Monoalphabetic Ciphers
A monoalphabetic cipher uses the same substitution across the entire message. For example, if you know that the letter A is enciphered as the letter K, this will hold true for the entire message. These types of messages can be cracked by using frequency analysis, educated guesses or trial and error.
-Caesar Cipher
-Atbash Cipher
-Keyword Cipher
-Pigpen / Masonic Cipher
-Polybius Square
Polyalphabetic Ciphers
In a polyalphabetic cipher, the substitution may change throughout the message. In other words, the letter A may be encoded as the letter K for part of the message, but later on it might be encoded as the letter W.
-Vigenère Cipher
-Beaufort Cipher
-Autokey Cipher
-Running Key Cipher
Polygraphic Ciphers
Instead of substituting one letter for another letter, a polygraphic cipher performs substitutions with two or more groups of letters. This has the advantage of masking the frequency distribution of letters, which makes frequency analysis attacks much more difficult.
-Playfair Cipher
-Bifid Cipher
-Trifid Cipher
-Four-square cipher
Transposition Ciphers
Unlike substitution ciphers that replace letters with other letters, a transposition cipher keeps the letters the same, but rearranges their order according to a specific algorithm.
-Rail Fence
-Route Cipher
-Columnar Transposition
Other Ciphers and Codes
-Book Cipher
-Beale Cipher
-Morse Code
-Tap Code
-One-time Pad
-Scytale
-Semaphore
-ASCII
-Steganography
