Minetest Circuit Challenge - Google CTF 2019 Qualifier

Solving the Minetest Hardware Challenge from the Google CTF 2019 Qualifier.
* Google CTF: capturetheflag.withgoogle.com
* Solution Script: gist.github.com/LiveOverflow/...
* blog: liveoverflow.com/minetest/
=[ ❤️ Support ]=
→ per Video: / liveoverflow
→ per Month: / @liveoverflow
=[ 🐕 Social ]=
→ Twitter: / liveoverflow
→ Website: liveoverflow.com/
→ Subreddit: / liveoverflow
→ Facebook: / liveoverflow
=[ 📄 P.S. ]=
All links with "*" are affiliate links.
LiveOverflow / Security Flag GmbH is part of the Amazon Affiliate Partner Programm.

[@LiveOverflow]

If you liked this video, maybe checkout this related video: kzbin.info/www/bejne/hoKzgGiQadGJirc

[@ubuilditmtserver7393]

The video is great! You should make more content on Minetest, I make content for Minetest and Its fun to make tutorials especially, because every view is someone you helped. I am a small KZbinr, but im not in it for money, I want to show how excellent Minetest is.

[@claracrazy]

warte warte warte.... du bist deutscher?

[@tim-4368]

@@ubuilditmtserver7393 and excellent it is

[@ubuilditmtserver7393]

@@claracrazy Ich bin 12,5% Deutscher, ich spreche etwas Deutsch, aber nicht viel.

[@jlbminestine698]

is there a render download where i can zoom into the individual logic gates?

[@karenwest6350]

God, Minetest. I remember using it when it first released. I'm honestly super happy to see it still being developed.

[@aleksandersats9577]

i remember playing minetest on ubuntu because minecraft wasn't supported there back then

[@BamBamKam12]

@@aleksandersats9577 Yeah, I remember when I was I think 11, didn't have the game at the time, shit was epic

[@tim-4368]

Its improvee alot, tons of mods amazing servers. Come back and try it out :D

[@batlin]

I remember trying it maybe 5 or 6 years ago... amazed to see how far it's come.

[@ianmoore5502]

Anyone remember gameboom

[@bogi1]

Can we have minecraft? Mom: We already have minecraft at home. Minecraft at home:

[@braddles]

Free, and highly customizable!

[@tim-4368]

Great game, check it out. Tons of unique servers

[@sommie4935]

Minecraft at home: open source and built with C++

[@Jordan4Ibanez]

The default game is committee driven ☹️

[@mateus1491]

At least they didn't fucked up the battle mechanics like mojang did with combat update

[@caeborges6831]

12:07 “Pretty straightforward challenge”. LOL

[@Euroliite]

What he meant by that is the he knew what the goal was (to solve the circuit), he just had to figure out how to implement it. Where as with some other challenges you spend a lot of time researching and tinkering to figure what you even need to do (where is the vulnerability, how can it be exploited, etc.)

[@oktal8589]

surprisingly unsurprisingly simple. hooray!

[@Sednas]

@@oktal8589 Ceave

[@displayname2149]

Bottom line is, LiveOverflow is an intellectual animal. In fact, anyone who can understand this is on another level to me.

[@alski]

parsing in general isnt usually that crazy

[@austindrane3162]

I was really close to finishing it by hand I only had 1 or 2 levers that were wrong. Really made me mad then I read a writeup and was upset with myself but I learned more

[@CowBeatsCrow]

How long did it take to do all that by hand?

[@vedadhadzic8004]

Hey @LiveOverflow. I solved this with one of my mates. We were actually the second ones to solve it. We looked at the code documentation and then went and built the parser. The parsing was by far the most annoying part. The next annoying part was the orientations of the mesecon parts, because of course its different for each component... ugh. Then we simply ran a DFS-like algorithm to find the connections. Put everything into Z3 and viola, the correct input pops out. It was a really cool challenge. We never made any visualisations of it like you did, that might have been useful.

[@Mert-is5nm]

I genuinely don't understand anything but love to watch your videos

[@johnnynakazono6626]

I was think that i' m the one that don't understand anything hahaha

[@mcruff3]

@@johnnynakazono6626 I'm confused from your statement.

[@johnnynakazono6626]

@@mcruff3 I 'm a confused people, sorry

[@zafarshahid4834]

Same

[@Timotheeee1]

this video was much easier to understand than his typical stuff. he converted the map into a format that z3 can solve.

[@__mk_km__]

This was my recent hobby: reversing file formats and creating parsers for them. For some reason I quite enjoy doing it

[@billigerfusel]

Weird fetish but ok

[@deltanedas]

god bless you

[@dummypg6129]

Ok fetish weir flex

[@mamupelu565]

how do you do it?

[@ahmedmani1051]

@@w花b fetish ok flex weird

[@mattt2684]

You 100% deserve a like for all these types of videos. I can't believe the amount of effort you put into your channel and these write-ups. You deserve at least 5x the amount of subs you have

[@0xC272]

it's 3am, just got the notification worth it for LiveOverflow

[@chrissxMedia]

1pm

[@rhysesipad7037]

3am for me too lmao

[@ChumperDumper]

Found this in my recommended. Loved your use of recursion to solve this problem. As you probably know, a lot of people will just use loops instead of a recursive function, but they miss out on the beauty of the code. Great video!

[@mathlover7427]

I hear Minecraft, I press like. This might be very good content for the KZbin algorithm to recommend to nine year olds, especially due to the rise of Minecraft videos. Might even convert your channel into a Minecraft channel (in the security aspect, of course)

[@figboot]

Minecraft? When did he play or show minecraft?

[@mathlover7427]

@@figboot I didn't say he played Minecraft, I reacted to the part where he said open-source Minecraft clone :)

[@zCri]

@@gwentarinokripperinolkjdsf683 mc bedrock bad java edition good

[@ChrisD__]

Why Minecraft? The video is about Minetest, they're very different projects with different goals, just an undeniably similar aesthetic on the surface.

[@mamupelu565]

just look at minecraft source code and look for possible exploits

[@cntrix2047]

this goes way over my head and I wasn't really able to follow it after a few minutes, but it was still enjoyable to watch until the end. great job

[@Steven-vh6fg]

lol same knew bits and pieces of programming though.

[@cptpinecone]

Friggin bananas what you can do with a program. The amount of complexity is so cool!

[@Jordan4Ibanez]

I think you're the only KZbinr that understands that minetest is the engine and you build games into it, I will have to do a video on installing mods

[@Xerathiel]

Naruto usee clone jutsu at every branching path. The clone with the correct path commits sepouku and gives the information to everyone else. They disperse and naruto knows the correct path.

[@forestjohnson2664]

oh THHHAAAATS how quantum computers work

[@Ramzan308]

Genius

[@funposting8912]

Also known as “Well that sure made things run faster, but look, someone exploited it, patch the microcode and slow everyone’s processors down by 30%”

[@GeorgeTsiros]

so basically massively parallel execution

[@JustSomeAussie1]

so fucking cringe

[@vega1287]

good thing they never use latches or flip flops for tis witch would make it so mich worse

[@stepanbazrov6330]

Mesecons_extended has latcher and flip-flop :D

[@tylerchiu7065]

Sci craft: hold my normal minecraft logic circuit

[@powdermcdust8335]

Build another circuit in minetest that brute force attacks the levers haha just a simple incrementor no? Though it might take 500 years depending on the speed of the logic gates...

[@zungaloca]

minetest is c++ not java garbage

[@__jan]

@@zungaloca java isn't garbage, minecraft is made of garbage code

[@KruK666PL]

​@@__jan Java is garbage when come to making games. Minecraft is huge game. No matter how you will write this in Java, it will be slow. Because in Java you cant control memory.

[@oblivion_2852]

Also depend on if minetest has a command to tick warp (run the simulation without a delay/update limit)

[@tomcho8221]

@@zungaloca yes but mods are written in Lua and stuff like mesecons is pretty slow. It doesn't deal well with having a lot of blocks loaded at once either.

[@lwlx]

nachdem ich das video geshen habe habe ich 11 stunden an CTF challanges gearbeitet. es war hart aber geil danke!

[@3au4ik]

Challange is to connect right inputs with output according to visual data given. Well done, I liked very much your solutions, thought I think there could be optimizations in the code to speed up the process. If someone didnt understand the task: You are given numerious questions and the only one right answer. Questions are based on primitive AND\OR\XOR (etc) logic given by custom data-from. The challenge is to get the (true\false -> 1\0) string of the right way to go to the end.

[@GeorgeTsiros]

i like these kinds of challenges which require knowledge from different areas and how to combine it/them

[@MichaelOfRohan]

8:48 this is why this guys is good at intuition. You see that improvisation? Gold.

[@hassankahdim4220]

it amazes me that you have the talent and the passion to still solve challenges that are so consuming like this. Dude you are just straight off the charts and deserve an award

[@noahb8991]

This was so interesting to watch! Hope to see some more CTF vids!

[@tusharmaurya1668]

"I thought that sounds like FUN", F**k yeah it does!

[@TheZipippino]

Wow man, that’s amazing! I think i will try some basic CTF, i really like the way you solve em

[@QuentiumYT]

Omg! For me the most interesting CTF I've watched, it was so nice to see that! Thanks for the awesome video

[@MaximumJoy]

The level of logic here is amazing. I get confused which response to use when for example somebody says "do you not want it"...

[@djh1455]

never heard of z3 but mindblowing seeing such a large circuit with inputs being "solved" so quickly. great example of quantum computer algorithms usecase, "do all paths at once and go with the one with this result" concept.

[@RamkrishanYT]

Imagine Seth Bling designing such a game.

[@Hentai7890The2nd]

it has been awhile since I've seen your videos. I didn't realize who you was until I saw the intro and I was like "holy crap its this guy! I wonder how he's been?"

[@tiagolucascastro9178]

I understand absolutely nothing about programming, and still watched the video and found it really interesting! I only wish I had more time to learn it.

[@753238]

you don't nned to learn it an AI will probably beat the best man

[@satibel]

have you made an hello world yet? 9 month is enough to make a baby, you probably found some time to make a program ^^

[@supernpstr]

Quite impressive. As you mentioned, pretty much a programming/data mining challenge. Would you expect such challenges because it's Google?

[@brodiemcinnes1550]

I don’t have a clue what he’s talking about but it’s entertaining to watch his problem solving, nice :D

[@tayfun6378]

8:49 I love these details

[@kangalio]

Yeah that was kinda funny

[@ozgurhanc8153]

Tayfun Ben hiçbir şey anlamadım Bana anlatır mısın

[@tayfun6378]

@@ozgurhanc8153 it goes to the left derken kendi solunu gösterdiği için ekranda sağı gösteriyor onu düzeltmiş :)

[@ozgurhanc8153]

Peki videonun genelinde anlattığı şey detaylı açıklaman mümkün mü

[@zacksargent]

Wow! This was really interesting! I feel like I also learned a fair bit as well. Thank you for the wonderful video.

[@Johna41223]

Ah, finally a liveoverflow video that I can somewhat actually understand deeply

[@ubuilditmtserver7393]

I play Minetest and own a server, The game is excellent to mess around with, have fun!

[@puffonxe_9529]

Me: Teacher, can we play Minecraft today? Teacher: Hmm.... Yeah sure.. *The minecraft we played*

[@theoriginyt4869]

From all the people living on the earth, why your teacher?

[@puffonxe_9529]

@@theoriginyt4869 because coding ??? 🤔🤔🤔

[@the32bitguy]

Minetest mod developer here, minetest is great for programming, I have spent a while doing it with multiple different projects. The primary feature it that it uses Lua which is superior in ease of use and single threaded performance to Python.

[@mastermax7777]

wow so much work. thats why i dont really like to do challenges.. its really time consuming especially if you dont know what your doing

[@vega1287]

a tool i know of that will simplyfy the boolian equation is multisim althoagh it is really designed for cirquit simulation , subscription based and i am not shure if it will acceot such long formulas if you have the entire equation i might give it a try

[@Valery0p5]

And that's how "Redstone engineers" used electronic engineers tools to create big and complicated circuits in Minecraft

[@Valery0p5]

@RedIAnima YT I was talking about the circuits

[@itzhakramm44]

you videos are always a pleasure to watch, and really interesting, good job.

[@elikelik3574]

You guys keeping me surprise with your knowledge. Well done. if honestly for me it is still difficult to understand every step but hope one day will know such things properly.

[@SaifAli-tz7zz]

The solution for this challenge was that hard and time consuming. I am literally wondering what about those people who made this challenge. Really amazing people out there. Love from Pakistan 💝

[@Mattluna17s]

Currently 5am and this was on my recommended. Have no idea what is happening but it was interesting😂

[@gutembergandrade1093]

"straightfoward challenge" loved it

[@ricardotech]

Appreciate your mindset strategy to solve this ctf

[@89elmonster]

Wow, I dont even know what to say this is amazing. Making a program so you can view the map is impressive. I have no words to describe how cool that is.

[@Bravo-oo9vd]

The teammates' reaction was what made the video for me

[@TurtleFul]

Aww I was looking forward to seeing Z3 solving it with a graphical window showing how it traces the circuit. Well Awesome job anyway _D Also I would be interested in knowing if you could do a similar thing with minecraft redstone circuits ?

[@iProgramInCpp]

You can't have wires longer than 15 blocks that don't lose signal unless you use repeaters.

[@elmegagamer1]

Minecraft doesnt have 1-block logic gates , so it would be hell to parse , also because there's like 10 different designs for every logic gate , and redstone is pretty quirky sometimes , i'd say no unless it is a circuit specifically built for that purpose, or you have A LOT of time in your hands

[@iProgramInCpp]

@@elmegagamer1 not even Minetest does unless you have that mode

[@iProgramInCpp]

@@elmegagamer1 not even Minetest does unless you have that mod

[@hikaru-live]

I believe this is generated from some HDL source. If the parser can detect the nets, you can revert the circuit into Verilog and throw a logic simplifying algorithm on it.

[@chigozie123]

Nice to see a programming challenge. In codeforces, this challenge will be part of 3 other challenges you will need to solve in 2 hours.

[@mika2666]

We had Z3 in school when learning reasoning and logic, pretty handy

[@arekcegowski8066]

me: being super interested thorughout the first half of the video "and now we come to the actual interesting part" ooooh

[@olfmombach260]

I like how the red dot from 9:30 and on is from the intro

[@AlanMedina314]

Another extremely interesting video, thank you for sharing. This challenge is truly interesting.

[@ronoverflow5890]

Well this is a weird Minecraft lets play. Jk, loved this episode really :)

[@mafiozos2000]

This could be harder easily. The could ask for a simplified version of the circuit. In this case you should trace it as a maze with tri-state cables, multiple times from start to end (each time output of a node -gate- is z, it starts tracing the next input untill all circuitry is explored, and all this, for each different set of inputs), to get a karnaugh map, then simplify it and generate a simplified version of it. This challenge was brilliant tho

[@rosco3]

I undestood what needed to be done from the start but had no idea how to do it nor where to start looking.

[@ianaviso1287]

When he say fuckkkk that literally killed me😂

[@jlbminestine698]

is there a render download where i can zoom into the individual logic gates?

[@lowzhao]

z3 seems very cool! Nice explaination!

[@prob_here]

we cant find another live overflow in this entire youtube community

[@justtest]

I wonder if author of this puzzle expected challengers to use Minetest Lua mod to solve it. Well, i doubt there is available Lua solver, so parsing is right approach in this case. I am glad to see that content created by our Minetest community was useful for people.

[@tomcho8221]

I imagine it's a lot faster, don't need to have all the unneeded blocks loaded in memory or for the game to run calculations not strictly related to solving it.

[@anghbalahr2971]

Never let someone from Bethesdas echelon watch one of these videos, or their heads might experience the life-feature of spontaneous implosion.

[@altaircarter9352]

Man i need to try that game out, looks fun.

[@modx5534]

I did not even know there is an OSS minecraft clone :). Z3 looks were interesting tho, guess I should give it a try with some (albeit much easier) circuits^^

[@aapollo100]

JW do you have your oscp? Do jobs in EU want to see a lot of certs like here in the US? Im a jr CS student thinking i need to get some certs before i graduate.

[@KeithMakank3]

What did you compile JavaScriptCore on? I keep trying to compile it on my Ubuntu machine but cmake just hangs for days :(

[@unodos1821]

Nice wire steippers, I love them👍

[@black_platypus]

So, what was the input? Does it result in any interesting number or ASCII?

[@levrairobe2133]

Do you know you are the look-alike of Gonzague, a French youtuber. Its breath-taking

[@TheHTMLCode]

Absolutely loved this task

[@sypeiterra7613]

I would love to see the mapping program be used on the round world mod for minetest

[@retpolanne]

Nice video, really inspiring for people who want to find bugs. I wonder if you can kubectl to this cluster. 13:33 hey, if you get access to the host, you can use strace to trace the container processes pid.

[@szulerinio]

It's almost 2am and I should be asleep, but instead I watched this vid with my mouth open and I feel stupid Why am I even trying to do something with programming :V I am soo far behind all other people

[@MikeDBZ]

pretty much this. I thought i was chugging along well in my programming classes btu wtf is all this. I'm watching defcon videos and now a bunch fo this guys videos and I'm crying. I went into an Info Sec degree btu this guy is on another level. You just have to know much. I can think of the many other jobs i could have done where u need to know far less, and it would have paid just as much or more. Like wtf is this. these videos are just crippling. Even the msot basic warm up challenges on picoCTf, I'm like what. They open shit on a console and connect to servers somhow or shit through console? like what? wtf is goign on. what am i even doing.

[@berylliosis5250]

Hey, don't be down on yourself. Everyone starts somewhere. Programming is just something to master like everything else. When I first started programming, I didn't understand most of these concepts but now (~6 years later including the yearlong break I took) they're intuitive and natural to me.

[@The4lexO]

Verilog is not a programming language, it's a description language

[@malekgtx3549]

Yo have to add minecraft to the title and boom visits. Pretty good video i enjoyed so much

[@fosatech]

9:22 All those elif's make me anxious 😂 I know python has switch statements, but idk if you can use boolean operators with them. Something I should look into. Also, are you coming to DefCon this year?

[@karlkastor]

Python doesn't have switch statements...

[@fosatech]

@@karlkastor try { "a": do_a, "b": do_b, "c": do_c }[input](var_to_pass)

[@LiveOverflow]

Wow that’s an ugly hack :D If you look closely it’s not actually a switch-case. It makes a inline dictionary with function values. And the index will just get the right entry. And call it.

[@fosatech]

@@LiveOverflow I guess you're right 😂 It is the closest python has to switch statements though, and I've seen it used alot. I personally prefer it to rows of elif.

[@conrrr]

he does all this work, i google and find answer, thanks man

[@iVideo1011]

What monospaced font do you use for programming?

[@guy6826]

I have no idea what the hell you’re talking about, thank you for the video

[@hikaru-live]

Well for me my solution would be map out the circuit, somehow convert it into a netlist or HDL source for some FPGA software, then run a logic optimizer on it.

[@Conorokelly3]

Hey, Would love to know how long the whole process took start to finish! Just as a ballpark! Thanks!

[@LiveOverflow]

I didn't track time exactly, but probably around 12-16h

[@Conorokelly3]

@@LiveOverflow Thanks for the reply! Exactly what I was looking for.

[@siyabuilt]

Tolles Video mach weiter so!

[@purplpasta]

Me: Hears that the reaction is german Also me: Happy german noises

[@_ev0n]

owo

[@fisherjam5182]

In German: UwU

[@sebastienleroy2706]

Hi everyone, do you know if there is a mod that allows you to have distributors ( like on minecraft ) but on minetest 5.4 Thanks

[@satosiwu148]

I wonder can you generate a huge prolog program from the map and let the prolog console solve it? 🌝

[@CZghost]

Dude, when I saw that HUGE circuit, I was like "Holy f*ing sh*t". Exactly the reaction of the guy :D :D

[@DemonArcMonster]

Where do I go to learn more about how to do this kind of work? I have zero CS experience and don’t know where to start!

[@jakubtrzebiatowski5308]

Great, thanks for the upload

[@madDragon08]

How much more difficult would this have been if some of those gates had timing functions connected to them that changed the state of other logic gates, or even the whole board for that matter? I was thinking about this being a surface circuit, where a person could copy the surface and struggle to get a solution, but they were missing a whole additional layer below the surface, but as you said, the WHOLE map is copied which would reveal the full scale. I suppose those timing gates would simply be treated as more paths to trace back, so maybe it wouldn't be worth it.

[@kariboo84]

this video will reach the sun

[@dcpngn3740]

And now I'm modding in Minetest

[@Juanixtec]

man, I understand what you say but at the same time I'm so intimidated by it, it's insane...

[@wouterfaes2309]

i have no clue what he was talking about , but it had some kind of minecraft and it seemed interesting so i watched it all

[@BlackHermit]

Secrets of the mountain climber!

[@merthyr1831]

Minetest is awesome :) Far more moddability than Minecraft proper -- almost a totally feature-complete game engine with a minecraft clone as an example project :D