretKey,
      data,
    );
  }

  public async decrypt(iv: Uint8Array, data: Uint8Array): Promise<ArrayBuffer> {
    return await crypto.subtle.decrypt({
        name: AuthenticatedSecretKeyCryptography.ALGORITHM,
        iv,
        tagLength: this.tagLengthInBytes * 8,
      },
      this.secretKey,
      data,
    );
  }
}