Cryptography/SSL 101 #1: public, private and symmetric keys concepts

The first in the series of videos which will hopefully explain the key concepts around Https and SSL encryption, hashing (Sha 1, Sha 256 etc) certificates etc. I am then planning to extend the series into other interesting related subjects like blockchain and Bitcoin.
If you have any questions or requests please feel to ask in the comments section.

[@Ones_Complement]

Well and beyond the best explained and most effectively communicated intro lesson on PKE I've seen on the web, hands down. Educators like you are an invaluable asset to society, and you have my ultimate gratitude.

[@Nugeorge]

This is an INCREDIBLE explanation of the topic. Real shame you stopped making videos.

[@kartiknit1]

simply awesome. finally a video which clearly explains. love the analogy! thanks for this!

[@MattThomasLondon]

awesome, thanks for your feedback

[@iwswordpress]

Very good use of real non-computer world example. Helps me to undestand it. Worth the length of time.

[@makkar1610]

the best video series on SS/PKI on entire internet

[@johnferrara392]

I've read a dozens of articles and watched dozens of videos for years and this is the best explanation I've seen. I love the analogies.

[@pchebbi]

Mr. Matt Thomas, fantastic videos! I a amazed by your depth of knowledge and the ease with which you explain these concepts which are generally considered as dry and cryptic. I am going to follow your video series in a sequential manner. Thank you so so much!

[@AnupKumar-wq2qc]

Well done Matt .There is no better content on youtube than yours on this topic...

[@MichaelRyanEpley]

Matt, Excellent job! I just finished your presentations on Cryptography/SSL 101. I have zero complaints. You are concise to the extent your subjects allow. Your information is presented sequentially such that I knew what I needed so that I could comprehend the next lesson. Lacking previous experience with this subject, I can only say it appears to me that you hit every lick along the way. The little bit of repetition in these lessons was helpful and allowed for greater understanding on my part. Lastly, I do not see how you could have presented this information any better than you did. I just wish some of my college professors had had your ability. Very well done! Thank you, Ryan P.S. While you made one "mistake" in discussing the use of public and private keys in lesson #3 or #4, as the comments indicate, you cleared it up later.

[@HimanshJainYTube]

Having watched many short videos and understanding nothing, I'm deeply grateful that you made this video.

[@sauravshukla1]

This made me smile.This is how one should teach.

[@UhOohSpaghettiOs]

I usually don't feel the need to press 'like' on good videos. But this one deserves it! Very well explained

[@michaelallen1843]

Matt: thank you! best hour I ever spent alone in a quiet room with a cup of coffee :) looking forward to the rest of the series

[@joshuacmorgan]

YES! Well worth the time. I spent triple the length of this video trying to understand this topic from other much shorter material.

[@HackMac74]

Great tutorial ! Don't you excuse for it's length...the detailed description is in fact the very benefit. I didn't understand the "putting a symmetric key into the asymmetric box" thing before...well done, mate.

[@MattThomasLondon]

Awesome

[@pancratiuschuba6652]

you just won a subscriber. The best explanation on KZbin. Seriously, that was excellent. Keep doing what you're doing!

[@sempieros]

It's a long but at same time briliant tutorial! I do not often write comments/give likes to the clips on youtube but this one deserves it :).

[@cristiano1320]

This video is absolutely fantastic. Simple, but very thorough explanation. Congrats.

[@th3burg3r99]

Awesome video! I went from never studying this at all to feeling like I grasp this concept pretty well

[@erickramirezvargas5538]

Incredible explanation, so clear. You have a natural talent to explain complicate things into really simple stuff

[@sanjeewamaduranga8199]

Complex subject explained in an amazingly simple analogies !!! Great video. Thanks for your time & effort. Much appreciated & please add more videos further.

[@MMABeijing]

gold! your videos are an incredible gold mine! thank you so very much for sharing your knowledge with so much pedagogy. You really tried to understand the whole thing and it shows powerfully when you explain it...

[@newname958]

Hi Matt, Thank you so much. Thank you so much. You have explained it very clearly.

[@martonlorand]

This is an excellent explanations of symmetric and asymmetric encryption . Good analogies with humpty dumpty , evil courier and bank .

[@Fa8103FaLaLa]

Thank you so much for your sharing. This was really helpful. You could describe such a complex topic in such a clear and understandable explanations. Amazing!

[@patelmahesh80]

Matt - After going through multiple videos found your video and you made it easy to understand. Thanks!

[@boogiywoogiy]

Really good, explanation for this is a tongue twister in itself (whatever videos I have seen, by the nature of this subject), but you have done a tremendous job of explaining each bit and also keeping it all together as well - great work and THANKS!!

[@conaxliu9677]

Whew! That was long! But I do understand more about the difference between private and public key now. Great!

[@mohitdahiya3102]

Yoy are amazing mate. Thank you for this video. Now, going to watch your next video.

[@rajeshramachandran1541]

Excellent and clearly explained with analogies. One the best videos on SSL

[@danielmehari2276]

Nice analogy, you made it very easy to understand the SSL/TLS protocol. Kudos!

[@sacintha]

Awesome is the word. I guess you are a genius in what you do.This can be seen in the way you have simplified things with passion. I'm a fan

[@MattThomasLondon]

I wouldn't go that far, but thanks for the kind words. I'm glad you found it helpful

[@RajaPandianCRP]

Hi Matt, been looking for a video that explains SSL concepts in practical terms and finally got this one as a "recommended video". Really worth watching...Thanks for sharing your knowledge :)

[@pthube]

Beautifully explained the concept of public and private key and overall how it works..

[@mrm12325]

Matt, This is amazing man. Your way of explaining is unbelievable. I am a fan now. Thanks lot.

[@MattThomasLondon]

Thanks a lot, hearing feedback like this definitely makes it worthwhile.

[@TheWilloutte]

This video I think deserves more audience ;)

[@mnemotronic]

Thanks! This helped me to understand what was going on "behind the curtains" with all the encryption stuff. There was some repetition that could be eliminated with anther take. OTOH now I know the concepts and use of symmetric v. asymmetric and why we need both. Also the page showing the actual formulea for one-way encryption was pretty cool.

[@MattThomasLondon]

Thanks, yes, it's tough to strike the right balance between sufficient repetition to consolidate the message and tedium, and one will always get it wrong for some since everyone has their own speed of learning. The overall objective is that most people from whatever background who watch the video will get comfortable with the material.

[@samyan24]

Superb explanation and analogy! Literally have not understood this topic better - Thanks :)

[@akimalam2041]

This is a great video. I had some basic understanding of this; however, I learned a lot watching this video and clears many of my confusions. Thank you so much for your effort putting such detailed video. I salute you. Thanks

[@MattThomasLondon]

You're very welcome!

[@sofiahoac]

Good analogies and clear explanation of technical concepts. Found myself with strong feelings of dislike for the courier towards the end of the video.

[@MattThomasLondon]

+sofiahoac Yeah, he's a nasty piece of work

[@sofiahoac]

+mattua Question for you - on your last slide (the only one that I found a bit confusing) and at the point where my computer picks a random number (you used 25) to send to the bank. Does my computer pick the random number once and use it for all future sessions with my bank or does it pick a new random number every time I log on to my bank?

[@MattThomasLondon]

+sofiahoac Good question - the pre master secret is chosen on the client computer each time a new session is established. So the same public/private key pair will be used each time since they belong to and are installed on the bank's webserver. This public/private pair are used to share the NEW symmetric session key between the client and server. In the analogy of the bank, housebound Humpty Dumpty and physical chests, this is as if Humpty buys a new symmetric box every week with a new key which he needs to copy and send the bank using the bank's same old asymmetric chest..... He might want to do this perhaps every month because even though the courier has never had a chance to get his own copy of the key, perhaps if he sees the same symmetric chest going back and forth, he can spent 30 mins trying to crack the lock - this would be the equivalent of cracking the AES symmetric encryption algorithm without the key.

[@femyraecheljoy9100]

one of the best videos on SSL, thank you very much...helped me understand how it works after going vainly through coupleo f other videos. very good

[@Vivek-jo9jl]

Can;t be explained better than this - Cheers Matt!

[@claudiutache5976]

Thank you ! Very explicit.

[@riccardoandreetta9520]

yes man !! this is absolutely NOT an easy topic, all about cryptography isn't. But your way of explaining things, is unbelievable. I sometimes needed to watch it twice, because the topic is not that easy, but this video is really wonderful. I will go on watching all the others too. Hope you really teach somewhere in a university to students ... we all had good teachers, normal teachers, unfortunately BAD teachers that couldn't explain anything to the students. You are an on-line AMAZING teacher.

[@MattThomasLondon]

Thank you so much for that feedback

[@arunmanoharan]

Excellent detailed video in simple terms. Fantastic work!

[@MattThomasLondon]

Thanks Arun, appreciate that

[@madfox5085]

no comments, u r extraordinary in explaining things. i finally ended up in this video after many videos where i was struggling to understand the concept. Thanks to humpydumpty

[@virajpadte]

I have seen a lot of SSL videos and I can tell you for sure that this video is awesome.

[@MattThomasLondon]

Thanks Viraj - really appreciate that

[@mbarnwal]

I second that.. This was very nice explanation.

[@thecosmologist]

Its wasn't boring or tedious it was brilliant, very clear and in one viewing i have grasped the concepts. Thank you so much for your time and effort in making this video. By the way do you have a bird?

[@webikehike]

Outstanding.

[@dvberlindvd]

An Excellent Video.

[@henrichsury98]

Great videos! Thank you for education

[@ashutoshningot4483]

Finally got more than I was looking for . @Matt Thomas God bless you :) Please give info if you have a website or blogging site or channel or tutorials or more. I will be excited to join your tutorials. Thanks One more #NoResonToDislike.

[@utki17]

you definitely fucking hammered this thing in my head once and for all :) !! YOU ROCK !! keep the great videos coming !

[@gaurav28ch]

Incredible explanation of a complex subject. Congrats !!

[@SuperBluesblues]

Great explanation . Thanks a lot!

[@MrVigneshhyd]

Amazing explanation. You made this complex subject easy. Thanks a lot for your awesome presentation.

[@MattThomasLondon]

Thanks Vikram..glad you liked it. If you find this kind of stuff interesting maybe check out my Bitcoin/Blockchain series ..similar concepts but perhaps more exciting application of them kzbin.info/www/bejne/rqikY4ehmKaEnbM

[@vivekacharya3110]

WOW super explained.. I watched many videos on this.. this is super well explained.... thank you so much... keep posting..

[@craighallett6590]

Excellent explanation!

[@edithmicheleb1]

The actual relationship between the public/private key pair is that when the box is locked with one, it can be unlocked by the other. Therefore the Bank is faced with the problem of getting the public key to Humpty in a secure way. How does the Bank accomplish this? It can't send the public key with an unlock box because the courier can make a copy and then be able to open the box the next time the Bank needs to send the box to Humpty - the courier has a copy of the public key and can open the chest just like humpty can.

[@andreaszetea-ster900]

Thanks for the explanation Matt. This was really useful and well explained.

[@marionthomas1257]

Thanks - good series...keep them coming

[@ahmadelbeltagui1034]

Very clever, Thank you.

[@kamilszewczyk6005]

Thank You, these are the best explanations I have ever seen

[@MattThomasLondon]

Thanks Kamil, appreciate it

[@saravanaga]

Excellent clear explanation. Very much useful. Thanks for your wonderful work.

[@MattThomasLondon]

Glad you liked it - I have a new video on public/private keys as part of blockchain/bitcoin series which shows you how to generate your own keys and play around with them and really helps to clarify the material. kzbin.info/www/bejne/i6TCgJppf8qLn6s

[@saravanaga]

Thanks Matt

[@mdziaurrahman3392]

Thank you for your effort very well explained

[@sonaltanpure]

Very nice tutorial. keep coming more..

[@ilariamartiradonna6223]

great work! I loved your video: it made clear things that others video didn´t

[@pedrocontrerasavendano8578]

amazing explanation, thanks!

[@vk148]

Excellent video on SSL...

[@bazilian0]

Great explanation of a complicated subject.

[@manishtyagi2816]

Exceptional, thanks Matt

[@litontonaton]

You are a great teacher!!! Would appreciate your lecture slides as well, if you can kindly upload them somewhere. So that i can stop taking crappy screenshots :-S

[@ziadfawzi]

Thank you so much.

[@chaturalive]

Very clear explanation. Thanks

[@ryanchacon5883]

I'd be interested in a http series

[@omarkhaled4302]

you're a master

[@PratikBandarkar07055]

awesome explanation in very simple terms.

[@MattThomasLondon]

Thanks Pratik

[@CarlosReyes-sb7sk]

Awesome explanation. Thank you.

[@mangooo1156]

Really detailed video! Thanks a lot!

[@sefton999]

Excellent tutorial. Thanks

[@swapnilkashid5220]

Thank You !! Really good explanation of concepts

[@RahulKumar-jz7nq]

Good One, I like it, Thank you!!

[@supamc]

Fantastic explanation. Like and subscription for sure!

[@dilrajsinghkhalsa]

Awesome explanation

[@willischan3969]

Very good explanation 👍🏻

[@kimpetermesenholler831]

Great explanation! Thanks!

[@uwemueller1918]

Perfect! Thanks a lot!

[@pchebbi]

QUESTION:- Hi Matt, have a quick question (you might have answered it in subsequent videos, though). In the slide - "Why do we need https/SSL/TLS", last line says - "bandit can read the data and potentially modify..". So, this leads to my question as follows: When bank sends the chest and PUBLIC key via this Evil Courier Service, bandit has access to this PUBLIC key, right? What if he modifies or corrupt this PUBLIC key and makes it un-usable? After all bandit guy can get into any sort of negative adventure, right?

[@MattThomasLondon]

if he makes it unusable, then Humpty Dumpty will never lock up the valuable things in the chest in the first place, but yeah he could do it just for fun :)

[@jimgee1000]

Hi Matt, Thanks for your efforts. They are steadily helping to clarify the concepts, for me. One point I wanted to make following on from Warrior's question: What if the bank sends the box with his public key to humpty and the evil courrier forges the public key and the certificate? I presume the certificate is the only means humpty has for verifying the public key is really the bank's. So it comes down to how he is assured the certificate has not been forged. If the answer is the web of trust (which I have heard about) - perhaps you cover this in later videos - then maybe mention it here... because I'm now not sure whether you have covered this in upcoming(for me) subsequent videos. Seems like a legitimate time to flag this because you didn't mention it. Just looking for confirmation... not trying to bad-mouth the video, which is very good. Thanks.

[@loudywen]

best!!!

[@kiranv5078]

So we use asym and sym both... But the humpty did not initiate anything here.... But originally the client need to initiate a connection first then server send the files... But here why bank asking the passport directly

[@kasun0087]

Awesome explanations keep going bro !!! :)

[@richardmcdonald2737]

This is perfect

[@MMABeijing]

19 mn into the video, i have questions that you might answer later on but I am still going to ask now: I guess the in your mathematical formula e stands for encryption, d for decryption, but what does n, p and q stands for ( I don't even see p and q on your slides). thank you

[@Akshay-cj3hq]

Hi Matt, why does the client send a random number rather than just straight up send the symmetric key?

[@lakshyam]

Really good explanation. Do you have the slides used?

[@dyadaval]

Matt, nice video. Is there ppt format to read offline or as quick refresher?? can you please share. thanks

[@athmikagowda6728]

Matt Thomas Hi Matt, I have one question , both server and client after receiving random number , both will use random number as a input for determistic function to generate the symmetric key , which is that determistic function ? is this explained in coming session? Is this determistic function is Diffie Hellman key exchange algorithm?

[@virajpadte]

Waiting for a detailed HTTPS video

[@zareefanam28]

Why is the session key a function of the symetric key, as opposed to the symetric key itself?

[@wangyeelinpamela]

This was really helpful :D Thanks!