really good teaching, I think it's hard to find explanations like this on the internet, and for free, thank you.
@machintruc40546 жыл бұрын
Even my own cryptography teacher doesn't give so much explanations
@introductiontocryptography42239 жыл бұрын
Please have a look at Lecture 16 and 17 of this series where I introduce elliptic curve cryptography. Good luck!
@youmah259 жыл бұрын
Danke
@zainabzainab-pi6my6 жыл бұрын
Introduction to Cryptography by Christof Paar Thanks sir.
@utsavprabhakar50725 жыл бұрын
danke professor. You have been amazing
@gauravtyagi84854 жыл бұрын
Thanks :)
@jonjett25843 жыл бұрын
Pro tip: you can watch series at Flixzone. I've been using it for watching a lot of movies these days.
@SpomenkoJabucar8 жыл бұрын
Top notch lecture. Clear, concise, extremely helpful and great fun. Professors of the world, please take a note.
@annablendermann6 жыл бұрын
Brilliant. I've been searching for good explanations of DES algorithm details and this is one of the best lectures I've seen. Guess I won't need my textbook anymore!
@akf2000 Жыл бұрын
I actually watch these for fun, it's not my specialist topic but I've spent 7.5hours so far and enjoying it!
@sahaneakanayaka3394 Жыл бұрын
Really appreciate this lecturer because this is the best explanation I have found on DES. Thank you for put it on youtube ❤🙏🙏
@elnurazhalieva12626 жыл бұрын
The first professor I've ever met, who allows sleeping in classes
@jeovanny1976andres3 жыл бұрын
Es mejor que duerman y no molesten a los demás. Nadie está obligado a aprender.
@David701545 жыл бұрын
Such a great professor. The way he teaches and breaks down this subject is just awesome. Thank you
@acid123ist4 жыл бұрын
Professor Paar, this is my second time going through this lecture series. I cannot express my gratitude towards you in any way it would simply fall short. This is the best crypto lecture series one can have. I wish I could visit one of your lectures in person someday. Take care.
@creativegiant1483 жыл бұрын
Hey I am also Indian Im just curious for what purpose were you learning cryptography Im doing it for fun.
@acid123ist3 жыл бұрын
@@creativegiant148 i had netsec crypto in my masters
@creativegiant1483 жыл бұрын
@@acid123ist oh nice, well im just a freshman who got super excited after watching The imitation Games and made it through the 5th video of these lectures.
@cikechukwujohn10 ай бұрын
And sleep in class. Forgive me, please.
@vikramadityamathur24204 жыл бұрын
Grossartig Lekteur. Ich liebe die bewegende Wandtafeln. Thank you for the lecture, great moving synchronized blackboards...
@Mindraker17 жыл бұрын
Confusion = substitution. Diffusion = transposition. This makes instant sense to classical cipher fans.
@vishalsyoutube8 жыл бұрын
I loved to see you teach with this kind of earnesty and a high level of dedication to cryptography and towards your students & viewers too. Wish we could have more teachers like you here in India.
@realGeezus5 жыл бұрын
@@mritunjaymusale True
@David-yh1yf9 жыл бұрын
29:24 ''If you do youtube on your laptop, it's like the biggest wasted 90 minutes of your life.'' Well, fuck
@RohitRaj-qm3no9 жыл бұрын
Sir , That was One of the Best lecture i have learn in youtube ... Thanks for it . you are doing a very nice job keep it up :) ....
@ArtyBoney7 жыл бұрын
Can't wait to continue my Master studies in Germany! Thank you Professor for these free and online lectures. I really value your enthusiasm and ability to distribute information to students.
@fahadtanwir85279 жыл бұрын
seriously, you explain far better than my teacher. I would recommend my friends to go through your lectures of crypto.... THANKS...
@Leo-fr6pl6 жыл бұрын
I was facing so much difficulty to understand this from textbook, but this man cleared all my confusions. Thank you very much Sir for your hard work and dedication.
@KaustubhGhanekar9 жыл бұрын
Tip: You can watch this video at 1.5x speed and still understand.
@ethereumtutorialsandapps9 жыл бұрын
+Kaustubh Ghanekar thank man. true!
@michelledawson63466 жыл бұрын
Agreed. I watch a lot of these between 1.5 and 2 and still understand. Then I wonder how people stay at such a slow, steady pace while lecturing...I wish my brain and speech speed worked like that. I feel like at 1.5, it's normal speed :/
@deusvult57386 жыл бұрын
Useful AND practical.
@aminopalastine22546 жыл бұрын
I do it too 😂 but when you turn to normal it's like he speek tooo slowly
@DanielNyong4 жыл бұрын
you must not be taking any notes
@Solomon50055 жыл бұрын
You are a good man because you shared this knowledge with the world, Thank you Sir.
@cherianzachariah5003 жыл бұрын
Wonderful lecture. Loved the way how the F-Function was broken down and explained. Thank you for the lectures and looking forward to your upcoming lectures.
@gurungbrijesh896 Жыл бұрын
i would give my 100% attention and focus every single second of his lecture class if i would be in that class
@creativegravedigger72892 жыл бұрын
00:00 DES Intro 24:19 Feistel Network 42:54 DES Internals
@BrendanChewy4 жыл бұрын
as someone learning both cryptography and german, this is such a helpful lecture :)
@alejandrorodriguez37714 жыл бұрын
31:38 the best part of the lesson, OMG what a good teacher !!!! "It´s perfect, because it´s wrong"
@cpandit8038 жыл бұрын
Awesome Lecture Christof, gave the trivia as well as the concept of DES. Thank you for uploading.
@Marcos-nl7el4 жыл бұрын
thank you for this material, the slides are really good and the way you explain this is so friendly.
@shahmuhammadnizamani95867 жыл бұрын
Thank you very much sir, you earned me my 10 marks of presentation :)
@VoteScientist5 жыл бұрын
Ok I've watched the lecture twice, now I'm going to read the chapter, then I'll code up the techniques so I really understand the material. I used this method for chapters 3 and 4. I'll be back for lecture 6 in about 2 weeks.
@solkid19956 жыл бұрын
Thank you very much for sharing. It means a lot for the those of us in the disadvantage part of the world.
@benegesserit98364 жыл бұрын
this is my food for thought for partial unemployment days, great lectures!
@madhusreebera44842 жыл бұрын
Thank you so much. Your explanation was beautiful and you made DES so simple and easy. Beautiful lecture
@nnnscorpionnn9 ай бұрын
I love the way he says "that's it for today thank you very much"
@slaozeren87424 жыл бұрын
I do not understand how someone can sleep during such a beautiful lecture?!
@dattran00008 жыл бұрын
you are really a master of Cryptography!!!!
@redisit10 жыл бұрын
Thnx from Albania. I liked the explanation and I'm so excited that I'm going to write my own DES code. :)
@sureshkumar-zw9zv4 жыл бұрын
Really hats off professor . I can understand easily and also i m watching continuously dis lectures makes very helpful to learn
@1216superkiller9 жыл бұрын
Thank you so much! Much better explanation of DES than my professor..
@mpill6 жыл бұрын
Thank you for uploading this,,,No one does the explanation better than you,,,,
@shreyashful8 жыл бұрын
THE LECTURE MADE MY CONCEPT CRYSTAL CLEAR.THANKS A LOT SIR.THAT UNIVERSITY WOULD BE LUCKY WHERE YOU ARE TEACHING.
@timhewson9867 жыл бұрын
I really enjoyed this. Very clear and well illustrated.
@jamesgoodman26417 жыл бұрын
Great lecture on encryptology! many,many thanks to prof Paar
@GaneshHarugerii10 жыл бұрын
I was attentive through out the video. thank you so much for the great explanation.
@vsk02084 жыл бұрын
Awesome explanations, you are awesome Sir. Thanks for sharing your knowledge with us with no cost.
@karthikhebbar986410 жыл бұрын
Really great explanation ! Helped me out a lot in understanding DES
@LokeshSharmaa7 жыл бұрын
Very helpful. Thanks for making it public.
@pkyrkos710 жыл бұрын
Very nice and interesting video! I wish we had professors like you in my university !
@fountainhead416110 жыл бұрын
Christof is a great lecturer.
@VoteScientist5 жыл бұрын
Well Yes! the SBoxes can be rearrange into a simple vector so that the 6-bit input directly address the appropriate SBox vector element.
@internetbird10 жыл бұрын
Thanks, Christof. Very well explanied.
@nicolagalloro10288 жыл бұрын
Great lectures, very clear explanation! Nice job! Thank you
@yosefdiriba182 Жыл бұрын
My english is not perfect but I would said to thanks to this teacher. THANKS
@helton.abrantes6 жыл бұрын
Pleasant class. Thank you, professor!
@aayushiagarwaal6 жыл бұрын
hello sir,i have a doubt.i understood the concept of f function.expansion box expand the 32 bit into 48 bit.some bit connected twice .so my question is why some bit is connected only twice .we just have to make 48 bit is there any thing any single bit connected thrice or four times.if not then why???? @christofpaar
@DonBhupi8 жыл бұрын
From what I've read: confusion refers to making the relationship between the key and ciphertext more obscure whereas diffusion is exactly what you've explained in the lecture. So, confusion is when a cryptanalyst can deduce multiple keys from a set of ciphertexts but can't tell which of the keys was used and diffusion is when a cryptanalyst can't deduce a definitive plaintext from a ciphertext because the statistical properties of the ciphertext have been flattened, i.e. diffused. In this lecture, you say that confusion means a simple substitution that makes relationship between the plaintext and ciphertext more obscure. Is it not a different or incorrect interpretation?
@johnvandenberg88838 жыл бұрын
Spot on. The lectures are great, but the explanation of confusion is rather confusing ;-)
@rahulait Жыл бұрын
These kind of lectures are difficult to find and especially how much hardwork professor has put in to teach unlike teachers and professors here who just tell the book name and chapters to study.
@asepsetiawan404 жыл бұрын
This is such an amazing course, but could you help me to add a subtitle for each lesson to people who hasnt a good skill in english
@febriputrasandhya55844 жыл бұрын
i believe i can fly
@fahmiramadhan71664 жыл бұрын
sooo before you go
@febriputrasandhya55844 жыл бұрын
@@fahmiramadhan7166 hey yoshii masi idup kamu
@HatemBouabana9 жыл бұрын
Great teacher ! very good explanations. Thank you very much.
@ji10465 жыл бұрын
That image is wrong in 47:50. bit 1 goes to 58 instead of 50 and bit 2 goes to 50 instead of 58. Same goes for IP^-1 bit 58 goes back to 2 and bit 50 goes back to 1 as you can also see from the table.
@johnyork8236 жыл бұрын
Wonderful lecture Dr. Paar! The part where they expand the plaintext from 32 bits to 48, and then go back to 32 bits in the S-boxes confuses me. How do they guarantee that they aren't losing data? It seems you could lose data if you didn't do this carefully--did I miss something? (Obviously they don't lose data, or DES would have been dropped years ago.)
@gravity46765 жыл бұрын
There are some football players known as genius. And know I guess I know who to call genius in teaching. :-) Thank you Mr. Paar.
@halildogan64352 ай бұрын
Thank you Professor, great lectures
@mr.shanegao3 жыл бұрын
DES intro 0:00 Feistel networks 24:30 DES internals 43:00
@BoultAudio9316 ай бұрын
@17:52 In definition of confusion, it should be relation between key and ciphertext obsured.
@LordMoopCow2 жыл бұрын
Just bought this guys book thanks for das buche!!!
@dARKf3n1Xx9 жыл бұрын
Thanks for the lecture, From India :)
@volkerschmidt51909 жыл бұрын
Great lectures !! I dropped acidentally and driven by private interest into the topic of cryptography. Cant stop myself learning more I think I get adicted !!! There is a verry good and knowledgable book by Simon Singh I read last night. Think there must be also a german version available. Driven by this I tried to understand the german ENIGMA machine and the history and methods of the breaking of its code. From there I wanted to know and understand more about actual math based cypher algorithms and got hooked by the history of RSA (the first unsymetrical algorithm). Cant still stop myself there seems to be unlimetet content at the net and even here on youtube. GIVE ME MORE...
@bananian7 жыл бұрын
Volker Schmidt Omg i came here from numberphile's video on the Enigma!
@nullentrophy3 жыл бұрын
@@bananian same here
@SamusRidley4 ай бұрын
I don't get the point of the s-box indexing using outer bits for rows and inner bits for columns. It is just a substitution table, where every input maps to a particular output. Therefore you could just reorder the values in the table to match the index order of the input. It provides no cryptographic benefit to order them in the way that they are. It just makes it *look* like it's a more sophisticated operation than it is.
@hariprasadyalla9 жыл бұрын
Very nice explanation sir. I really enjoyed your lecture.
@norah50733 жыл бұрын
Amazing. That is what should proffer looks like
@damejelyas3 жыл бұрын
I think there is a mistake at 1:20:27 8 is 0100 not 1000 but this is the greatest lecture about des
@dannyboy_666 жыл бұрын
very helpful, the teaching is great too good job.
@yash23635 жыл бұрын
This was amazing! wish we had teachers like you in india
@tchaivicon8 жыл бұрын
Lecture so brilliant and helpful, thanks a lot prof.
@DeckSeven10 жыл бұрын
I liked all of Christof Paar's lectures which I watched so far! Great stuff and thumbs UP! However, the entire series of lectures and semester was recorded and took place in 2010-2011. This was before Edward Snowden's revelations in 2013 about NSA's global espionage, so the Professor may have not known the full story and told his students only what he has been told at that time, on why the NSA and their contractor IBM have not told anyone about the DES attack vulnerability (S-Box configuration). But cypherpunks and german crypto developers like me have a different opinion or theory today... It is more likely that NSA wanted to build in a backdoor in DES on purpose in the first place, in order to be able to break in and spy on any company, bank or targeted individual who used the popular DES cipher algorithm over the last 20-30 years. Just take a look at "Heartbleed bug" vulnerability in SSL online encryption which was revealed this year! The NSA knew about it, didn't tell anyone and exploited it for years! This may all sound like a conspiracy theory, but seriously, today everyone knows that the U.S. government and NSA do all these surveillance and espionage operations on the internet, especially against us Germans, even if they deny it. Edward Snowden revealed it himself, so nobody will argue about it today. It's not a conspiracy theory any longer but a conspiracy fact. But alright, let's assume the story was like the Professor said, that the NSA kept the vulnerability secret in order to be safe from attacks, which I find a bit sloppy for a "National Security Agency" with a budget of billions of dollars! You think the NSA would be so stupid and let IBM develop a half-secure cipher for themselves?? No no, that sounds like plausible deniality to me. I don't believe it. I think normal cryptographers have not been told the true reason why NSA kept the vulnerability secret. That's my personal opinion. You can't trust the NSA on this. They tell you one thing, but there may be more to the story as people think. Global industrial espionage has always been a big thing for any government or big corporation. There are many cipher algorithms today on the internet which people can download and use, but which have secret backdoors embedded for the government or spy corporations to break in silently and read all your encrypted messages easily. So be careful! These things don't happen, because NSA made a mistake. Don't be too naive to believe such a thing! NSA does not make mistakes. They want to spy on everyone on the global internet and they know what they're doing. It is more likely that DES was a clever spy scheme or fraud by the NSA. A malicious Cipher algorithm designed on purpose by NSA! But I don't want to insult the DES developers or anyone who loves DES. All I'm saying is I don't believe the story about the secrecy of the DES attack vulnerability.
@paul.g.wolfson7 жыл бұрын
You make the statement around time mark 52:30 that bit level permutations are fast in hardware. This is counter-intuitive because crossing lots of wires on essentially a 2-D chip seems difficult to implement. Either you would need recursion or a fair amount of real estate on the chip itself.
@introductiontocryptography42237 жыл бұрын
To my knowledge, the bit permutations can be achieved in standard ICs quite easily using standard metal routing. regards, christof
@divamlehri98507 жыл бұрын
Sir at 15:00 you explain about Shanon's confusion property where you have explained that it establishes relation between plain text & cipher text but according to this property the relation is between the key and cipher text not between plain and cipher text ! Can you please upload a video on RC4 Algorithm?
@VoteScientist5 жыл бұрын
I wonder if the S-Boxes can be rearranged so that the lookup can be direct, without all that bit0-bit5 and bit4-bot3-bit2-bit1 nonsense.
@peacetokyo7 жыл бұрын
If the sixteen 48-bit round keys scheduled for successive rounds in the encryption process for DES are replaced by successive 48-bit blocks of the 768-bit key, What would be the weak keys for this variant of DES ?
@ravivarmavikneswaren35537 жыл бұрын
You're an amazing lecturer!
@bstemic36233 жыл бұрын
Superb lecture. Thank you
@faizanshahansari11935 жыл бұрын
The output is wrongly mapped in the ppt at 54:15
@evramhany63689 жыл бұрын
please DR ..... how does DES deal with extra bytes where these bytes couldn't construct a block ??
@introductiontocryptography42239 жыл бұрын
+Evram Hany It depends on your application. Often, you can just fill them with dummy bits, e.g., all zeros. The receiver has to decrypt everything received and can discard the dummy bits after decryption. In many real-world protocols you have to send in the beginning header information about the total length of bits or bytes that you are encrypting and sending. This way, the receiver will know which of the received bits are dummy bits. I hope this helps. regards, christof
@WhateverOwO4 жыл бұрын
may I ask, what's is the algorithm that makes the subkeys for every round and where do I find the S-BOXS 2 to 8?
@thelasttimeitookashowerwas70696 жыл бұрын
i was on twice the normal speed until 27:50 into the lecture but then i had to make it to normal coz i felt like i heard a never-heard language. I could still not understand him in the normal speed though. oh must be german, why did he change the language lol
@amitrawat26385 жыл бұрын
to explain something. he says, I switch to german for a bit
@Leandro-xx7bs8 жыл бұрын
Very good lesson!
@tabasumsami69105 жыл бұрын
Best explanation ...!!!
@MaximeDendauw2 жыл бұрын
I love this professors’ classes. I’m stuck on the 6 bit to 4 transformation with the s boxes tough in the sense that you lose information. If it sometimes maps to the same 4 bit number, how can you inverse the operation to decrypt. I mean e.g. 08 could point to multiple 6 bit patterns….
@introductiontocryptography42232 жыл бұрын
Good observation. You are right, one cannot inverse the S-Box because of the 6bit-to-4bit mapping. HOWEVER, due to the way a Feistel network operates, one does not have to inverse the S-Box for decrypting. Rather, for decrypting the receiver merely needs to re-compute the same S-Box, again in the "forward" direction. Please have a look at the blackboard drawing starting at 36:26 where I (try to) explain this fact.
@jaeekshirsagar219510 жыл бұрын
Can we use 3DES in EED mode with K1,K1,K2 keys? how will the strength differ in finding the keys in terms of EDE and EED mode?
@mintesnotbezabhi64093 жыл бұрын
at the start of the lecture the major operation we do to cipher the text are confusion & diffusion, which confusion only is not enough. But later in the lecture, the permutation is has no significance on the ciphering the text. can anyone clarify?
@introductiontocryptography42233 жыл бұрын
Good question. The permutations IP and IP^-1 (very beginning, very end) of DES do not contribute to the security because they are publicly known and every attacker can *undo* the IP and IP-1 permutation if the attacker knows the plain- and ciphertext. This is different for the permutation P within the f-Functions. Since the attacker does NOT know the internal values before and after the permuations, they cannot be reversed by him/her.
@ambreenilyasathar44806 жыл бұрын
Why the initial permutation is performed when it gets reversed at the end??
@cwildsblog8 жыл бұрын
Super Anekdote am Ende :D
@rastovicfilip7 жыл бұрын
Thanks for an awesome lecture !
@BlackProductionInc9 жыл бұрын
These lectures are amazing, thank you for making this understandable in a pleasurable way :) If I am to learn this from my local professor I'd probably jump off the building, my face melted from infectious autism.
@lejlasini91109 жыл бұрын
Hi, nice series of lecture! (and book of course!) Do you eventually plan to make another more advanced book like "Understanding cryptography 2" or sth like that? When yes, when is the release planned? When not, could you possible mention some another cryptography literature, which (more or less) continue in your book? Thank you!
@introductiontocryptography42239 жыл бұрын
+Lejla Sini Yes, I just released the lecture notes for my more advanced course "Implementation of Cryptographic Schemes". This is a 3rd year bachelor course in our IT security program. The prerequisites are my Intro Crypto I & II courses (= those 24 lectures that are here on KZbin). It is helpful to have some basic experience with programming in order to understand pseudo code etc. I do NOT have videos for this but the lecture notes are freely available: emsec.rub.de/teaching/literature/ The notes do not have the same level of quality as our book Understanding Cryptography, but I believe they are still useful for self-study. Note that the material covers more advanced topic which are typically not found in textbooks. cheers, christof
@Palash210419947 жыл бұрын
Hi Mr Paar , Great lecture. One thing i would like to ask ?S block(s) which are used in DES are still statically there present in the algorithm or they are generated in runtime? If we change the S blocks does that violate DES ? Are they tightly coupled to the permutation box ? or are they mystical ?
@introductiontocryptography42237 жыл бұрын
The S-Boxes are static look-up tables. They are fundamental for the security of DES and, yes, they interact with the P permutation. For a deeper understanding of the S-Boxes, one has to study differential cryptanalysis, a powerful attack against which the S-Boxes provide protection.
@34521ful6 жыл бұрын
Hi Professor, quick question, in the "high level diagram" you had "" confusion box->diffusion box(Confusion box first, THEN the diffusion box) , but when we got into more detail, we have expansion (diffusion) happening BEFORE substitution (confusion), why is this? Thanks in advance!
@introductiontocryptography42236 жыл бұрын
The order of diffusion-confusion does not really matter because there are 16 rounds, i.e., there is a constant sequence of diffusion-confusion-diffusion-confusion- ...
@mamtarani47726 жыл бұрын
thank you sir for these great lecture.
@yurilsaps5 жыл бұрын
Thanks so much, I loved it!
@smrititiwari82436 жыл бұрын
wow, explained s box really well !! :)
@VoteScientist5 жыл бұрын
The IP table can be computed by Table[ixRow][ixCol] = ((ixRow * 2) - 0) + ((8 * ixCol) + 1) Rows 0-7 Table[ixRow][ixCol] = ((ixRow * 2) - 4) + ((8 * ixCol) - 4); Rows 8-10 Everything 0 based