in cryptography, a product cipher combines two or more transformations in a manner intending that the resulting cipher is more secure than the individual components to make it resistant to cryptanalysis. the product cipher combines a sequence of simple transformations such as substitution (s-box), permutation (p-box), and modular arithmetic. the concept of product ciphers is due to claude shannon, who presented the idea in his foundational paper, "communication theory of secrecy systems".