# All Questions

1k views

### What are the advantages of CBC over ECB?

From this question I understand that, for a block cipher, using CBC is better than ECB. It seems that if one only has part of the cipher text, then decryption is difficult because the decryption ...
257 views

### Unforgeability and type of adversary

When trying to prove security of asymmetric signature, for instance for existential (or strong) unforgeability against chosen messages attack, do we need to consider the signer as a possible ...
310 views

### Why use a timestamp and how can someone know it's the correct one?

Let's say A wants to send a message, so everyone who gets the message, can be assured that it's from A. A then sends a message ...
255 views

### Can anyone give an example where (asymmetric) crypto can go wrong due to selection of wrong groups?

Basically the title says it all. It would be great if someone could tell give an example using provable security. More information about groups can be found at: ...
526 views

### Why $n=pq$ with $p=2p'+1$ and $q=2q'+1$ instead of just $n=p'q'$ for RSA crypto?

For RSA cryptography, we know that the modulo $n$ is a product of two big prime numbers(say $p$ and $q$). However, in some documents I see an extension of $p=2p'+1$ and $q=2q'+1$ with $q'$ and $p'$ ...
177 views