Project 6, 2015 Research Experience for Teachers Project 4, 2016
Substitution Cipher

Secret Key, Public Key, Hash Algorithms, Protocols, Authentication, Integrity, Confidentiality, Availability


    The text in the field labeled "encrypted:" is (or is close to being) a famous quote that is encrypted by permuting the letters A-Z, and characters space, comma and single quote. The JComboBoxes at the bottom of the applet represent a guess at the permutation that was used to encrypt. Make selections and click the "Decrypt" button. For example, if you think that the encrypted character A maps to the plaintext character D then open the list in the JComboBox labeled A and select D. Always click the "Decrypt" button after making selections to register the change. When the "Decrypt" button is clicked, the translation to plaintext is shown in the "decrypted:" field. However, if a JComboxBox setting is - (the default for all characters) then there will be no translation to plaintext for that character and blank spaces will occupy the plaintext positions corresponding to that character's position in the "encrypted:" field.

To get a new permutation while leaving the message the same click the "New Key" button. To get a new quote while not changing the permutation, click the "New Message" button. To get a new quote and a new permutation click both buttons.

Why this?

    It may seem that these types of ciphers are fairly secure since the number of possible permutations of the characters is roughly 2626 which is about 1036 so it is impractical for an attacker to be able to crack the permutation by doing a search over all possible permutations. However, as can be seen by using this applet and some human intelligence, these ciphers can be broken readily.

This applet allows a key change for the current message. There is nothing special about this - you just may see things better with a different key.