Some identifying characteristics of base32 encoding are the padding characters (equal signs) and the upper-case and numeric alphabet. Is: JBSXSIJAKRUGS4ZANFZSAYLOEBSXQYLNOBWGKIDPMYQGEYLTMUZTEIDFNZRW6ZDJNZTS4= The base32 encoding of Hey! This is an example of base32 encoding. Some identifying characteristic of base16 encoding include the fact that it uses only hexadecimal characters and never needs padding (an equals sign at the end).īase 32 is very similar to base16 encoding but it has a larger alphabet, and uses padding characters (equals signs). This is a tool you can use to encode and decode base16/hexadecimal: The base16 encoding of Hey! This is an example of base16 encoding. However, it’s good to know they exist: īase 16 (hexadecimal) encoding uses the hexadecimal number system (0123456789ABCDEF) to encode text. I would recommend checking out the tables that describe the alphabets used for each type of encoding - knowing which alphabets correspond to which encoding schemes will help you identify the type of encoding at a glance!Īlso, this wikipedia page lists some of the more obscure binary to text encoding types that are beyond the scope of this post. Here’s IETF RFC 4648 if you want all the nitty gritty juicy details and also a long and usually dry read. The first “family” of encodings that I’ve seen frequently in CTF challenges are the base 16, 32, and 64 encoding schemes. Just like languages have specific alphabets, encodings have alphabets of their own. Different computer systems operate with different forms of encoding like different people use different languages. I like to think of encoding as a form of “translation”. Polyalphabetic Substitution: A Polyalphabetic substitution cipher uses multiple alphabets for substitutions, which makes the technique resistent to frequency analysis.Asymmetric Cipher: Two distinct yet related keys (public and private) are used to encrypt and decrypt the message.Symmetric Cipher: The same key is used to encrypt and decrypt the message.4 Essentially, the key is part of the input into a cryptographic function that modifies the function’s operations while creating ciphertext in such a way that you have to have the key to get the plaintext from a decryption function. Key: a piece of information that specifies the transformation of plaintext into ciphertext, and vice versa for decryption algorithms.Essentially, it assumes that the most frequent letter in ciphertext will correspond with the most frequent letter in the plaintext language, or that the most common three-letter word in the ciphertext corresponds to “the”. Frequency Analysis: A statistical method for cracking ciphers.Ciphertext: The encrypted message (usually looks like gobbledegook).Plaintext: The unencrypted or “original” message.Cipher: an algorithm for performing encryption or decryption.Encoding: to convert (something, such as a body of information) from one system of communication into another 1.I’ve found that Wikipedia has excellent articles on encoding and cryptographic systems, it’s a good place to look if you want more details on a specific encoding scheme or encryption algorithm. This random website that I found in highschool.Types of Ciphers - Symmetric (Single Key).The wonders of hex, decimal, octal and ASCII.It’s the resource I would have wanted when I was approaching my first CTF cryptography challenges! I provide examples of ciphertext (or encoded text) to help the build intuition that will help with cipher recognition! In my opinion, that’s the hardest part of solving CTF crypto challenges! Author’s note: The purpose of this post is to provide an introduction to cryptography, ciphers, and encoding techniques commonly used in capture the flag (CTF) challenges.
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