Product cipher definition
A product cipher is a cryptographic method combining two or more transformations to encrypt the data. It’s designed to deliver a higher level of security compared to ciphers that use only one transformation technique. Transformations can be substitutional (like changing characters or bits) and permutational (like rearranging the order).
How product ciphers work
To turn data from plaintext into ciphertext, product ciphers carry out multiple rounds of substitutions and permutations, each round using a different subkey derived from the main key. It results in securely encrypted data that’s very difficult to unencrypt without the proper key.
History of product ciphers
Product ciphers can be traced all the way back to early 20th-century encryption devices — like the Enigma machine used by Germany during World War II. The modern concept of product ciphers was formalized by mathematician Claude Shannon in the 1940s, who recognized the value of combining different cryptographic operations.
Product cipher examples
- DES (Data Encryption Standard) is a classic example of a product cipher. It uses 16 rounds of substitution and permutation to encrypt 64-bit blocks of data.
- AES (Advanced Encryption Standard), which replaced DES, uses a more complex series of transformations for increased security.