Month: April 2017

Sunshine CTF – Vanity – Crypto

You need to buy some things, and luckily the local merchant accepts Bitcoin! You found out he only checks that the first four characters of his address and the one you send the coins to. Can you make him think you are sending him the coins while they really go to yourself?

For this challenge, we are given a server to connect to which gives the “merchants” Bitcoin address and asks for our Bitcoin private key in hex. The goal of the challenge being to generate valid addresses that begin with the same four characters. This is fairly simple as the first character is always a “1” so we only need to find the first three characters. After a bit of research, a program called VanityGen was found. This program takes a string and generated Bitcoin addresses and their corresponding private keys! Getting the flag from this point is trivial, a few commands later and we get it!



Posted by Tanner in CTF, Posts