# All Questions

63 views

### Secret sharing - no dealer, modifiable, verifiable

I need to find a secret sharing scheme with these properties: The scheme is set up by all participants, ie no single entity called the dealer The parameters of secret sharing need to be ...
102 views

### Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$

Suppose you want to select a prime $p$ such that finding e.g. $log_2(3)$ in $\mathbb{Z}_p$ is expected to be either at least as hard as the general Discrete Logarithm Problem in $\mathbb{Z}_p$, or at ...
60 views

### cryptography permutation [closed]

Let $\pi$ be a permutation of the integers $0$ through $2^n-1$ (the integers that can be represented in $n$ bits). For example, $\pi$ could be used as a substitution cipher in which each plaintext ...
101 views

### One-way function and uninvertible function [closed]

How can I prove the following : "if f is a one-way function, then it is an uninvertible function" ??
137 views

### Z*p Generator (Cyclic Group) in java

I am trying to implement ElGamal in java without using the in-built libraries. The problem occurs when I am trying to find the generators of the number(in this case 11). Everything works perfectly ...
65 views

### ElGamal encryption with private key [closed]

Does the encryption with a private key and decryption with a public key works in ElGamal likewise what is done when we use RSA for sender authentication?
142 views

### Avoiding overflow when encrypting with RSA

When encrypting with RSA one calculates $m^e \pmod n$ by doing the following: m^e % n Where $m$ is what we encrypt. Often $e$ is a very big number to make it ...
111 views

### Generating bilinear pairing parameters - running time of finding member of p-torsion group

Update: Question completely rephrased. I want to create the parameters for a bilinear pairing (the Tate pairing in this case). In case you're interested I'm following this thesis, specifically the ...
65 views

### Method to calculating e in RSA

For simplicity I choose two small primes for p and q. p=3 q=11 n=33 Φ(n)=20 Now we need ...
94 views

### Why do we use 1024 / 160 bit primes in DSA?

I am looking at DSA's parameter generation and don't understand why for $p$ a 1024 bit prime is needed if $q$ is chosen as a $160$ bit prime. I thought that the security of DSA relates on the discrete ...
122 views

### Predicting Java's PRNG using partial output

I have a program (a game) that uses Java's nextInt function with parameter 0x10000 to get a random 16-bit number. Java's ...
34 views

### Would requiring reciprocal signatures create a stronger Web of Trust?

In this post on Cryptome it's noted that a person called Michael Vario is willy-nilly signing people's public key's and uploading those signatures. He is effectively forging a web of trust. I'm sure ...
45 views

### Choice of reduction polynomial in Whirlpool's internal cipher

Whirlpool is an interesting little hash function in the Miyaguchi-Preneel family. In my mind, it's most interesting feature is the design of internal cipher W, where the distinction between key and ...
99 views

### Cryptanalysis of an certain algorithm

Is an attacker of an cryptographic algorithm allowed to change order of sub-keys but not changing their number in attack? Would it be called an attack on broken algorithm of cipher?
282 views

### How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?

If cryptanalysts today were to crack the original Enigma machine, how fast/ how easily could they do it? What methods would they use? The original cracking was significantly helped by operator ...