# All Questions

56 views

### Looking for alternative key stretching

I am by no means a security expert, but I am curious whether functions that don't produce different outputs when raised to the power of N (without any psuedo-randomness) exist, that are as strong as ...
100 views

### Attack on BB84 algorithm for quantum key exchange?

I have a question which is related to the BB84 cryptosystem. We are not able to send single photons so instead we send $K$ photons at a time all with the same polarization. An enemy can separate one ...
140 views

### Is SHA-256 safe when used in this way?

I am wondering whether an attacker can gain any useful information from having several hashes of an unknown plaintext that differs in relatively few bits. For example, if provided with: ...
178 views

### How can I break this encryption scheme?

Let $p$ be a large public prime. Alice holds a private key $(e_1,d_1) \in Z_{p-1}^*$ such that $e_1 d_1 = 1 \mod {p-1}$. Bob also holds a different private key $(e_2,d_2)$ with the same property. ...
81 views

### Why is this authentication procedure using Rabin crypto not useful?

A friend asked me the following, pointing out that the method is not very useful (my problem is I do not see why it is not good): Consider a person A which chooses $n$ as the public key for the ...
110 views

### Encrypting a TCP connection between two unknown nodes

I'm writing an application for controlling computers from a client. I'd very much like it if the connection is secure and only authenticated clients are allowed access. The workflow will be ...
120 views

### AES: Is it safe to encrypt same cleartext with same key but with million diferent IV?

The encryption mode that I am using is CBC. Algorithm is AES and the key size is 128bit. I will be encrypting a 36 byte string over 1.3 million times with the same key but with a random IV. My ...