Let's say that you need to send your friend a message, but you don't want another person to know what it is. You can use a full-blown encryption tool, such as PGP. If the message isn't that important or if it is intended to be decrypted by hand, you should use a simpler tool. This is a page dedicated to simple text manipulation tools, which all can be replicated with just paper and pencil.
If you know of another cipher that you think should be on here or a tool that would be useful, request it and perhaps it can be added to the site.
- Affine - Similar to a Caesarian shift, but also adds in a multiplier to further scramble letters.
- Atbash - A very simplistic cipher where you change A to Z, B to Y, and so on.
- Baconian - Used to hide a message within another message by using different typefaces or other distinguishing characteristics.
- Base64 - This is typically used to make binary data safe to transport as strictly text.
- Bifid - Breaks information for each letter up and spreads it out in the encoded message. An easy and fairly secure pencil & paper cipher.
- Caesar - A Caesar cipher lets you add an arbitrary value, shifting each letter forwards or backwards. Traditionally, the offset is 3, making A into D, B into E, etc.
- Columnar Transposition - Write a message as a long column and then swap around the columns. Read the message going down the columns. A simple cypher, but one that is featured on the Kryptos sculpture at the CIA headquarters.
- Double Columnar Transposition - Because two is better than one. This was used by the U.S. Army during World War II.
- Gronsfeld - This operates very similar to a Vigenère cipher, but uses numbers instead of a key word.
- Letter Numbers - Replace each letter with the number of its position in the alphabet. A simple replacment method that is usually the first one taught to children and is still an effective way to obscure your message.
- Morse Code - Once used to transmit messages around the world, this system can still be used in certain situations to send messages effectively when alternate mediums are not available.
- One Time Pad - A virtually uncrackable cipher that relies heavily upon a random source for an encryption key.
- Playfair - This cipher uses pairs of letters and a 5x5 grid to encode a message. It is fairly strong for a pencil and paper style code.
- Rail Fence - A mildly complicated one where you align letters on different rows and then squish the letters together in order to create your ciphertext.
- ROT13 - A popular method of hiding text so that only people who actually take the time to decode it can actually read it. You swap letters; A becomes N, and N becomes A. It was quite popular on bulletin board systems and Usenet newsgroups. You can do it with the cryptogram solver also, if you make A=N, B=O, C=P, etc.
- Rotate - This acts as though you are writing the letters in a rectangular grid and then rotating the grid to the left or right 90°
- Skip - To decode this, you count N characters, write down the letter, count forward N characters, write down the letter, etc. It is used for section 3 of the Kryptos.
- Substitution - Substitute your plaintext letters with other letters, images, or codes. Includes two common pigpen ciphers and the Sherlock Holmes' Dancing Men cipher.
- Übchi - A double columnar transposition cipher that uses the same key, but adds a number of pad characters. Used by the Germans in World War I.
- Vigenère - Based somewhat on the Caesarian shift cipher, this changes the shift amount with each letter in the message and those shifts are based on a passphrase. A pretty strong cipher for beginners. Functionally similar to "Variant Beaufort" and this also supports autokey.
- Analyze - Shows how often certain letters appear in your text. Used primarily to assist in decryption.
- Cryptogram Solver - If you have a plain text message, this will help find possible solutions in a matter of seconds. It works with simple substitution ciphers in plain English only.
- Cryptogram - This helps you manually solve simple ciphers, which are methods where you replace one letter with another.