key=

        # OpenSSL::Cipher.key=

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

---

Sets the cipher key. To generate a key, you should either use a secure
random byte string or, if the key is to be derived from a password, you
should rely on PBKDF2 functionality provided by OpenSSL::PKCS5. To
generate a secure random-based key, Cipher#random_key may be used.

Only call this method after calling Cipher#encrypt or Cipher#decrypt.