Useful Code Terms



code   A code is a system of signals or symbols used for communication or a set of instructions for a computer.
cryptography   The science of secret codes.
cipher   Any system of hiding the meaning of a message by replacing the original message with a letter.
codebook   A list of replacement words or phrases in the original message.
Caesar-shift substitution cipher   A cipher that replaces each letter with three places shifted down the alphabet. There can be up to 25 shifts.
decipher   To turn a enciphered message back to an original message.
encrypt &nsbp; To encipher or encode.
ciphertext   the message or plaintext after encipherment.
private key   A key used by a receiver to decrypt messages from a public key system. The private key must remain secret.
public key   A key used by a sender to encrypt messages of a public system key, which is available to the public.
steganography   the science of hiding a message physically.

substiturion cipher   An encryption system in which each letter is replaced with another character, but retains the position within the message.

Vignere cipher   A polyalphavetic cipher that was made around 1500. It contains 26 seperate cipher alphabets that are Caesar-shifted and determines which cipher alphabet should be used to decode the message.
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