Its simplicity and its cryptographic strength compared to simple substitution and Vigènere (a polyalphabetic substitution cipher) made it an immediate success as a field cipher, used by the ...

What Sanchez worked out was a simple monoalphabetic substitution cipher. Each picture shown was a combination of three things: one of eight images (including a butterfly, a seahorse, an apple, and ...

You can make a message secret in countless different ways. One common way is to use a substitution cipher, in which one letter is substituted for another. Another is to employ a transposition ...