2
$\begingroup$

Iterating multiple substitution ciphers is not mathematically different from using a single substitution cipher (3 Vigenere iterations with a 31-, a 32-, and a 33-letter key would essentially be a single Vigenere cipher with a 32,736-letter key), and a long enough message can be decrypted even with this long key the same way that a shorter message can be decrypted with a short key (likewise for iterating multiple columnar transpositions).

But if I wanted to use 3 Vigenere ciphers and 3 columnar transpositions on the same message, would doing all 3 substitutions first and all 3 transpositions second (or vice versa) be less secure than alternating something like "Vigenere-column-Vigenere-Vigenere-column-column"? Or would the same combined-substitution-transposition decryption techniques apply regardless of the order?

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.