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Cryptography: Crash Course Computer Science #33

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Today we’re going to talk about how to keep information secret, and this isn’t a new goal. From as early as Julius Caesar’s Caesar cipher to Mary, Queen of Scots, encrypted messages to kill Queen Elizabeth in 1587, theres has long been a need to encrypt and decrypt private correspondence. This proved especially critical during World War II as Allan Turing and his team at Bletchley Park attempted to decrypt messages from Nazi Enigma machines, and this need has only grown as more and more information sensitive tasks are completed on our computers. So today, we’re going to walk you through some common encryption techniques such as the Advanced Encryption Standard (AES), Diffie-Hellman Key Exchange, and RSA which are employed to keep your information safe, private, and secure.

Note: In October of 2017, researchers released a viable hack against WPA2, known as KRACK Attack, which uses AES to ensure secure communication between computers and network routers. The problem isn’t with AES, which is provably secure, but with the communication protocol between router and computer. In order to set up secure communication, the computer and router have to agree through what’s called a “handshake”. If this handshake is interrupted in just the right way, an attacker can cause the handshake to fault to an insecure state and reveal critical information which makes the connection insecure. As is often the case with these situations, the problem is with an implementation, not the secure algorithm itself. Our friends over at Computerphile have a great video on the topic:

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Source: https://blogema.org
Read more all post Computer Technology : https://blogema.org/computer/
38 Comments
  1. CrashCourse says

    Hey guys, there’s been a ton of news the past week about a vulnerability in the WPA2 protocol that protects our Wi-Fi networks, and since we say that AES is secure in this video, we thought it would be helpful to explain how it all relates. In October of 2017, researchers released a viable hack against WPA2, known as KRACK Attack, which uses AES to ensure secure communication between computers and network routers. The problem isn't with AES, which is provably secure, but with the communication protocol between router and computer. In order to set up secure communication, the computer and router have to agree through what's called a "handshake". If this handshake is interrupted in just the right way, an attacker can cause the handshake to fault to an insecure state and reveal critical information which makes the connection insecure. As is often the case with these situations, the problem is with an implementation, not the secure algorithm itself. Our friends over at Computerphile have a great video on the topic: https://www.youtube.com/watch?v=mYtvjijATa4

  2. memes and memes says

    .- .– . … — — .

  3. watch it says

    "For a 128-bit keys, you'd need trillions of years to try every combination, even if you used every single computer on the planet today. So you better get started" XD

  4. Shit DotNet says

    You provide great information, high-quality videos, and awesome graphics team. you should’ve brought a better tutor!

  5. Roger Vasquez says

    ….what

  6. Tim Etimiri says

    Thank you.

  7. Samuel Isaac says

    I loved cryptography as a kid so much that I actually used to entertain myself with frequency analysis. I had a lot of books on cryptography, and I used to try to crack the examples before the book explained them, the way people try to solve mystery books before they reach the end. Now I'm falling in love with cryptography again, but with a more modern, computerized version. Thanks Crash Course!

  8. HopeON Gaming says

    Anyone notice the minecraft creeper in the background?

  9. Viddesh K says

    Fantastic

  10. Tobias Peck says

    My Bro is amazing ate this and I can’t just get my head around it

  11. BENSALEM MOHAMED ABDERRAHMANE says

    thank numbertheory

  12. ramil hugo says

    search this cryptography research language

  13. Fabio Marsiaj says

    I just love the way you explain everything!! Amazing course.

  14. Maessy Chan says

    How many "key" have been said in this whole video?

    I love money but I hate number.
    Oh, money and number are two different things (no body ask) ?

  15. Victoria Fernandez says

    Hi

  16. Rowan Brown says

    “Adding another level of… complexity.”
    “He have been tricked, backstabbed, and quite possibly bamboozled.

  17. Vikas Kadel says

    Alan Turing blinking on the bug of engima was hilarious

  18. Sam Islam says

    Thank you for this leacture, but please try in the next time to talk slower, so the non-English speakers can understand you better.

  19. Blue Flash says

    Wow, this was actually the exact right speed to follow, awesome graphics and amazing good comparisons. I'm actually a little happier now!

  20. shalev ku says

    First time I had to slow down the video to 0.75 to get something from speedy here..but other than that good video!

  21. Lizzi Beetle says

    Maybe it would be good for YT to have a codebook. At least I would spend less time on the internet… And more time studying!

  22. Steven Hernandez says

    Why is she so gorgeous?.

  23. Mason says

    I like how Hank is the bad guy here ?

  24. demondojr says

    Your accent is cryptographically complex

  25. Alwyn C says

    That's by far the best explanation of asymmetric encryption (in particular, Diffie–Hellman key exchange) I've come across.

  26. Your Perspective says

    it was already complex topic and then you gave it to a woman to present that, God bless i could not get it at all.

  27. Bruce Lee says

    0:14 "There will always be bugs" and shows jquery LOL

  28. arvinder singh says

    Speak a lil bit slowly, This video is futile if information isn't conveyed.

  29. letylek says

    4 minutes in and my head already hurts, this ain't for me

  30. ansh sachdeva says

    hey carrie (or anyone else if you would like to help) , I wanted to understand that private key sharing( at 10:00) , so i thought of making myself a simple practical example out of it, but my calculations say your equation from 10:00 is not correct . can you please have a look?

    So If i have to transmit character '"P' (ascii 80 )from Boy A to B:

    >> I assumed x=2 would be private key of A and y=3 would be private key of B)
    >> I assumed my public key function as cipher(x,y)= (3^x % 7)^y
    Thus:
    – A would first Transfer cipher_a = 3^2%7 = 2 to B

    – B would first Transfer cipher_ a= 3^3%7 = 6 to A

    >> I assumed my publically available encryptor function as encrypted_text = cipher(B) ^x
    + ascii(character)
    – Thus, A would transfer the encrypted character 'P' to be as e_t = (6)^2+80 = 106

    >> I assumed my publically available decryptor function as ascii(character) = encrypted_text – cipher(A) ^y

    – Thus, B would recieve the value as val = 106- (2)^3 = 97 , which is not equal to our original value of 80

    Thus (B^y mod M)^x != (B^x mod M)^y != (B^xy mod M)

    But rather
    (B^yx mod M^x) == (B^xy mod M^y) but != B^xy %M

    Is this right?

  31. THEO says

    Why is Hank the bad guy?!!

  32. Dennis Asamoah says

    should be ((B^xy)modM)modM not ((B^xy)modM)

  33. Atticus Deutsch says

    4:33 LETS GET IT CARIE ANNE IS A GD shout out to the folks rip JOJO

  34. markmeson says

    I think you meant (B^y mod M)^x mod M = B^yx mod M … NOT (B^y mod M)^x = B^yx mod M

  35. zxx5 says

    here thinking how can I relate all that she said with bitcoin

  36. Rob Mai says

    Thanks cryptography!

  37. Jeremy Bailey says

    Hot oil in the medieval ages wasn't used like you see it in Hollywood.

    Oil was an expensive resources so what they would actually do is pour boiling water or extremely hot sand. Yes there was some occasions where it happened but that's an exception not the norm as it's portrayed.

  38. Collins Milgo says

    The amount of times hank has been attacked lmao

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