 How's it going everybody? My name is John Hammond and welcome back to the Repico CTF 2019 video. This one is called La Cypher D and it's worth 200 points in the cryptography category. That title is a reference to La Cypher D Indecipherable, or the Cypher, the Indecipherable Cypher, which is a homage to the Vignier Cypher, Vigenier. I'm always bad at pronouncing this. Everyone yells at me. It's cool. You can do it too. It says, I found the Cypher in an old book. Can you figure out what it says? Connect with this netcat command. So let's hop on over to our terminal and let's run that. I will make a little, I guess, La Cypher D. However, that's actually yeah, Cypher D. Okay, cool, whatever. I will make a simple connect script for that just to encapsulate it nice and easily for us. We don't really have to actually do anything with that netcat connection. It's just to give us the data, which is interesting and peculiar, but it gives us seemingly nonsense, which is the Cypher text or this encrypted message. But based off the title of this challenge and kind of with an inkling, this should be able to just be the Vignier Cypher, Vigenier Cypher. You can see what our flag should be denoted here, but we need to go ahead and decrypt this. If you haven't seen CTF Katana, I would totally recommend just go checking out that resource. That might be handy for you. That is just the document rendition of the Katana mentality. We have the automated tool that we're slowly rolling out and doing some cool things with, but working with the Vignier Cypher, you need to kind of know the key before we can start to brute force it. CTF Katana will showcase a lot of different tools and techniques and avenues and routes. You can go down though with different kinds of capture the flag challenges and cybersecurity and tech things. That's on my github, github.com slash John Hammond CTF hyphen Katana. That's a document, just a resource and maybe some ideas. There is a note here for Vignier Cypher though. One of the references that you could go to is this mygeocachingprofile.com. They have a pretty nice site that I've seen is pretty trustworthy and reliable for quickly being able to brute force this thing. It takes a little bit of time to actually just, hey, I don't know anything about it. Maybe it's Vignier Cypher. Let's just toss it in there. No trying to determine the key and message based off of that site's own analysis of the encrypted text. Takes a little bit of time. If you want to jump around, you could try those other resources that are noted there. I think there's a Vignier Solver and my personal Python code that I've written in other CTFs, but we should eventually get a result here and it tries to figure out what this message should be. I'm assuming this is supposed to say it is interesting how, etc, etc. But the key that it found looks to be what could have been the word flag and repeated over and over again, but it just didn't get it right. So we could do our own deductive reasoning and try to shift using this key flag, which would make sense, right, given the challenge here. And that will actually decrypt to what we're really looking for. It's interesting how in history people often receive credit for things they did blah, blah, blah. There is our flag Pico CTF. Here we go. And let's note our flag dot text here. Let's run finish. So we can make that executable. I'm sorry. Wow, we can mark that as complete. And we'll paste that in. And I missed it. Bello or Vignier cipher text. Oh, it needs to be capital there. There we go. Because it was lowercase how that's a directory nano. It was less cipher flag. The way that that geocaching profile dealt with it is converting it all to lowercase. But that is what we needed. We need to include our capital CTF in that case. So thank you guys for watching. Super simple. Go check out CTF Katana if you haven't seen it before. So maybe some good resources in there or just some ideas. And please feel free always add stuff to this. Maybe it's a good repository that some people have found some use with ad pull requests, ad issues, ad stuff that I have a spelling issue for. But this has about 484 stars. So I think it's become a good resource and some people seem to like it. Definitely check that out if you haven't heard of it. CTF Katana on John Hammond GitHub. All right. That's the end of the video. Bye.