How to Decode a QR Code by Hand

[@GabrielTobing]

When you're that one guy that is watching this for fun, and not for any work related reasons.

[@technologyclub6870]

Who dafaq needs this for work 😂

[@Simon-vf2bq]

im doing this for writing F*ck you

[@BigJoe2286]

I have run out of things to do during quarantine lmao

[@ndanilo]

@@technologyclub6870 I'm using it to solve a CTF challenge.. we have to decode a QR code that has solid color polygons on top CTF in Computer Security (en.wikipedia.org/w/index.php?title=Capture_the_flag)

[@technologyclub6870]

@@ndanilo wow that seems interesting

[@RonNV11]

I don't ever comment on videos. But I have to thank you for this. This was awesome. I can imagine the time it took to create all of these graphics, and want to thank you for your efforts. This is exactly the kind of thing I love to find online.

[@masterblaster7782]

Upvote :D

[@leskerwint2607]

Why?

[@panchi2090]

@@leskerwint2607 because maybe there are people who find this useful and the guy who made the video used it's time for helping that people and making it easy to understand.

[@rudellsanders8594]

a

[@AgentM124]

Someone make a vacation QR puzzle book. Would be terribly hard but fun. (For the real nerds)

[@pfhrmb]

What? A puzzle book where you debug by hand and see what the code is?

[@AgentM124]

yeah the solution of the code of course is _You are aboslutely no-life_

[@pfhrmb]

Mistory Minecraft It's funny you say that because you play minecraft.

[@AgentM124]

Oh, but it is not no-life. Responding to this comment actually is...

[@robottwrecks5236]

Mistory Minecraft I would totally do that. Also I have no life.

[@MM-ts9jy]

Dude I've been looking everywhere on youtube a video explaining how QR codes work, and they all say "How a QR code WORKS" but all they do is explain what they are and how to download an app to install it (aka bullshit title). Now that I've watched your video I can see why there are no videos explaining this shit, it's so complicated. Thank you so much for uploading this, I can see it's hard even for you to explain it. Also I'm subscribing.

[@ExtrusionXDesigns]

lmao u dont know how to search properly thats why,

[@randertonyo]

This guy is AMAZING! He takes something VERY complex, and makes it understandable. Thank you so much.

[@davemound5502]

Who knew Kermit the Frog knew about QR codes!! ... ;) Thanks for the info, great vid.

[@lilithdevonrex]

haha

[@weltmeister]

rude

[@VivekYadav-ds8oz]

@@weltmeister but funny nonetheless XD

[@yomama1938j]

Dab

[@zomega4075]

Could make an entire kid's show out of "Muppets teaching"

[@mufmager]

This is probably something that a human can not even fully learn, no matter how much practice he takes on it.

[@Its_Pritam_]

I just implemented a barcode API in an app! Then I was curious about how exactly it works! And here I'm right now!

[@bobanderson665]

Nice video. However it is much simpler and faster to find the characters in the ASCII table if you convert the block pattern direct to the octal values (i.e. no adding up is needed!). For example, your lower case "s" at 18m48s is the bit pattern 01_110_011 where I have separated the pattern into the 2 and 2/3 octal characters with underscores. With a few minutes practice you can just read that off as the octal number 163. Now look over to your ASCII table and there you see the octal number 163 next to the lower case "s". No sums required! There are only 7 octal patterns to remember and you can then translate any number of bits to octal or just do the mental adding up of the 4 plus 2 plus 1 bit values for each character in your head.

[@DinoNuggies4665]

Good idea!

[@nelumboandrews6762]

Great idea but also , NERD!

[@ARP2wefightforyou]

who came over after watching hank green's video?

[@NebulusVoid]

Totally not me

[@stuvs830]

Yeah, but this man uses too many pauses and modifiers that break up the flow. I cant follow his teaching.

[@NebulusVoid]

That's a weird ass name you got there boy

[@ARP2wefightforyou]

Blake T​ me?

[@NebulusVoid]

Levi Langer Lol you're name is too long

[@89nekkoinu]

Hi, Hank Green just sent me here. Its actually really interesting video. Thank you

[@ARP2wefightforyou]

I started a thread about that above.

[@Ddday14]

That's not a thread fucktard.

[@ARP2wefightforyou]

Ddday14 Have nice day. :)

[@xtr33me]

I'm not sure why you stopped putting up videos, but this here is an absolute work of art! Thank you so much for giving us such a thorough video! Well done and hope to see more from you in the future.

[@TheCracker94]

After having seen how to decode a MIDI file, this seems easier to me now

[@casa8017]

Hey man I got a puzzle for you. Can you help me solve it?

[@firz76]

@@casa8017 yeah you are 4 years late

[@christopherf6410]

Yes

[@Redminer9630]

who watches after 20.4.24

[@algodoomarbleracing]

Hi

[@msgcheckout]

Someone to have come up with this QR Code must be bored to death with his social life and had nothing better to do I guess, on top of this, however fewer friends he had, they must have got bored to death with his QR code talk in his local bar. I feel sorry for that guy. But thanks for cracking this stupid code

[@ChunkyROX]

This is the crazy man’s sudoku😂

[@jeffkiku]

I just saw a short program about the Japanese guy who developed the QR code but they didn't say anything about how it worked. Your use of an Excel spreadsheet was pure genius and actually made it understandable. Now I want to read the Wikipedia article to learn more details. Thanks for producing this video. It was both entertaining and informative.

[@numgun]

My mind exploded

[@chrisanders7257]

you upload the spredsheet?

[@andrewwood1502]

still such an awesome video even in 2024 thank u bro

[@clownprince6609]

Thank you for your efforts, you just made me a little bit more smarter.

[@johnnations5932]

More smarter? Quick, get thee to a grammar video!

[@federicobenini8019]

@@johnnations5932 AHAHAHAHAHAHAH

[@SkyewardSword64]

r/ModusOperandi sent me here. Incredibly interesting stuff.

[@DOMiNOUKAE]

Qr coeds for otakus

[@index2560]

human read qr code: 20 minutes scanner read qr code: *beep*

[@cxa011500]

This is a little late to ask, but how do custom QR codes work where they put an image in the middle of the QR code or use a circular shape? Are they just adding random dots around the outside to fit the shape or is that actual data? And are they just covering up the error correction information in the middle of the QR code which doesn't impact the functionality or just are they changing how the QR code data flows?

[@baryhobal]

For QR codes with an image in the middle, it's possible thanks to a high level of error correction. Indeed, with the highest level you can technically recover as much as 30% of the code. So the image covers some data but leaves enough information to still have a readable QR code. For circular QR codes, I haven't personally encountered any before you asked but yes, it's probably just gibberish added to the outside, which makes these technically no longer QR codes since the ISO standards states that a 4-module wide area should be left empty all around the symbol. As for QR codes with non-square tiles (circles, rounded square, etc.), that's not an issue because the reader samples color in the middle of each cell, so as long as the center is more or less black, it all good. (Note that an inverted QR code - that is white squares on a black background - is also readable)

[@anshumansrivastava8108]

I know I am never gonna do this but it was nice to see someone explained it very well which was mystery for me for few years

[@fiber0ptichell452]

Great work on the graphic side, those took some time to create. You broke down the qr in a way I understand now. My reason for reading qr by hand was detailed at the 8 minute section adout over lay patterns, reading directions. Thank you for that. You lost me at 11 thru 13 minutes in video. I encourage all watching this to let it play,, it will come together for you by the end. If you want to understand qr investing 20 minutes here will save you 5 hours watching other videos that only tell what apk to download. This video tells details you can use and apply. Next video will you explain how files are hidden inside image files and how to decode them. FIBER0PTIC / FBR, The HUMBLE Guys, Napalm and Worship.

[@Berkana]

Thanks for doing these videos! These are great. The Wikipedia articles never seemed enough to make these encodings clear to me. Could you do one on Micro QR or Mini QR? I've seen codes which only have one targeting square in one corner. How do those work?

[@Xatzimi]

Any chance for a video about the error correction sections?

[@Pillazo]

+Matt Tycho I'll take a look into them but no promises. Those are some heavy math.

[@Pillazo]

+Matt Tycho Alright, looking for some references, here's what I've found: en.wikiversity.org/wiki/Reed%E2%80%93Solomon_codes_for_coders downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP031.pdf I'll look into these later to see if it's something I can understand and possibly make a video from.

[@auxnull]

@@Pillazo man, you are a champion.

[@danielcoetzee5793]

0:22 "QR codes are actually a beast of a code" or if flipped it is actually "the code of the Beast...!" Know what you're dealing with!

[@rorybranos]

Shut the fuck up not everything is made by satan

[@n111254789]

It's a method of data storage. If you could see what sectors look like magnetically on your hdd it also has a strange appearance. Computers aren't great with image recognition so we store data as simple for them as possible. What looks easy for us is tough for a computer and what is simple for a computer is tough for us. We aren't the same. Nothing to do with religion we just need a way to talk to them quickly. Our interface with machines is a huge limiting factor we are always trying to make it easier. We have a bandwidth limitation that is done by either scanning things or slowly punching stuff in with our fingers. Nowadays talking sometimes. It's all just way to store and talk to a machine it's nothing to worry about you are educating yourself on them though and that's good hopefully the fear of them has relaxed a bit and you understand more of how they work and what they do. It's just a piece of paper or sticker with the ability to help communicate with your computer to make lives easier. You are doing right though by investigating and learning about them.

[@erililil]

One way to make it easier is to start the “unmasking” in the length corner. That way you can know how long the text is and you don’t have to unmask the whole thing.

[@albertgao6929]

There's one error in this video. When you apply the masking, the purple fixed patterns weren't skipped over. They were merely ignored. In other words, for this specific qr code, the grey lines should start from the first line (0th line), and then the third, the fifth (skipped cuz it's fixed pattern), and seventh and so forth.

[@casa8017]

Hey man I got a puzzle. Can you help me solve it?

[@benschofield1361]

Isn't it the 7th line that is fixed not the 5th?

[@Alex-hn3cy]

Internet Explorer... Really?

[@Pillazo]

+Alexandre Boutin Katzmann work computer. My hands were tied.

[@allanreford1440]

+Alexandre Boutin Katzmann It's really not that big of a deal. Such an interesting video and you see that.

[@MultiYippee]

+Alexandre Boutin Katzmann Internet Explorer is much better than you think. It isn't 2004. Stop making that dumb "IE is crap" comment. Not funny.

[@casa8017]

Anyone in here who can help me solve a puzzle? Im looking for someone who can solve it

[@hardikpatel6325]

@@casa8017 i can help...!!!

[@erililil]

It’s 4 AM and I’m learning to read QR codes by hand

[@sololo1391]

Thanks m8! you helped me decode the QR code on my homework so I can read the text of answers! Thanks Dud! I'm 11 Years Old Btw .-. Now no homework can beat meh! Or maybe even school work .-.

[@GabrielTobing]

In the future: A QR code inside of a QR that's inside of many more QR codes!

[@Moosh_fr]

trying to make an algorythm that generates a QR code from a text, thanks

[@queeniefcharles]

hey. I woke up with the obsessive idea to reverse engineer/decode a QR code. I couldn't thank you more for making this video, such a great amount of work, and purely explained. thank you very much

[@GabrielTobing]

6:35 The 4th grey line from the bottom in the right most QR code is missing 1 grey dot.

[@Aerox90]

True! The middle one of the three white squares should be grey :P

[@joshuae668]

I like how you keep saying "don't be scared". Great video. thanks.

[@ninjakiwigames5418]

Today I was thinking I wanna learn to read qr code and well now I'm here

[@danwhaley_]

This is what true content looks like. THANK YOU. Perfectly done.

[@willsmish2837]

Awesome vid. You sound like Kermit The Frog, lol.

[@ponygirl007]

Thanks for sharing this knowledge with us. I have been looking for an understandable method for awhile. Your explanation is the easiest to follow. I will be trying it out on a code I found that I believe unlocks something special. Perhaps I will ask your opinion, as well. Thanks again.

[@WillFaustCuber]

I mean you could just use your phone camera...

[@feiomaskatista]

I don't understand English very well but your explanation was damn good!! Thank you...

[@GabrielTobing]

Life and death situation Person: DOES ANYONE KNOW HOW TO READ A QR CODE??? Other Person: If only I had my phone. Everybody that watched this video: MY TIME TO SHINE!!!!!! I knew that watching 20:10 minutes of understanding how to decode a QR code by hand would come in handy.

[@dangson302]

So boring when you count all the symbols at the end. Anw, great video. Thank!

[@ericktorres9826]

5:50 Didn't get that part. My native language isn't english, so I didn't get it.

[@slimestoneexpert9804]

arnt, there subtitles

[@TheRealOderless635gnat]

Great video after I learn it I can figure out rickrolls or unexpected jump scares

[@rohanghige]

Fantastic... You made the horrifying QR code look easy... amazing video.

[@Yvysanna]

I understood the whole thing, but if I paint my own Code, it doesn`t look the same way, the generator does it in the right corner (just where I know, how to write letters in)

[@jamesoooooooo8389]

Why am I, a 13 year old watching this video for no real reason?

[@Crazytesseract]

It's about Finder patterns and timing patterns and orientation patterns. Then byte pattern and layout. Then there's error correction! So interesting! Error control coding. BCH codes for bit error correction, Reed Solomon codes for symbol error correction. Hope you get it. Hope you loved it!

[@Crazytesseract]

It's about Finder patterns and timing patterns and orientation patterns. Then, byte tile shapes and layout pattern. Then there's error correction! Error control coding. BCH codes for bit error correction (format information only), Reed Solomon codes for symbol error correction.

[@ilhantanriverdi]

Thanks for the detailed explanation. I will of course use an app to create qr codes, but i always wondered how it worked and now i learnt. By the way, how many did you spend to create that excel file? :)

[@RahulChoudhary-qo6qs]

Do you know what a motor is? Manual vs automatic? Winter tires?

[@patzer229]

fwiw you can decode letters without looking up the ascii chart. Ascii capital letters are (64 + letter's place in the alphabet), ascii lowercase are (64 + 32 + letter's place in the alphabet). For example 98 is ascii for "b" because 98 = 64 + 32 + 2, and b is the second letter of the alphabet

[@TheSqualle34]

AND... fun with Excel! Great video.

[@FloIancu]

Thank you so much for this tutorial. I'd been searching for this info the whole day until I got to you and not only did you make black dots understandable, but I was laughing the entire time. Keep them coming! :)

[@elnico5623]

4 bits or half a byte is called a nibble

[@casybond]

I think you made a mistake: When masking, the timing patterns are not skipped over but are simply ignored. If you'd look up the documentation you will find that the modules that need to be inverted are defined by simple formulas that take row and column coordinate as input. The one for vertical lines being: (row) mod 2 == 0.

[@raidenfaden2418]

How did you put the QR code into the excel? is there a way to put it onto a google spreadsheet? i dont have excel.

[@taco-ew4bw]

Thanks Kermit!! Things like this are severely under appreciated! Almost like going back to the beginning days of coding.

[@marn200]

Can I download that sheet somewhere?

[@rolandporogi7243]

Hi! I exported my accounts from Google Authenticator, but the QR code is too complex and will not be scanned by the phone. What is the solution? Would a good camera like an iphone be able to scan? Or is it possible to decode manually?

[@randomexploiterhunter]

With this video, I successfully decoded an actual QR code from real life. Dang, it was hard, but worth it. :)

[@edicted2065]

Can anyone confirm that he did the demasking incorrectly at the top? The demasking process is based on an algorithm. The one he's doing is: ( i % 2 = 0 ) This means if the row is even if needs to be inverted. But he skips the finder pattern row and acts as if it doesn't exist. I'm pretty sure that has to be incorrect.

[@staaaajn]

How come the 'Robomatics' QR code at 0:01 is totally different from the one at 15:44 ? Confuses me enormously.

[@mosesryder4792]

34 People didnt understand Great Video. Thx a lot

[@jungsa4691]

hey, that's pretty impressive. Thank you! was looking for something like this.

[@bobbywasabi17]

is there a way to decode biggger QR Codes? perhaps with different masks? can anyone explain it would be appreciated

[@bharatmadho3742]

where you filled E1 till E 7 are slightly wrong. this data will be filled with some air coming in the form of 11101100 and 00010001. your error correction bytes will start from E8

[@NonTwinBrothers]

When the 20 minute tutorial doesn't even touch error correction, you know you're in some deep shit

[@MygenteTV]

is the a way to decode a qr version 20? I'm trying to find any website online for it but still nothing

[@jonatanmedina5803]

Wow that was a lot of staff. I did a custom QR Code for isolated systems, what means I did my own method of codifying the info to create the QR Code and use it for what ever purpose I want. You can have a look to the result here --> kzbin.info/www/bejne/rJDPZ2OQbNaMf68

[@tito7320]

Barney!!! Is that you!?!? It's me Homer Simpson!! Just kiding ... great video dude!!

[@goldenrevolution5454]

Great Video!

[@danielmarsden4573]

I don't think you're supposed to ignore that row of timing patterns when you damasking the code. On my own attempt that has caused all the boxes above it to be the inversion of what they should be, also the example on wiki implies that its the first layer that is inverted.

[@pierremorena4307]

I have a similar problem, what is this row of timing patterns you're talking about please ?

[@philteng760]

This is the best video explaining qr code I have seen so far. Thank you.

[@charlyxiao828]

Can anyone tell me the URL that was mentioned at about 10:18 ? I only understood qrcode.----.com | thank you in advance

[@jasonspence]

5:34 I'm pretty sure that's wrong, the lines start from the top, where the first row is an even row. Check the wikipedia example image with the wikipedia url, where you can see that in the middle top section, the top line is inverted.

[@asasasas2143]

This is god level , definitely subscribing you. I am watching this video after 10 years since it was created but it is still relevent.

[@Jamato-sUn]

Are you sure the mask line skipped under the timing or not? Some pictures on the internet say it is. I'm fairly sure you applied the pattern incorrectly and just didn't get to the incorrect part by chance.

[@pablogriswold421]

One hell of a hassle! You're a trooper. Masking patterns seem unnecessary to me, but the rest of the code makes more sense now. Thanks!

[@NavySturmGewehr]

You're not kidding about the error correction. The maths... oh my fudge, so beyond me.

[@SorakaOTP462]

thanks, now I don't have to scan QR code when I see it being posted on a wall, I can directly type the URL address on my phone!

[@liuian771]

i'm just wondering where is the 'data' come from . thanx

[@GalaxyCatz]

Ewwwww internet explorer

[@Gasimoe]

Very nice vid! But where can I generate QR-codes that is this "simple"?

[@Samishi64]

Now no one can Rick Roll me now

[@axpers99]

Incredibly detailed video. Deserves a medal:)

[@roelvanassche1317]

if you ever wonder about the total specs: www.swisseduc.ch/informatik/theoretische_informatik/qr_codes/docs/qr_standard.pdf

[@OtherworldlyYTP]

19:34 anyone else hear SpongeBob walking sound effect?

[@mydiascis4517]

try to scan that code on the screen. (first one)

[@technicality]

Anyone else come here from Hank Green?

[@MigsLechon]

watching this 10yrs later, AMAZING

[@premiumboi473]

Great,now I can decode a rick roll qr code, because people nowadays use qr code instead of links

[@GabrielFGomes-ok9qc]

64+32 +8+4+1 = Hard binary code = 109 = m (4+2) + (13) = 6DHex = (easy 8421 code) 6 + D = 6D Hexadecimal =109 Decimal 6DH = (HEX ASCII CODE ) m

[@sunareii]

Finally *knowing that a Rick roll is gonna be next in my autoplay* *knowing a rickroll link even though it’s not the same one* *knowing a rickroll from a QR code even thought it’s not the same* Its all here

[@Raerhix27]

Finally, I can play The Talos Principle without needing a phone.

[@DougieBarclay]

FASCINATING. Who invented this? ALIENS?!

[@joelldeguzman]

is the QR code found in PepsiPXP promo Pepsi diet cans a valid QR code? coz when i tried to scan it with the Neo Reader it's not reading the code... then i noticed that the codes are not in square but in dots...

[@skorpiman5155]

Can you please send a link for all the codes you need to solve it? I am using android (mobile) so wikipedia won't show me all the info.