auth_data=

        # OpenSSL::Cipher.auth_data=

(from ruby core)
### Implementation from Cipher
---
    cipher.auth_data = string -> string

---

Sets the cipher's additional authenticated data. This field must be set
when using AEAD cipher modes such as GCM or CCM. If no associated data
shall be used, this method must **still** be called with a value of "".
The contents of this field should be non-sensitive data which will be
added to the ciphertext to generate the authentication tag which
validates the contents of the ciphertext.

The AAD must be set prior to encryption or decryption. In encryption
mode, it must be set after calling Cipher#encrypt and setting
Cipher#key= and Cipher#iv=. When decrypting, the authenticated data must
be set after key, iv and especially **after** the authentication tag has
been set. I.e. set it only after calling Cipher#decrypt, Cipher#key=,
Cipher#iv= and Cipher#auth_tag= first.