Something of mixed origin. In cryptography, typically a cipher system containing both public key and secret key component ciphers, where the public key system is used only to transport the key for the secret key cipher. It is the secret key cipher which actually enciphers and protects the data.
To give some foreground information: I acknowledge that I am a cryptography newb and not by any means an expert (and probably never will be). In a recent CS class we had several assignments writing ...