BREAKING BLOCK AND PRODUCT CIPHERS

The security of block and product ciphers is considered using a set theoretic estimation (STE) approach to decryption. Known-ciphertext attacks are studied using permutation (P) and substitution (S) keys. The blocks are formed from two (2) alphabetic characters (meta-characters) where the applications of P and S upon the ASCII byte representation of each of the two characters are allowed to cross byte boundaries. The application of STE forgoes the need to employ chosen-plaintext or known-plaintext attacks.

A pictorial illustration of conventional cryptography

In this paper we consider conventional cryptosystems. We illustrate the differences between substitution, transposition and product ciphers by showing encryptions of a highly redundant cleartext, a portrait. Also it is pictorially demonstrated that no conventional cryptosystem in its basic mode provides sufficient security for redundant cleartexts.