update

        # OpenSSL::Cipher.update

(from ruby core)
### Implementation from Cipher
---
    cipher.update(data [, buffer]) -> string or buffer

---

Encrypts data in a streaming fashion. Hand consecutive blocks of data to
the #update method in order to encrypt it. Returns the encrypted data
chunk. When done, the output of Cipher#final should be additionally
added to the result.

If *buffer* is given, the encryption/decryption result will be written
to it. *buffer* will be resized automatically.