The task was to write, in Scala:

• an indexer that scans a bunch of input files, and
• a searcher that takes a query string and returns a list of lines containing it

It can be solved using the following:

In the indexer, tokenize each document, and create an inverted index …

If your service comes under a major DDOS attack, what would you do?

In the third level of Stripe’s CTF, participants were tasked to build a proxy to defend a couple of backend servers against a DDOS attack. The proxy needed to do the following:

• distribute requests across a …

This is the second installment of a series on Stripe's CTF 2014. You may wish to start from level 0.

Level 1

Level 1 proposed a crypto-currency named Gitcoin that used Git's SHA1 hashes. The player was provided with a git repository and asked to create a commit with a …

I participated in a week-long CTF hosted by Stripe in Jan 2014. This series of blog posts will cover some of the problems and their solutions.

Level 0

The first level was a breeze, and mainly served as an introduction/tutorial for participating in the CTF. We were given the …