For someone who doesn't make videos consistently, this was wonderfully put together mate. Very clear explanation with helpful visual aids. Honestly I expected you to have a whole series on your channel! Haha
this is only my second time commenting on youtube after using it for years, "you are super awesome" i am so struggling in the very expensive master degree which only have teachers teaching in un-understandable language. This should be the way they taught in every university speaking human language and showing human diagram like this.
This is fan-bleedin-tastic. I was looking at my course notes and I was super confused. Now that I see it in practice it's pretty simple. Lotsa repetition in DES.
Very useful guide! Had to do a full DES encryption by hand in less than a day, which took me like 6 hours or so, making mistakes on the permutaions and initially using the wrong tables (IP with PC-1 tables as they are similar), but eventually managed. Thanks!
7:31 That's okay! I just need to know how to do one round of encryption for my information security homework Honestly I've not had a very good few days due to lack of sleep and the fact that no other source has straightforwardly explained how to do this :( There was also some other miscellaneous stuff... Plus I had an unfortunate mishap with food delivery today (I'm studying abroad in South Korea and the card reader the delivery man had was broken so I had to pay through customer service... Turned out I needed an alien registration card or an activated Korean credit card to pay, neither of which I had yet. that took over an hour to try and figure out, and in the end I just asked a Korean friend to pay for me! (She's awesome btw). But that was emotionally exhausting) Anyway literally thank God and thank you that you made this because I think I can follow along with this to do my homework I'm super behind on sleep and I need to get up for my information security class tomorrow. It will be 3 hours long! We're not even supposed to have classes tomorrow because it's a holiday, but the professor canceled class both days last week so he's using tomorrow as a make-up day! I was nervous that I might be up super late trying to figure this out. The homework isn't due tomorrow but we're doing example problems in class and stuff and I just want to understand as much as possible before I go, especially since his will be the last time I see my professor before the homework really is due Sorry that was long. I just needed to vent because I've been feeling really done, and I'm just so glad this was a good video. I needed that break
Pretty sure I don't need to know this, and will have to watch this video numerous times to get my slow brain around it. That being said, an impressive video, really enjoyed the watch. I'm learning about encryption in college atm. Thanks!
thank you so much I had a assignment on this and the excel sheet helped me trouble shoot my program with out your video I would have handed in a half working program
Hi just to add you forgot to mention the trimming of the KEY from 64 bit to 56 bit (@1:43 ), Although its writtend in your presention; just happens I missed that part myself. but overall REALLY HELPFUL! Thank you! :)
I'm a little confused, at around the 1:55 mark you had a 64-bit array, but after splitting it in half I see 2 28-bit arrays. Where did the other 8 bits go?
I don't see the use of permutating the key or the string. The permutation has to be the same every time, right? Otherwise, how would you know what order to do it in. But if it's the same every time, what is the point? Isn't it trivial to undo that part?
It's stated in the DES standard. If you go to the Wikipedia page on DES and scroll down to External Links you'll actually find a link to the DES standard PDF which contains the permutation orders.
Because all 16 subkeys are made by 56bit key. Not from 64 or 48. When u create 48bit subkey u use the same 56bit all the time but u create different 16x48bit subkeys.
DES is a block cipher operating on 64 bits simultaneously. The key consists of eight groups of 8 bits. One bit in each of these groups is a parity check bit that makes the overall parity in each block odd. So, although the keysize appears to be 64, the effective keysize is 56 bits.
They had to make it so the U.S could just about brute force it if needed in the 70's. Hence, the 56 bit key (8 bits dropped - odd parity). 72 quadrillion is a hell of a lot less than 18 quintillion. They originally wanted to neuter it to 48 bit strength, but a compromise to make it 56 bit strength was made.
I'm all for being proven wrong at times (that's how we learn) but if it was just a shift, what would take place in the first bit? Always 0? Always 1? It can't be blank... but then what do you do with the last bit? Throw it away? If any of those are to be true, it violates the Quantum No-hiding Theorem where information cannot be created or destroyed:)
@@ineapple I read a littl of Art of Assembly book once, and there was two operations The shift to the left always put a 0 as the least significative bit, while a rotation do what you did.
I would never have thought about it, that one day Johnny Sinns is telling me how encryption does work.
You obviously forgot that Johnny Sinns is not just a successful doctor but also a very successful programmer and data encryption specialist.
For someone who doesn't make videos consistently, this was wonderfully put together mate. Very clear explanation with helpful visual aids. Honestly I expected you to have a whole series on your channel! Haha
A Computer Science student here. This video is a great help, as we were tasked with making programs that implement the DES cipher.
This was an amazingly clear explanation of how DES/Block ciphers work. Thank you!
Nicely explained, step by step, with useful additional info. Also props for uploading the excel file with the functions. Great video.
this is only my second time commenting on youtube after using it for years,
"you are super awesome"
i am so struggling in the very expensive master degree which only have teachers teaching in un-understandable language.
This should be the way they taught in every university speaking human language and showing human diagram like this.
Very well structured.It saved my whole bunch of time and you explain better than the college professors so thank you IEOFIT
Kudos for putting it all into a spreadsheet. It helps illustrate what DES does in the background.
This is fan-bleedin-tastic.
I was looking at my course notes and I was super confused.
Now that I see it in practice it's pretty simple.
Lotsa repetition in DES.
OH MY GOD!!!! this just made so much sense and really simplified my cryptography class. My lecturer made it impossible to understand. thank you
You could say he… encrypted his message 🤣😅
I’m here for the same reason…
Very useful guide! Had to do a full DES encryption by hand in less than a day, which took me like 6 hours or so, making mistakes on the permutaions and initially using the wrong tables (IP with PC-1 tables as they are similar), but eventually managed. Thanks!
I am really stuck on the permutation. Can you give tell me how to go about it? This explanation is fantastic.
This was really impressive! I'm new to the field and enjoyed this. Definitely flexin with the Excel Spreadsheet though lol
Thank you. This is very helpful. Planning on stepping through this a few times.
The best and the most clear one!!
This was really insightful and very well made/taught. Thank you
7:31 That's okay! I just need to know how to do one round of encryption for my information security homework
Honestly I've not had a very good few days due to lack of sleep and the fact that no other source has straightforwardly explained how to do this :( There was also some other miscellaneous stuff... Plus I had an unfortunate mishap with food delivery today (I'm studying abroad in South Korea and the card reader the delivery man had was broken so I had to pay through customer service... Turned out I needed an alien registration card or an activated Korean credit card to pay, neither of which I had yet. that took over an hour to try and figure out, and in the end I just asked a Korean friend to pay for me! (She's awesome btw). But that was emotionally exhausting)
Anyway literally thank God and thank you that you made this because I think I can follow along with this to do my homework
I'm super behind on sleep and I need to get up for my information security class tomorrow. It will be 3 hours long! We're not even supposed to have classes tomorrow because it's a holiday, but the professor canceled class both days last week so he's using tomorrow as a make-up day! I was nervous that I might be up super late trying to figure this out. The homework isn't due tomorrow but we're doing example problems in class and stuff and I just want to understand as much as possible before I go, especially since his will be the last time I see my professor before the homework really is due
Sorry that was long. I just needed to vent because I've been feeling really done, and I'm just so glad this was a good video. I needed that break
:) I hope your days are better now
@@Appel070 They are! Thank you!
But I have midterms this week so I'm back reviewing
Thank you for your reply :)
@@whatsup968 I'm now invested in this LOL. How did the midterm go?
Great job! I was confused for two days and could not figure this out with our useful university materials!!!
Fantastically well explained, well done to you
Pretty sure I don't need to know this, and will have to watch this video numerous times to get my slow brain around it. That being said, an impressive video, really enjoyed the watch. I'm learning about encryption in college atm. Thanks!
This is an awesome video!
Thank you, and well done!
Thanks a lot you're the 3rd video I watched and yours was the best
thank you so much I had a assignment on this and the excel sheet helped me trouble shoot my program with out your video I would have handed in a half working program
This is crystal clear. Thanks a lot!!
Thank you! This was a perfect explanation!
Good job sir! Thank you for sharing your work!
Omg thanks, this was exactly what I was looking for :)
nice :)
you have put good effort into this , thanks!
I really love your Excel, Great job and thanks alot
Thank you!
That excel sheet would be very helpful!
Thank you man you and the excel that you made saved the day!
This video is amazing! Thank you!
Thank you so much for this indepth explanation. It really helped me.
Amazing explanation ! Thanks!
Great job! it's really helpful
superb brother.... good thanks for teach me... best .. good job keep it up for me...and you also.........
very clear, thank you!!
Enjoyed this video. Thank you !
Top quality content!
Brilliant video thanks!
Awesome video.
Thank you so much
Thanks!!! It's very useful.
thanks, you've helped me a lot with a college work
What an endearing person.
really very helpful for beginner, thanks :)
Didn't know the alt key trick. Very nice.
Thank you for the explanation and excel file
thank you very much tim!! have a good day
:)
very nice explanation
thanks a lot this helped alot♥
Legend!
great one!
Hi just to add you forgot to mention the trimming of the KEY from 64 bit to 56 bit (@1:43 ), Although its writtend in your presention; just happens I missed that part myself. but overall REALLY HELPFUL! Thank you! :)
Thanks for explaining :-)
thank you for this video
tşkler ediz hocam
Thank You !
explained it better then my lecturer, he took an hour
Thanks a lot.
good job man
Lol, vid's great, but the spreadsheet is a work of art. Thanks!
genius
Thanks
Neat.
Love that you walked through an example of this. Are slides posted somewhere ?
Hi Thank you
This is way better than that Udacity bullshit video
Good explanation. Thanks very much
I think there were mistake in rearranging key by permutation order (64 to 56 bit) - 1:55 sec
that's correct. You're the second person that noticed it. I used a slide from different permutated order. Good job.
what will i do if the plain text is not enough 64 bit?? example: I want to encrypt 7 chars ascii -> plain text = 56 bit binary input
I'm a little confused, at around the 1:55 mark you had a 64-bit array, but after splitting it in half I see 2 28-bit arrays. Where did the other 8 bits go?
I don't see the use of permutating the key or the string.
The permutation has to be the same every time, right? Otherwise, how would you know what order to do it in. But if it's the same every time, what is the point? Isn't it trivial to undo that part?
How to we choose the value for the key ? Can it be any value as long as it is 64 bits ?
Yes
Thanks IEOFIT
Is the permutation order random?
can you upload the power point file please
Do you have a re-upload for the .xlsx file?
how come the key at 1:55 your 49 bit for the permutated part is 1, shouldnt be 0 ?
its ok sir ! i just wanted to make a double in case iam missing something ! but your explanation is spectacular .
I had the same question....
Hi, text file this training video. thank you
Where does the permutation order come from???
+Ryan Allen it's part of the DES standard. If you pay attention to it, it has a pattern.
It's stated in the DES standard.
If you go to the Wikipedia page on DES and scroll down to External Links you'll actually find a link to the DES standard PDF which contains the permutation orders.
What have i learned today? Chopping things is fun
Please give a link to the excel file. The link in the vid is invalid.
It's in the description.
@@ineapple Thank you for the response. I have a request; please keep this channel active.
I'm a bit confused about where did the permutation orders come from.
From the DES standard. Seemed like a good order to mix things up.
@@ineapple Thank you so much for the explanation!
1:50 could have done with some explanation I feel.
The reason for the first and last permutations
crypto.stackexchange.com/questions/3/what-are-the-benefits-of-the-two-permutation-tables-in-des#6
Isn’t ASCII character 7 bits? In your example in 0:54 your Binary has 8 digits
How to decrypt? - Use the same algorithm, but reverse the order of subkeys
But why its called DES uses 56 bit key?
Because all 16 subkeys are made by 56bit key. Not from 64 or 48. When u create 48bit subkey u use the same 56bit all the time but u create different 16x48bit subkeys.
DES is a block cipher operating on 64 bits simultaneously.
The key consists of eight groups of 8 bits. One bit in each of these groups is a parity check bit that
makes the overall parity in each block odd. So, although the keysize appears to be 64, the effective
keysize is 56 bits.
They had to make it so the U.S could just about brute force it if needed in the 70's. Hence, the 56 bit key (8 bits dropped - odd parity). 72 quadrillion is a hell of a lot less than 18 quintillion.
They originally wanted to neuter it to 48 bit strength, but a compromise to make it 56 bit strength was made.
Isn't that shift operation wrong? I thought shifting was just moving all the bits to the left, and not rotating like shown in the video.
I'm all for being proven wrong at times (that's how we learn) but if it was just a shift, what would take place in the first bit? Always 0? Always 1? It can't be blank... but then what do you do with the last bit? Throw it away? If any of those are to be true, it violates the Quantum No-hiding Theorem where information cannot be created or destroyed:)
@@ineapple I read a littl of Art of Assembly book once, and there was two operations The shift to the left always put a 0 as the least significative bit, while a rotation do what you did.
@@rodrigoappendino You are absolutely right! 212 points for you Sir!
I have no idea how you do padding, so this was not helpful for me.
Amazing explanation ! Thanks!