Ctflearn Writeup Cryptography | Easy — Solutions

Jai Gupta
3 min readMar 12, 2020


CTFlearn (Capture The Flag) writeups for cryptography - Easy Catagory

Character Encoding

In the computing industry, standards are established to facilitate information interchanges among American coders. Unfortunately, I’ve made communication a little bit more difficult. Can you figure this one out? 41 42 43 54 46 7B 34 35 43 31 31 5F 31 35 5F 55 35 33 46 55 4C 7D.

This level is pretty simple; the flag is just converted into hex.

Flag- ABCTF{45C1115U53FUL}


Meet ROXy, a coder obsessed with being exclusively the worlds best hacker. She specializes in short cryptic hard to decipher secret codes. The below hex values for example, she did something with them to generate a secret code, can you figure out what? Your answer should start with 0x. 0xc4115 0x4cf8

ROX indicates XOR i.e perform XOR operation on these two strings to get the flag. Use this tool to perform XOR on the strings.

Flag- c0ded

Base 2 2 the 6

There are so many different ways of encoding and decoding information nowadays… One of them will work! Q1RGe0ZsYWdneVdhZ2d5UmFnZ3l9

As the challange name suggest it is converted into base64 encoding.

Flag- CTF{FlaggyWaggyRaggy}


There is a technique called bruteforce. Message: q{vpln’bH_varHuebcrqxetrHOXEj No key! Just brute .. brute .. brute … :D

This level again requires brute-forcing XOR. This online tool can easily do this with the key 17.

Reverse Polarity

I got a new hard drive just to hold my flag, but I’m afraid that it rotted. What do I do? The only thing I could get off of it was this:01000011010101000100011001111011010000100110100101110100010111110100011001101100011010010111000001110000011010010110111001111101

The level can be solved by just converting the Binary to Text.


Vigenere Cipher

The vignere cipher is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers based on the letters of a keyword.I’m not sure what this means, but it left lying around: blorpy gwox{RgqssihYspOntqpxs}

The given text is Vigenere Cipher and the key is blorpy. You can use this online tool.


Morse Code

..-. .-.. .- -. … .- — ..- . .-.. — — .-. … . .. … -.-. — — .-.. -… -.- — …. . .- .- -.- .. .-.. .. -.- . -.-. …. . . …

This representation is morse code. Use this online tool to decode.

HyperStream Test #2


The above text is encoded as Bacon Cipher which can be decoded by this online Tool:


Thanks for your patience, I hope you enjoyed reading. Happy Hacking...

Originally published at My CTFlearn writeup blog on March 12, 2020.



Jai Gupta

Build & Break | OSCP | Red Teaming | Penetration Testing