# Basic cipher info

## Basic Ciphers

Plaintext: the decoded, legible text of a message

Ciphertext: the encoded, illegible text of a message

Key: a variable value that is used to encode plaintext and to decode ciphertext

Caesar Cipher: a cipher that works by shifting letters through the alphabet

Brute-forcing: guessing many different passwords or key values

## Basic Computing

Base: a system of counting

Decimal (base 10): uses digits 0-9

Binary (base 2): uses digits 0 and 1

Octal (base 8): uses digits 0-7

Hexadecimal (base 16): uses digits 0-9 and A-F

ASCII: a standardized method of converting numbers to plaintext characters, and vice versa

Converting binary, octal, decimal, or hexadecimal into ASCII:

Convert the numbers into base 10

Turn the base 10 numbers into plaintext by checking them against an ASCII table

## Basic Webpages

If an ARG leads to a website, always check the page source!

HTML: a language used to create webpages

HTML tags: indicate how HTML should be read by your browser

Comments: text which is not displayed on a page, which can be used to conceal information

CSS: a language used to add style to HTML pages

Javascript: a programming language used in HTML pages

## Boolean Operators

Boolean Operations: Operations performed on binary numbers

NOT Operation: flips all the bits of a binary number

AND Operation: compares 2 binary numbers; if both bits are 1, then the result is 1, otherwise the result is 0

OR Operation: compares 2 binary numbers; if either is 1, then the result is 1, otherwise the result is 0

XOR Operation: compares 2 binary numbers; if each bit is different, the result is 1, and if the bits are the same, the result is 0

XOR Cipher: a cipher that uses XOR operation with a key value

## More Ciphers related to Vigenere

Vigenere Cipher: a cipher that uses a repeating keyword, and is comprised of many small Caesar ciphers

Vigenere Table: a table that can be used to quickly encode or decode a Vigenere cipher

Rolling-Key Cipher: a cipher identical to a Vigenere cipher, except the key is long enough that it does not need to repeat

Autokey Cipher a Vigenere/rolling-key cipher that incorporates the plaintext into its key