CodeBook•1.1 - App Store

This app contains 12 different methods for encrypting and decrypting secret messages. We will be adding more methods with future updates! Learn about cryptography with CodeBook.

Monoalphabetic Ciphers

A monoalphabetic cipher replaces one letter with another and uses the same substitution across the entire message. The popular Cryptogram puzzles that you see in newspapers and puzzle books are all monoalphabetic ciphers.

1) Caesar Cipher

2) Atbash Cipher

3) Keyword Cipher

4) Polybius Square 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 decryption much more difficult.

5) Playfair Cipher

6) Bifid Cipher

7) Trifid 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.

8) Rail Fence Cipher

9) Columnar Transposition Cipher

Codes

A code is a monoalphabetic cipher that is standardized. Because everyone knows the secret, these are not use for encrypting messages, but instead for encoding the message in a format that is more convenient for certain purposes.

10) Morse Code

11) Tap Code

12) ASCII Code

Note: This app is for educational and entertainment purposes. None of the encryption methods in this app are safe enough to use for actual secret messages.Requires iOS 5.0 or later. Compatible with iPhone, iPad, and iPod touch.