3
votes
1answer
62 views

Convergent Encryption: integrity and authenticity

I have one question about convergent encryption. Suppose I use AES-256 in CBC mode. I need a 256 bits key and a 128 bits IV. If I use SHA-256 to hash one file, then I can use directly that hash as ...
3
votes
2answers
67 views

CBC-MAC key can be added to ciphertext?

I use AES both CBC and CBC-MAC to encrypt some stuff. I generate one key for CBC and one different key for CBC-MAC. Does the second key (for CBC-MAC) need to be secret? How to join such key with the ...
2
votes
1answer
286 views

Is CBC mode encryption vulnerable to a reordering attack?

I know that, if CBC-MAC is used in such a way that the tag is the concatenation of all the blocks' outputs (and not just the last one), it's insecure under CPA for the simplest case of 2 blocks ...
2
votes
1answer
242 views

CBC-MAC forging textbook question

I found this question about CBC-MAC forging and want to make sure I understand it: Let a and be be two strings of block length one. Suppose the sender sends (a, CBC-MAC(a)), (b, CBC-MAC(b)), (a||b, ...
2
votes
1answer
205 views

Question about CBC-MAC

I found this question from a textbook but I don't really understand what it is asking: Suppose $c$ is $1$ block long, $a$ and $b$ are strings that are a multiple of the block length, and ...
0
votes
2answers
228 views

What block cipher is used for CBC-MAC?

What block cipher is used for CBC-MAC? DES, AES, 3DES? Or it doesn't matter?
2
votes
2answers
374 views

Modifications of CBC-MAC

I'm preparing myself to exam, but I have a lot of troubles with rigorous proofs. This post is very long, but this is because I remind here 2 long definitions. At the beginning I want to remind the ...