# All Questions

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### calculating the branch number/ active bundles of a cipher

I have read the papers Wide Trail Strategy and Wide Trail Design Strategy for Binary MixColumns. These papers describe the need for a good linear transformation in a cipher, a provable mechanism to ...
48 views

### Diffie-Hellman Key Exchange

I apologize if this is in the wrong section. I am completely new to Cryptography. I was presented with the following problem and I am trying to find something that will explain to me how to proceed. ...
31 views

### How to determine if ElGamal message was a quadratic residue?

Consider the following ElGamal encryption (using a generator of $\mathbb Z^*_p$): Key gen: find a big prime $p$ and $g$ a generator of $\mathbb Z^*_p$. choose $a\in \mathbb Z_{p-1}$ randomly and ...
144 views

### Stream cipher and block cipher usage in network data encryption

Stream ciphers are usually used for streaming data encryption, such as voice, and also for low layers data encryption. For example, MACSec uses AES-GCM encryption. In L3 ad L4 security protocols (...
77 views

### Questions about using PRF to construct PRG

Let F be a secure pseudorandom function with 128-bit key and 256-bit block length. Which are the following functions G are secure pseudorandom generators? (Select all that apply.) A. $G(x)=F_x(0...0)$...
23 views

### PKCS#7 Signed Data contains always different signature

I am wondering why CMS (PKCS#7) Signed Data contains always a different signature of the original data when the SHA256withRSA signature algorithm is used. (using ...