code: function Opdata(encryption, hmac) {
    this.encryption = encryption;
    this.hmac = hmac;
  
    if (this.encryption.length !== 32) {
      throw new Error("Encryption key must be 32 bytes.");
    }
  
    if (this.hmac.length !== 32) {
      throw new Error("HMAC Key must be 32 bytes");
    }
  }
docs: /*
  Opdata object. Construct a new instance with the keys and then use it to
  encrypt and decrypt data.
  - encryption {buffer} : The encryption key
  - hmac {buffer} : The hmac key