Stripe-CTF 3 Writeup • Hacker News Board

Re: Stripe-CTF 3 Writeup

#21

Post by brown9-2 » Thu, Jan 30, 2014, 8:18 PM UTC

jeremymcanally wrote: post #2

I got stuck on Level 3, partially because Scala is a little wacky (but I learned to appreciate it!) and partially because their specs were super terrible. They didn't mention it required substring matching or was case-sensitive until I'd been working on it for 2-3 days and then was out of time. Given the bad debug output (the head of a diff which often didn't show anything and didn't include what term the failure was…

To be fair though, there was an update to the level 3 README published on 1/25 which made some of the requirements (substring matching) a bit clearer.

Re: Stripe-CTF 3 Writeup

#22

Post by Geee » Thu, Jan 30, 2014, 8:19 PM UTC

I gave up on the last level, as I didn't have the time to commit. I'd say this CTF was too difficult/too much work for me. Last time with smaller challenges was more fun. The challenges were interesting in their respective subjects, but maybe they should have been a little bit more condensed in scope, particularly the last 2 levels. Although learning Scala and Go beforehand would have helped a bit.

Re: Stripe-CTF 3 Writeup

#23

Post by brown9-2 » Thu, Jan 30, 2014, 8:20 PM UTC

fragmede wrote: post #15

mkaufmann wrote: post #5

Great article, I am really eager to see the solutions in github. I guess there won't be many with c++ solutions. I only found the challenge two days before the end. My goal with the challenge was not to get the best solution, but rather use it as an exercise to practice the different languages and finding intuitive solutions. Level 0 as you wrote was really just a two line change. Level 1 was fun, because I tried to…

Mind posting your code for level3? I got that partitioning was the main trick but I am too unfamiliar with scala to reassemble the responses properly.

Here is how I merged the responses: https://gist.github.com/mattnworb/8717911

Re: Stripe-CTF 3 Writeup

#24

Post by icanhasfay » Thu, Jan 30, 2014, 8:21 PM UTC

philk10 wrote: post #8

icanhasfay wrote: post #3

Anyone else seeing links to empty repos?

"Note: I’ll add the source once submissions are off."

Didn't catch that, thank you.

Re: Stripe-CTF 3 Writeup

#25

Post by robbles » Thu, Jan 30, 2014, 8:25 PM UTC

ajdecon wrote: post #10

I got stuck on level3 over the weekend and then had to put it down due to life stuff. But it was still a ton of fun, and I learned a lot. If anyone from Stripe is here, do you plan to post the original problem statements and repos for the problems anywhere public now that it's done? I'd love to get a look at level 4... :)

Same situation here. I'd love to work through the problems at my own pace over the next few weeks though - I'd also like a way of replicating the solution testing that Stripe performs when you do an actual submission.

Is that infrastructure going to be released as well? Or would I need to just rely on the test harnesses and comparing my solution against the published ones?

Re: Stripe-CTF 3 Writeup

#26

Post by mathias » Thu, Jan 30, 2014, 8:27 PM UTC

Added a link to your write-up and solutions to the collection here: https://github.com/ctfs/write-ups/tree/master/stripe-ctf3

Re: Stripe-CTF 3 Writeup

#27

Post by gdb » Thu, Jan 30, 2014, 8:39 PM UTC

robbles wrote: post #25

ajdecon wrote: post #10

I got stuck on level3 over the weekend and then had to put it down due to life stuff. But it was still a ton of fun, and I learned a lot. If anyone from Stripe is here, do you plan to post the original problem statements and repos for the problems anywhere public now that it's done? I'd love to get a look at level 4... :)

Same situation here. I'd love to work through the problems at my own pace over the next few weeks though - I'd also like a way of replicating the solution testing that Stripe performs when you do an actual submission. Is that infrastructure going to be released as well? Or would I need to just rely on the test harnesses and comparing my solution against the published ones?

You'll be stuck with the test harness for the foreseeable future, unfortunately. Releasing the submission infrastructure in a usable form would unfortunately be a looot of work. We're working on open-sourcing a lot of the dependencies, though.

Re: Stripe-CTF 3 Writeup

#28

Post by ajtulloch » Thu, Jan 30, 2014, 8:50 PM UTC

Looks great! Nice scores.

I focused on getting the minimal passing solutions (e.g. Level 3, the distributed grep problem, only took ~5 LoC changes to pass, Level 4 was 162 LoC additions, 69 LoC deletions).

I wrote up my solutions at http://tullo.ch/articles/stripe-ctf-golfing/ if anyone was interested.

Re: Stripe-CTF 3 Writeup

#29

Post by jeremymcanally » Thu, Jan 30, 2014, 8:53 PM UTC

brown9-2 wrote: post #21

jeremymcanally wrote: post #2

I got stuck on Level 3, partially because Scala is a little wacky (but I learned to appreciate it!) and partially because their specs were super terrible. They didn't mention it required substring matching or was case-sensitive until I'd been working on it for 2-3 days and then was out of time. Given the bad debug output (the head of a diff which often didn't show anything and didn't include what term the failure was…

To be fair though, there was an update to the level 3 README published on 1/25 which made some of the requirements (substring matching) a bit clearer.

Yup, but that was kind of after I didn't have a lot of time to devote to it unfortunately. They did clarify but only after I whined. ;)

Re: Stripe-CTF 3 Writeup

#30

Post by zoz » Thu, Jan 30, 2014, 8:55 PM UTC

After many hours I failed to complete Level 4. How frustrating! But what a great experience. I think Stripe did a great job at building a programming challenge. By going through the challenge I learned something new in each of the following: Python, Ruby, Scala, Go, Node/Javascript, Git, Hashes, DDOS, Consensus Algorithms, raft, transactional logs, Inverted Indexes, BitCoin, IRC Chat, and more. Thanks Stripe you made me a better programmer.