The RSA Encryption Algorithm (1 of 2: Computing an Example)

[@DJ_Force]

I have a master's degree in computer science, and this is the best explanation of RSA I can remember coming across.

[@DJ_Force]

@@noahr1379 Funny, the diploma on my wall says I do...? I definitely remember paying the bill...

[@DJ_Force]

Good grief, I am getting flamed for liking a video on encryption. Good thing I didn't say anything political, I might be DOXed by now!

[@classicsethposts]

@@DJ_Force I don't think so

[@alwaysinagoodshape5327]

@@DJ_Force Everyone has a lot of degree now the world is warming up. What makes you so special, huh?

[@DJ_Force]

@@alwaysinagoodshape5327 Good grief, what a bunch of snowflakes here. My point was that my formal expensive education didn't have explain this as eloquently as this short, free KZbin video does.

[@mattt2684]

Man... This is the definition of a good teacher. You can explain things very well and in a succinct manner. Great video!

[@glassbat86]

I agree! His students are so lucky.

[@eternal3717]

@@shamsmehdi3725 But not many people can teach as well even if it is just for show. That's the difference

[@umair7280]

@@shamsmehdi3725 sure when this was uploaded in 2014 where he didnt even get a 1000 views...

[@inum400]

@@shamsmehdi3725 I have no idea what "making a numbnut followers idiot" means, but all that matters is that he taught these high school kids a topic, and he taught it in a way which allows anyone to understand it easily.

[@aprilflowers986]

@@shamsmehdi3725 dude shut up, you have no idea what you're talking about

[@ashleypursell9702]

this is the kind of teacher we all needed in school

[@ksxf9876]

If the teacher knows this much why would he be a teacher in school

[@ashleypursell9702]

@@ksxf9876 cus he wants to teach ,,,,,,,,,, LOL, wonder what u know lmao

[@patricklarose]

Now with the internet, he is the teacher we all have.

[@stro999]

On soul it sucks it’s easier to understand as an adult

[@panzonecadutodifaccia]

2 hours of lecture in my uni and I didn't understand shit, 8 min of video and I feel super confident about rsa. Thanks man you a great professor

[@arlo4639]

when a secondary school teacher can explain things better than a tertiary lecturer can, shows just how bad tertiary education is

[@mive5525]

I feel exactly the same lol

[@Mathin3D]

If the two hours of high-level maths did not reveal the intricacies of RSA but you think 9 minutes of an over-simplified example does, you belong to neither Computer Science nor Mathematics.

[@yanna6815]

@@Mathin3D Hate to break it to you but not all teachers are good at what they do

[@tincoyan7380]

Repton Maybe the tertiary lecturer thought you’d learnt it from the secondary school, so they started teaching you something difficult.

[@seanmalone6498]

Not only did I just see the best explanation of RSA encryption that I've ever come across, I got a free yoga lesson as well.

[@matthewchunk3689]

that chinese guy talks like a cartoon kangaroo! krikes!

[@harper5378]

What a good teacher, you can tell the students are actually interested by how they're engaging as well.

[@worldaviation4k]

This makes more sense than some other videos that i searched for in other places with the fictional alice and bob. Proper detail like in this video with the actual numbers is far better than other videos i've seen elsewhere

[@thisistraightgarbage]

I hate Alice and Bob. I know they're a historical artifact, but they don't make the concepts any clearer.

[@smiechu47]

Fuck Alice and Bob

[@pracha95]

They are busy ducking each other

[@michealkinney6205]

I must have watched the same exact videos as you, lol.

[@kl6544]

Alice and bob worked for me doe

[@rish1459]

I love how you simplify the algorithm & solution. Additionally, that was a great homework assignment to show why we can't rely on approximations stored in calculators for irrational numbers.

[@guilhermemarinho3591]

I'm a computer science graduate student and this simple video was worth dozens of hours of tedious lectures. Thank you! Hope you keep the great work!

[@Jinsun202]

Being from Ireland, the first couple of times I heard you say "Irish say" I had to remind myself he's saying "RSA", ha ha. Great lecture, brilliant enthusiasm and clear explanation, thank you! You're not just a good lecturer, you're clearly also a fantastic teacher.

[@DiwasTimilsina]

Why did I not have you as my teacher? I missed out on so much. Truly amazing teacher!

[@josianeumunezero2978]

This Video was uploaded when I was still in high school but here it is helping me out with final-year undergraduate studies. Thank you, sir

[@prithveen7654]

If I had a lecturer like this guy, I would ace every subject! Great job man!

[@Jack-dx7qb]

Some remarks: 1. The public key is (k = 5, m = 14), where 14 is a modulus (often large) chosen by the recipient, and 5 is an unit mod φ(14). Note that 5 is multiplicatively invertible under mod φ(14), and the inverse of 5 is 5 mod φ(14). 2. φ is the Euler totient function. φ(14) is the counting of positive number that is less than 14 and is relative prime to 14. φ(14) = 6 = (2 - 1)*(7 - 1). 3. The private key is the inverse of k = 5 mod φ(14), i.e. 5 mod φ(14). 4. In the video, we use 11 as our private key since 11 is congruent to 5 mod φ(14). We could use any number that is congruent to 5 mod φ(14), i.e. 5, 11, 17, 23, ... etc.

[@danaghafour]

Thank you, I was wondering where 11 was coming from.

[@UnreaL9]

i wish my teacher explained it as simple as you. Great teacher, well done!

[@Jwellsuhhuh]

a unit

[@benterry2681]

You explained clearly in 8 minutes what I couldn't fathom in a 2 hour lecture, Thank you, you're a credit to good teaching.

[@chakkerzo_o8911]

Watching this preping for a Master's degree - so well explained, actually got some insights from this that were not in the University lectures. For a while I was thinking something was wrong, but this actually highlight things in my notes I had failed to appreciate. Good job!

[@mspotato138]

Had to refresh my knowledge on the specifics for a test today. This was by far the best and most concise explanation i could find. Well done

[@zxchtl]

Australia Year 12 Graduate here. For our last part of Digital Solutions, we dove into ciphers, consisting of the basics of caesars cipher, vigenere cipher, OTP ciphers, and eventually RSA encryptions. My issue wasn't the way it works, but more of how to implement it into code. This video helped me develop a C file that could take in a p,q and a string to output an encrypted message, as well as allowing me to decrypt it. Thank you soo much for the headaches you saved me from.

[@fabioschmidt2081]

Every time I don't understand things in my classes in computer science, I get on youtube to find an explanation video about the topic I want to understand. And almost every time I find a video of yours. I like the way you teach and you make it very easy to understand complex things. Keep your work going man, you're great!

[@archeopteryxes]

Eddie, you are a genius. I am a math teacher too, and its incredible how much i learn everytime with your videos. Best of lucks in your life!

[@neosapien247]

The simpler way to do this would be To find 4194304 (mod 14): 4194304 / 14 = 299593.1429... 14 X 299593 = 4194302 (discard decimals) 4194304 - 4194302 = 2

[@alexk6745]

you don't need calculator. 4^11 mod 14= 4*(4^2)^5 mod 14 = 4* (16 mod 14)^5 mod 14 = 4* 2^5 mod 14 = 4 *(32 mod 14) mod 14 = 4*4 mod 14 = 2

[@luislopez-tx4tl]

yaaas queen yaas

[@masonmichalec2942]

@@alexk6745 how do you do this?

[@alexk6745]

@@masonmichalec2942 4^11 mod 14 = (4 * 4^10) mod 14 = (4 * 4^(2*5) ) mod 14= (4 * (4^2)^5) ) mod 14 = (4 * 16^5 ) mod 14 = |as 16 mod 14 equals 2 repace 16 by 2| = (4 * 2^5 ) mod 14 = 4 *(32 mod 14) mod 14 = 4*4 mod 14 = 2

[@Jinsun202]

That's not simpler. It's more complex. You have 5 steps, he has 4.

[@mrjohndoe6981]

I thought RSA meant "Really Secure Algorithm"

[@Matthew-pn1qu]

Lol

[@fobabs]

Lol

[@namaanda5349]

Lol

[@anaibrahim4361]

I wish I had a teacher like you, wonderful explanation, your class is full of energy, you are the type of teacher that loves his job.

[@zackbell3520]

Dude THANK YOU! I had a RSA algorithm problem due at midnight and I would have not been able to solve it without your guidance. Thank you for everything you do to make students lives a little easier.

[@ΜιχάληςΚαστρινάκης-χ7κ]

6:40 it would be easier if you divide 4194304 by 14 which equals to 299593.14... then we take the integer part (299593) and multiply by 14 which is equal to 4194302.. and now if we subtract 4194302 from 4194304 and we get 2 which is equal to number B

[@drewshepard6989]

haha exactly what i was thinking when he was doing the video. The reason he got the 1.999 is because when he did the division he got a repeating decimal and you cant really multiply a repeating decimal the calculators got to chop the number off somewhere.

[@ArjitGuptaAG]

just worked it out on 88^7 mod 187(william stalings example).... works like a charm. Thanks man

[@Exachad]

Exactly what I was thinking!

[@akibmahmud3744]

What will be the calculation for (1/17) mod 60 ? ( Ans: 53)

[@3kelvinhong]

It is not easy for our brain, we can easily memorize .14... Then multiply 14 we get 2, very fast and efficient enough

[@ethanpillay9063]

I have doctorate in math and computers and this is the most succulent explanation on the whole internet

[@lordfresh]

I am an actual professional security expert and this explanation is excellent.

[@MissNorington]

Never before have I seen such an easy explanation of RSA (online)! You are a good teacher Mr Woo!

[@heromiIes]

These students are getting a real treat with this teacher.

[@ProfessorDingus444]

it sucks to watch a great professor that is talented and knows how to educate be disrespected by his students like this. I learned so much this and I appreciate all your diligent work !

[@Kregexx]

what did his students even do that was disrespectful? they were asking questions.

[@urwasheikh1343]

Guys I think the reason why the calculation does not give us 2 and instead gives a very long decimal 1.99999999988... is because when we divide 4194304 by 14, the answer actually is 299593.142857142857.....(I divided manually using long division), but in the calculator we get a rounded figure of .1429. If you multiply 0.142857142857.... by 14 (instead of the rounded figure like he showed), you would get a proper 2 instead of 0.999999988.... So, it happens because we round figure the decimal number and not calculate with the actually long decimal that we get when we divide manually by long division on a notebook.

[@dauphinguillaume28]

I miss school so much when I see this kind of topics handled by a great teacher

[@luuk8426]

This is exactly what I was looking for, makes so much more sense than all the other explanations combined.

[@bertmarshall5459]

I was amazed at how simply you were able to explain the RSA process. After walking through this process a few times of compute the keys for e=2, d=7. I follow Mr. Woo’s suggestion test you understanding by calculating the keys for e=3, d=11. Mr. Woo I would like to suggest you make a third video that uses e=2, d=7 than encodes and graphs the number in order from 0 to 28. I believe this should result in a waveform that repeats every 14 counts. Then challenge you students to graph the waveform using e=3, d=11.

[@klevdavful]

Epitome of a good teacher even a newbie can grasps and with enough reps can develope encrypt decrpt skills.

[@freejohn]

There are many videos out there that explain the concept of public and private key in a simple way, but I always thought they were too "abstract". In my opinion, this here is a really good explanation that makes you grasp the concept in a better way, because it "dives the right amount of deep" for a initial explanation.

[@countryconnoisseur_]

1 day off from being exactly 10 years ago... Video still holds up!

[@AlienX-p2f]

I love your enthusiasm and a different approach towards the topic. VIVA!!!

[@Vincent-lg2jh]

I have ADHD and Im having so much trouble with my computer networking course because of how boring it is. But this guy kept my attention, Thanks

[@SIGSEGV1337]

Dude you're a great teacher, you seem genuinely enthusiastic

[@AnubhavApurva]

Never realized it is so simple. Text books make it so hard to understand! Kudos!

[@danzmd]

You made something that seems super hard become super easy, thank you!

[@TheProjekton]

+Daniel my It is easy when dealing with small numbers. When dealing with 4096 bit primes it becomes much harder to solve.

[@faisalalan8633]

In real life, the modulus is very long! probably 50 hexa-digits long!

[@赵沅]

The way you teach is really amazing. Really amazing.

[@maheshiyatipansalawa3383]

we all need this kinda teacher. He is good at explaining and is funny.

[@baijokull]

I love that when I have a teacher that is not as good at explaining stuff I can just come to youtube and find a better one. What a world we live in :D

[@YuNgHaSaN]

He seems like such a genuinely nice guy. Thanks for the clear and understandable explanation Mr Woo! :)

[@lisazilm3781]

This is the best explanation I have seen! You're a good teacher!! Far out!

[@RakhiDhavale]

This teacher is a amazing with his teaching skills 👍🏻

[@mahdizarepoor8964]

woo woo you are awesome . now im in second term of university and im studying Software engineering but wish i has teachers like you in school . your explanation is great and I really appreciate you . i wish you luck .

[@krunokartus5382]

Great to listen to him even if you are not familiar with the RSA :)) I desperately needed this, thank you Eddie

[@UnmaskedX]

Dude, I literally have a test on this in like two days. You are the best

[@SpiritmanProductions]

Why are people talking while he's teaching? I don't understand.

[@malhibhai5888]

your absolutely incredible. idk what it is about your teaching but it just works

[@polyesterdreamboat]

I'm a real idiot when it comes to math. This is the only video on RSA that makes any sense to me. Thanks Eddie!

[@tomaszgorka7542]

Have to say this, you saved my life, that's the best explanation on the web and I have to do this as a homework for tomorrow, thanks!

[@meinland4439]

wow what a great teacher! love the enthusiasm, you can tell he's very passionate about this kind of stuff

[@arthiudayakumar4000]

Its really a good and simple teaching which help millions. kudos

[@niceguy091000]

a - b(floor(a/b)) is a nice way of calculating modulo.

[@BradBo1140]

He just hurt my brain but I see a tiny light of understanding way out on the horizon. Math guys and gals are awesome.

[@soundhargs7363]

Oh man! The way you handled yourself is awesome and the lecture was so clear and perfect one i have ever seen!

[@quantumscapegoat]

I really cant describe in words how f***** AWESOME you are man. Ive been watching your videos since year 10 and now im in college, watching this video to clear some concepts in Quantum Computing. Thanks Eddi

[@moctar1001]

The best RSA explaination i have ever seen

[@Murder1nc]

Wish I had a teacher like you man holy shit. I was confused till I found you. GGs only wasted 1 day trying to figure this out and boom in 8 mins im a God at RSA crypto.

[@mohammadomar2954]

u r the most conistent utuber i guess, who post video almost every day... huge respect sir

[@sss_says_snek]

do you mean consistent?

[@DeliriumX11]

Hi Eddie, I know this video is a few years old but thank you so much. I've struggled a lot with this from watching other videos and reading about it online. This video made it so easy to understand, thank you!

[@abdulbasithmiah9133]

Thank you so much, Eddie Woo. This is helping me for my Uni exam next week. ;) 👍🏻👍🏻👍🏻

[@anishkrishnan9698]

For anyone wondering about the exact details, the sender picks 2 huge distinct primes, p and q. The pair (p,q) is known as the private key and is only known to the sender and the receiver. They then define n=pq and work out φ(n) = (p-1)(q-1). φ(k) is the Euler Totient Function which is the number of integers between 1 and k which are coprime to k. Then the sender picks a number e such that (e, φ(n)) = 1 (e is coprime to φ(n) under this notation). The sender then publishes the pair (e,n) (or (n,e) in some conventions) and this becomes the public key. They then send a message by converting it into a number M, with M

[@shadmansudipto7287]

Hey since you commented recently lemme ask you, why does he put mod 14 even on the answers? Like 32 mod 14 = 4 mod 14?

[@dwaynejohnson6264]

I love how digestible you made this for someone who has no idea about RSA!

[@LITHIUMINWATER]

This is brilliant pedagogy. Thanks.

[@funkycivilista6191]

Finally someone who get's straight to the point. Thank you!

[@681726]

Maths is too hard, I'm gonna doing some yoga.

[@shariulhashmi6343]

nice name

[@nayeem9236]

How's the yoga working out

[@Ken.-]

I was sure that sentence would end with drugs.

[@izzyr9590]

literally gonna comment Yoga lol!. its the first thing I noticed. weirdly fits.

[@quoipi]

Are you enjoying your yoga?

[@igorordecha]

If you can record your lessons, upload to KZbin and pull off nearly a million views, you know you're a good teacher.

[@michaelhoffmann2891]

Man, this brought back memories when, for reasons unknown, YT put this in my feed. Made me remember the demo program with a silly little Windows Forms interface (hey this was over a decade ago) I wrote during my Master's at Monash and have a look at the old source code. Had to do it with "classical" random primes and then also with elliptic curves - and included Diffie Hellman for key exchange. It showed all the various steps including the "magic" going on in the background. Was one of my favourite units (and got me a HD ;). How I wish I'd had teachers like you so we would have done this in high school!

[@zhaoxunyan4016]

The "lock" analogy is much better than the "public key" terminology. I came up with this idea soon after I learned the RSA and I am not alone. I wonder why they have not changed the terminology yet?!

[@srutikeerti1297]

Loving his approach and enthusiasm of teaching! Thanks a ton! :) you are an amazing teacher!

[@michealkinney6205]

I know it's just a demonstration but working out both (4**11)%14 and (4**5)%14 are 2 (or the original B), so you can "decipher" with either. And there are several other ways to reach the same answer, but also a pattern actually emerges (mod remainder 2, 8, 4, repeat). But I imagine that the actual math behind the algorithm is much more complicated. Thanks, cool video.

[@mitchelljones6179]

I thought leaving high school would be the end of watching Eddi Woo but turns out he is better at explaining this than my lecturer.

[@madaweehathloul2045]

i love you , i thought my last math course was the end of us but here I'm

[@terox3920]

love it, the best explenation so far

[@christophercabo3924]

it gave me two. lol - You're my favorite mathematician now!

[@un1c0rn52]

2 minutes in and I am already extremely jealous of these students.

[@bassamodaymat8329]

Really loved your video and explanation. I would like to say just like any other student watching your video, keep it up.

[@AkashLankala]

I have a final on this in a few hours so praying that you just got me through it!!! 🙏🏽😌

[@lutzweb]

Great explanation and great teacher! Congratulation

[@seanki98]

Eddie is such a brilliant teacher that he has to sush his students because they are busy talking *about the lesson*

[@scubadottech]

Eddie, I just wanted to say THANK YOU! This video taught me more in 8 minutes than I was able to figure out in 2 hours trying to decipher (hah) my textbook. Stay awesome. :)

[@JoachimKessel]

Brilliant, I just love how you took this one on.

[@jensonjoseph6296]

I wish I had got interesting homeworks like what you gave

[@cipherbenchmarks]

Brilliant teacher.

[@joelfrojmowicz]

What an amazing teacher!

[@Eggsr2bcrushed]

Shame such a great teacher is stuck with students who don't seem to care or see the significance.

[@mrarduino2977]

These children seem very well behaved compared to the school I went to, also I think most of the talking is to do with the subject been taught, they are still really lucky to have such a good and respectful teacher.

[@VishalBondwal]

I went through this video pair on RSA at least twice during my Uni days. Now watching more recreationally. Only today do I notice that there's a Yoga poster on the wall. Guess when doing Uni assignments, you are really focused on the content :D

[@MilciadesAndrion]

This is a great and very explanatory video.

[@luislargatinaz277]

Wow quite funny the date of the video and the date I’m watching this, lol. Anyways, that is a pretty good explanation, thank you!

[@ranad2037]

How energetic and exciting! Thank you a lot!

[@cbhansingh1]

Students in this class aren't realizing that this content might go viral someday.

[@lucychioma5293]

YOU are in deed a good teacher

[@arafatalgazaly3489]

great teaching . at all very clear

[@aram5642]

More on cryptography from Mr Woo! Mr Woo is salt of math. I have finally *understood* all that struggle to find bigger and bigger prime numbers

[@intellectualhybrid2]

Eddie, you helped me pass my Codes & Codebreaking Unit at Uni. Thanks!