How does public key cryptography work

How does public key cryptography work - Gary explains

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Күн бұрын

How keys are distributed is vital to any encryption system. Find out how to do it with the Diffie-Hellman key exchange and using public-key cryptography. Find out more: goo.gl/qI6jxZ
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Пікірлер: 198

@kamalphukan15 3 жыл бұрын

This is, without any doubt, the best explanation video on KZfaq on this subject. Thanks a lot.

@markod3957 Жыл бұрын

wtf, this had no business being so well explained and suitable for academic consumption. Great job!

@JimProng 5 жыл бұрын

About a year ago I said, this is the best explanation of public key cryptography on the WWW, and I've still not found anything better.

@samueltarley4828 7 жыл бұрын

wow this guy is better than my information security professor

@zes3813 3 жыл бұрын

@ChrisWMF 8 ай бұрын

I've seen other videos that explain it but don't explain the part about prime numbers. This is so much better.

@hrithik5016 7 жыл бұрын

I seriously wish my teachers knew as much as you do man!

@ervinlabadero23 5 жыл бұрын

At 0:48, the big question is "How does the other party get to know the key?" At 6:15, you said, they both previously agreed on a one-way function. If they are also from different parts of the world and don't know each other, I am now wondering "How does the other party get to know the one-way function?"

@_mickmccarthy 4 жыл бұрын

I realise this comment is a year old, but in case anyone else has the same thought. It doesn't matter if everyone knows what function you're using. As it's a one-way function, you can't figure out the input from the output. In fact, most of these are open source meaning you can go look at the algorithm and inspect it.

@lamensquare 3 жыл бұрын

@@_mickmccarthy Kerchoff principle

@axelfzurital 7 жыл бұрын

This video was awesome. I never thought modern encryption worked that way. I really learned a lot from both of your videos.

@KushagraJuneja 7 жыл бұрын

Faith in learning gets restored when he says, "let me explain"

@1963VLM 3 жыл бұрын

I was searching for 4 days to find such a clear video like yours......!!!! thank you...!!!😊👍

@sikz26300 3 жыл бұрын

Thank you so much! I just spent an hour searching for this example, this is the first video that actually covered the part I wanted to understand, how the data is actually manipulated. Thank you!!

@hrmfa 7 жыл бұрын

Thanks Gary. Much appreciated, even if it's quite complicated. 👍

@SrRunsis 5 жыл бұрын

You are an expert explaining! You even took care of the small details that no one explains! Thank you! In 15 min u explained me something i couldnt understand for hours

@matanissler 7 жыл бұрын

Thanks to you I understood better how public and private key works! Big shout out to Gray who he keeps working on these technical videos even thought they take a lot of energy to make and they aren't the most popular.

@pranavvij 6 жыл бұрын

This is one of the best ever videos explaining public key encryption. Thanks a lot!

@JimProng 6 жыл бұрын

This is the best explanation of cryptography I've come across. Thanks.

@petermainwaringsx 3 жыл бұрын

Best explanation on this subject ever. I keep coming back for another look, change the numbers for ones I chose, do the math and find it always works. Trouble is, I still don't know for sure how! 😜 Thanks Garry.

@brehdem 7 жыл бұрын

Good video, I really like the detail you go into. I studied cryptography at uni and all those formulas brought back memories

@Motwera 7 жыл бұрын

Quite useful as a summary for some of my ISS classes :p

@Lazylion572 7 жыл бұрын

Love your videos! I have used them several times when writing papers for school. Your videos give an in-depth understanding to the subject. Learned so much from watching your videos though i do wish they were a bit more entertaining since the subject can seem a little um...dry sometimes. Anyways keep up the good work cant wait to watch the next Gary explains!

@bobbybenyard6246 5 жыл бұрын

Thank you, Gary. This has helped simplify and explain what could have been a very complicated concept to wrap my head around.

@verkanica 3 жыл бұрын

When he said: "Here comes the magic". It truly was a magic, cause I didn't have clue how he did it!? :) Great Video and the content! It took me 2 attempts to unterstand everything, and when someone asked to explain how Public and private key concept work I was stuck. My answer was: "check it on KZfaq, then we can talk about it" Thanks for the video!!!!!!!!!!!

@davidlawrence8085 3 жыл бұрын

Outstanding on public-key ....thank you much!

@sikmann 2 жыл бұрын

Thank you Gary for dumbing it down. Very informative.

@ameyagonal6657 4 жыл бұрын

U r a hero but I suggest u to make seperate videos for seperate encryption methods so rhat we can understand much better...🙏🙏🙏

@mr88cet 5 жыл бұрын

Aha! I honestly can’t recall whether I’ve heard the exact, specific mathematics behind RSA before. I knew and/or inferred the general gist of it, but it’s great to see the nuts and bolts spelled out here! Thanks.

@francescofreddi4374 2 жыл бұрын

i understand a lot of concepts in only 15 min... after 5 years :)

@aqdhdzwty4132 7 жыл бұрын

Gary is the most knowledgeable guy on Android Authority.

@water1051 2 жыл бұрын

Best explanation I have ever found. Thanks so much!

@fersunk 7 жыл бұрын

I love this kind of videos... Very informative and easy to understand

@rodrigovianna2 7 жыл бұрын

Thanks for "part 2". Really great!

@mr.mxyzptlk6233 7 жыл бұрын

Had a theoretical math in computer science class in college about 2 years ago. Man that was a lot of fun.

@fuzz33594 7 жыл бұрын

Prof. Sims - you never disappointed. Thank you.

@gabrielkotani180 7 жыл бұрын

great video, came on the perfect time as I was looking for cryptography. would be awesome to have other videos like this

@KartikGajaria 7 жыл бұрын

Thank you very much Garry for making the second part. It was really useful... ;)

@Anthony-xr6zo 7 жыл бұрын

Excellent video. So elegantly explained. Thank you.

@ankithguzz 7 жыл бұрын

Very informative. Thank you for making a part two on cryptography. ^_^

@GarySims 7 жыл бұрын

I am glad you liked it.

@ankithguzz 7 жыл бұрын

+Gary Sims I know it's not really android related, but could you please make a video on blockchain technology used in bitcoin transactions? I think many people don't fully understand how it works. Thanks :)

@Bhatakti_Hawas 7 жыл бұрын

Yea a video on bitcoin, how it works etc etc would be nice

@javierperez2609 3 жыл бұрын

This video is amazing. Thank you so much for your work!

@mariaisabelmartinezcastill4438 4 жыл бұрын

THANK YOU SOO MUCH IT WAS ALL I NEEDED TO COMPLETE MY INTERNAL ASSESMENT ON MATHS

@highlander1531 7 жыл бұрын

So informative really, but so confusable. Sir you did great job with this video. thanks.

@1963VLM 3 жыл бұрын

I think you have a natural talent...!!!👍👍👍👍👍

@entertainity 3 жыл бұрын

Amazing explanation!. s the document with the detailed explanation still available somewhere? the link in the description unfortunately doesn't work (anymore).

@8982601240 4 жыл бұрын

Thank you for this quality information. Please tell us about token systems as well.

@stupossibleify 6 жыл бұрын

Excellent explanation. And nice to put a face to Android Authority

@AAYMF 7 жыл бұрын

Excellent work.

@vuongbinhan 7 жыл бұрын

Could you have a dedicated video for hash encoding such as MD5? Btw, this video is great !

@MrHotheadalex 5 жыл бұрын

😯😯😯😲😲😲 my mind just blew away.......amazing ! N bravo u just explained such a complex concept in just 15 minutes amazing

@ivonsim2522 5 жыл бұрын

I like this explanation! it clear my doubt!

@csbhaskar 7 жыл бұрын

I would have given a hundred likes for this! thanks Gary!

@tazeemn 4 жыл бұрын

The best explanation ever!

@brahimchebli7781 3 жыл бұрын

Daaaamn ,The best explaination i ever seen for RSA , thankss

@AnilBind 6 жыл бұрын

Just awesome

@Chameleonit 7 жыл бұрын

Thanks for refreshing knowledge :)

@CharlesVanNoland 7 жыл бұрын

There's a mistake on the Diffie Hellman example with the larger numbers that flashes @8:14. Where it says "2087^8001 (mod 7703) = 6265" it should be '6256' like it shows everywhere else :) I had to use my own bigint calculator program I wrote a while back to figure out which number was the correct one.

@NeonWafflez707 6 жыл бұрын

Yes I noticed that too! Thanks I’m not alone

@xscorp382 5 жыл бұрын

I rarely comment on any video. But this video was just awesome

@octavianomenezes856 5 жыл бұрын

Hi Gary, just one doubt. Try to solve the function could demand a lot of computational power, but taking your example of "H" (72) =13. Someone could use brute force and test a lot of numbers (from 0 to 100) using the public key until find the same encryption result. Someone will not solve the function but will search for the input that gives the same result. In this case, the computational power would be less than necessary to solve the equation?

@paeyreyes 4 жыл бұрын

Thank you for explaining this!!!

$@refractedphoton$

@refractedphoton 5 жыл бұрын

Really good video. Thanks so much.

@Sleeping-nomad 7 жыл бұрын

Thanks!

@thebudkellyfiles 6 жыл бұрын

This is excellent. Thanks.

@micsan381 3 жыл бұрын

Brilliant explanation. 👍👍👍

@bariswheel 2 жыл бұрын

Really great explanation thank you !

@exchange4918 3 жыл бұрын

Good job mate

@floordust83 7 жыл бұрын

Much kudos to you sir!

@Torterra_ghahhyhiHd Жыл бұрын

Question pls the number e=7 and d=247 are those const? are there some special selections of e and d? dependencia in de message or primer number?

@jonassteinberg3779 6 жыл бұрын

Keys are typically 2,048 or now more commonly 4,096 bits, not 248 and 496. He just misspoke, but in case anyone randomly reads this : )

@johna3909 7 жыл бұрын

Great video! Can we please get more of these videos?

@GarySims 7 жыл бұрын

There is a playlist!!! kzfaq.info/get/bejne/qNWVjdZeyrKRnKs.html

@Impostleable 5 жыл бұрын

So with the asymmetric encryption it's encrypting the communication from Bob TO Alice, but how does she communicate back securely? Does he give her a public key to talk back to him decrypting the message with his private key?

@hugohell8290 7 жыл бұрын

nicely done 😃

@NevaehBeatez 7 жыл бұрын

The public key cryptography part was way too complicated but thanks for trying to help my small mind understand lol

@progtom7585 4 жыл бұрын

this was brilliant, thanks!

@francoolayat.3731 6 жыл бұрын

Nice !

@abdullahmoiz8151 5 жыл бұрын

Very informative thanks a lot

@SlayerFoxX 3 жыл бұрын

Great video

@Jose1maneZ 6 жыл бұрын

great video! thanks!

@rmsoft 7 жыл бұрын

amazing guy, great video.

@thememace 3 жыл бұрын

since the dynamic shortened link above is broken. Here's the working one: www.androidauthority.com/public-key-cryptography-717863/

@obsidiansiriusblackheart 7 жыл бұрын

About to go write my exam on this stuff lol thanks man

@techtranslated8218 7 жыл бұрын

Wow very informative and interesting!

@manuelc3671 4 жыл бұрын

Sorry if this question has already been asked, but I'm trying to figure out how to calculate D (12:52), I've tried to use my calculator for it but it tells me that D is 0.142857 and not 247 and I can't figure out why. Any chance someone could help me out? thx

@seddikreghis2589 7 жыл бұрын

Hello Gary sims i really like your explains and all ur vids and i was thinking if you could make a video about cicada 3301 have a Nice day :)

@dinkarchaudhary8858 4 жыл бұрын

Very quick and informative. But considering RSA..... How was the "D" achieved? Thats the link missing.....

@rianp1300 7 жыл бұрын

You posted cryptography videos just when I take cryptography class this semester

@rianp1300 7 жыл бұрын

and yes, Alice and Bob does exist

@navjotsingh2251 4 жыл бұрын

Rian P there are two people in my class called Alice and Bob, my lecturer literally gets them to stand up and go to the front for demonstrations. LMAO.

@Dan-tg3gs 3 жыл бұрын

what are some common use cases for this kind of cryptography? Is Diffie-Hellman the most widely used by all encryption applications?

@Typestyle 7 жыл бұрын

The algorithm Y^X(modp) is shared as the public key revealing Y and P's value to all. Supposedly the attacker has private key He also would be able to decode the message since Y and P values are known to him, right??

@AB-gd8hn 7 жыл бұрын

Referring around 11:52, when Bob wants to send 72, he sends 13 because 72^7 mod 323 = 13. But in addition to 72, there exists another number N such that N^7 mod 323 = 13. So when Bob sends 13 how will Alice know if Bob intended 72 or N ?

@KookoCraft 5 жыл бұрын

A B the key determines that

@xceeder 7 жыл бұрын

Hey Gary , I have an idea for a video which I would love you to do , it's about ram management in android I have the oneplus3 with 6gb of ram however the iPhone 7 only has 2 or 3 why or how does the iPhone have so good memory management please enlighten me....

@xceeder 7 жыл бұрын

oh damn I didn't read the comments before writing mine I didn't know everyone else was asking you to do a certain subject it's fine if you choose a different subject , it always just makes me wonder how the iPhone is so good with memory , is it an Android/Linux problem and can Android ever get their ram management as good as iPhone maybe I'll never know , I'll still watch your videos no matter the subject you are very clever ....

@xceeder 7 жыл бұрын

how do you know that buddy , I always believed it was the ram that they could utilise really well ...

@xceeder 7 жыл бұрын

okay thanks for the info buddy....

@MarcoS-bf9tv 7 жыл бұрын

Android uses Java which is garbage collected - this means that the runtime will keep pausing after set intervals to clear memory. Java itself needs a much heavier runtime since it uses a virtual machine to execute. iOS uses Objective-C and Swift which do not use garbage collection and has performance similar to C, so the result is more efficiency.

@xceeder 7 жыл бұрын

Cool , thanks for replying buddy...

@pedrocoutinho6931 6 жыл бұрын

thanks

@_uditsingh 7 жыл бұрын

There's a reason why you use the name alice and bob. I forgot the story behind it. Can you explain???

@petrslavik1215 6 жыл бұрын

Because Alice can be shortened as person A and Bob as B

@tejara01 9 ай бұрын

@12:04 If I was Eve, I could see a) the agreed formula M^E(MOD N), b) Alice's key ( N - 323), c) the agreed E value (E - 7) and, d) what Bob is sending (13). Therefore I know 2 of 3 "unknowns" and can solve for it. Am I missing something??

@rohitsamleti4865 5 жыл бұрын

Hello Gary, the video is awesome but I have a question regarding DH key exchange...In this video you mentioned two values Y and P to be 7 and 13 respectively...so how Bob and Alice agrees on these same values...?

@pramodchoudhary2136 3 жыл бұрын

any answers?

@hichamtribak1944 6 жыл бұрын

The FunctionY^Y(mod P) must be known only by Alice and Bob?

@pramodchoudhary2136 3 жыл бұрын

How they know it without sharing, and if eve get their hands on this, isn't similar to getting access to keys?

@gigi9876 7 жыл бұрын

nicee, thank you

@KrishanBhattacharya 3 жыл бұрын

good video. thanks.

@howtoandroid7523 7 жыл бұрын

So how does the exchange of Y and P work? I mean, if it's a public algorithm you can simply insert the results of Bob and Alice send between each other. If not, Y and P are exchanged unecrypted...

@GarySims 7 жыл бұрын

Y and P are public knowledge and it doesn't matter if they are know. There are an infinite set of numbers that result in 4 when plugged into the formula and Eve can’t tell which number it is. For example 7^22 (mod 13) also gives 4.

@Freddy3792 7 жыл бұрын

I thought I missed this as well.

@howtoandroid7523 7 жыл бұрын

Oooh, I thought they were inserting 4 and 10 as X and not as Y. Thanks for the answer. I should listen more careful next time :D

@GarySims 7 жыл бұрын

There is also a written article linked in the description, you might find it useful for reference.

@tarunkundhiya102 3 жыл бұрын

anyone noticed the answer 7691 X 5737 is visible @4:28 :D

@theoneyoudontsee8315 7 жыл бұрын

True mind bender!

@rikenm 6 жыл бұрын

I have been searching one question everythwere. Where can d(aka secret key) be stored in android? I saw people saying people can root and just read the key.

@pramodchoudhary2136 3 жыл бұрын

How Alice Bob communicated Y^X(mod)P with each other, what if the eve got to know about this?

@DeputyDawgAtl 3 жыл бұрын

Ok what i'm still tripping on (Using Alice and Bob in my example) - I get that Bob's public and private key are mathematically linked. However if Alice is across the globe how is her public and private linked to Bob. So as I understand it, Bob will use his public key to encrypt a message and send to Alice which she uses her private key to decrypt. OK i'm fine with that. But how is Alices private key linked to Bobs key? If Bob wants to send another msg, say to Tom - again he uses his public key to encrypt. Tom uses his private to decrypt - how is Tom's key linked? I'm missing something super basic here. Any help appreciated