
14:46
Yeah we can hear you

14:47
I can hear you

14:54
Yep

14:55
all good

14:55
I can see the slides as well

28:50
Nonce is the same for both encrypthing and decrypting right?

29:24
Yeah

29:30
Thx

30:05
Why is the nonce necessary if the cipher is not reversible without the secret key?

30:51
In case someone intercepts the message and tries to figure out the key themself

31:05
This way the key is slightly different each time in case it is no longer secure

31:26
The nonce introduces randomness into the message, so that if you send the same message, you still get a different ciphertext

33:14
xor again to decrypt

33:16
We can decrypt it by XORing it with the key

39:37
could you make this multi-use by adding a nonce to the key?

40:47
you could xor them?

42:21
If you were encrypting something that does have entropy like say a bank account number, would this attack still work if you had enough ciphertexts?

50:17
Is this the same problem as using a one-time pad multiple times?

50:58
c1 = c2

50:59
They would also be the same

54:51
a nonce?

55:37
What's the range of IVs given a 128-bit key?

01:01:13
If anyone can compute a tag then anyone can mimic that tag

01:01:18
Then you can modify the message and insert the hash for the modified message

01:01:37
to clarify, bob and alice has two keys one for the message and one for the tag?

01:03:59
Is S for secret?

01:08:35
Define authenticity

01:08:36
So for that to work you would encrypt the payload and then compute the mac on the concatenation of the packet headers and the encrypted part of the payload?

01:11:54
how is the shared key initially shared securely?

01:13:56
Alice encrypts the shared key with bobs public key

01:33:57
Thank you!

01:34:04
Thank you!

01:34:04
thank you!

01:34:05
Interesting lecture. Thank you!

01:34:10
Thanks so much!