Workbench

Guides

Each of these opens the workbench set up for one operation, with an explanation of what it is and when it is worth reaching for.

Analysis

• Inspect Paste something you did not write and find out what is actually in it.

Transform

• Bitwise operation Apply XOR, AND, OR, NOT or a shift to every byte against a repeating key.
• Case transform Change letter case, in one direction only.
• Hex dump Offset, hex bytes and printable characters, three columns side by side.
• Invisible characters Reveal or strip characters that take up no space on screen.
• Replace Find text and swap it for something else.
• Reverse Turn the input back to front.
• Unicode normalize Rewrite text into one of the four standard forms so identical-looking strings are stored identically.

Alphabets

• Morse code Dots and dashes, with the shortest codes handed to the commonest letters.
• PGP word list Turn a key fingerprint into words you can read aloud without being misheard.
• Spelling alphabet Alfa, Bravo, Charlie. For reading characters down a bad line.

Ciphers

• A1Z26 A is 1 and Z is 26, which is the whole of it.
• Affine cipher Multiply the letter's position by one key, add a second, keep the remainder.
• Alphabetical substitution Supply your own cipher alphabet and send every letter through it.
• Atbash Mirror the alphabet. A becomes Z, B becomes Y.
• Autokey cipher Start with a keyword, then keep going using the message itself.
• Bacon cipher Encode each letter as five A/B symbols, then hide the symbols where nobody looks.
• Beaufort cipher Vigenere with the subtraction the other way round, which makes it its own inverse.
• Caesar cipher Shift every letter a fixed distance along the alphabet.
• Enigma machine The German forces cipher machine, wired as it actually was.
• ROT13 Shift every letter thirteen places. Encoding and decoding are the same operation.
• Rail fence cipher Write the message in a zigzag across several rails, then read off one rail at a time.
• Vigenere cipher A Caesar shift that changes with every letter, driven by a keyword.

Polybius square ciphers

• ADFGVX A sixth symbol takes the grid to thirty-six cells, enough for the alphabet and the digits.
• ADFGX Split every letter into two of five symbols, then shuffle the whole stream with a keyword.
• Bifid Every ciphertext letter carries half of one plaintext letter and half of another.
• Nihilist cipher Polybius coordinates and a repeating keyword, added together as ordinary arithmetic.
• Polybius square Turn every letter into a pair of coordinates on a five by five grid.
• Tap code Taps for the row, a pause, taps for the column, knocked through a wall.
• Trifid Delastelle's cipher in three dimensions, with fragments of three letters inside every output character.

Encoding

• ASCII85 Four bytes packed into five printable characters.
• Base32 Bytes as 32 characters chosen to survive being spoken or mistyped.
• Base58 Base64 with the look-alike characters and the punctuation removed.
• Base64 Represent any bytes using 64 printable characters.
• Baudot (ITA2) Five bits per character, and a shift code that decides which alphabet you are reading.
• Binary Eight bits per byte, written out.
• Decimal bytes Each byte as a number from 0 to 255.
• HTML entities Turn markup into text a browser will draw rather than act on.
• Hexadecimal Two hex digits per byte. The default way to read raw data.
• Numeral base Rewrite a number in another base, anywhere from binary up to base 36.
• Punycode The form a domain name takes when it has to travel through systems that only speak ASCII.
• Quoted-printable The mail encoding that keeps text readable and writes everything else as =XX.
• URL encoding Percent-escape the characters a URL cannot carry as themselves.
• Unicode code points The exact identity of every character, including the ones pretending to be others.

Modern cryptography

• AES The block cipher behind most encrypted traffic, keyed by a passphrase or raw bytes.
• HMAC A keyed hash. Proves a message came from someone who holds the key.
• Hash Reduce any input to a short fixed-length fingerprint.
• RC4 The broken stream cipher that used to be everywhere. Kept for reading old traffic.