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Albert H. Carlson, Robert E. Hiromoto, Richard B. Wells


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.


Set theoretic estimation; block and product cipher; byte boundaries; known ciphertext attack; meta-characters.

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