cryptix.provider.elgamal
Class GenericElGamalParameterSet
java.lang.Object
cryptix.provider.elgamal.GenericElGamalParameterSet
public class GenericElGamalParameterSet
extends java.lang.Object
This class represents a set of ElGamal parameters for various prime lengths.
The best methods for computing discrete logarithms in GF(p) have an expensive
pre-computation stage, but once the pre-computation has been done, individual
logarithms can be calculated quickly. In order to make sure that a particular
set of parameters does not become too much of a target because it is used in
more than one application, you may wish to generate your own set of parameters.
References:
- Bruce Schneier,
"Section 11.3 Number Theory" (heading "Calculating Discrete Logarithms
in a Finite Group," pages 262-263),
Applied Cryptography, 2nd edition,
John Wiley & Sons, 1996.
Copyright © 1997
Systemics Ltd on behalf of the
Cryptix Development Team.
All rights reserved.
$Revision: 1.4 $
cryptix.examples.CreateElGamalParameterSet
, cryptix.security.elgamal.BaseElGamalKeyPairGenerator
GenericElGamalParameterSet(int[] primeLengths, String[][] precomputed) - Subclasses should call this constructor to determine the parameters
that will be returned by
getParameters .
|
void | checkSane() - Throws an InvalidParameterException if any of the parameters are obviously
incorrect.
|
ElGamalParams | getParameters(int primeLength) - If primeLength corresponds to one of the precomputed prime lengths,
this method returns a corresponding ElGamalParams object.
|
GenericElGamalParameterSet
protected GenericElGamalParameterSet(int[] primeLengths,
String[][] precomputed)
Subclasses should call this constructor to determine the parameters
that will be returned by getParameters
.
primeLengths
- an array of bit lengths for each prime
checkSane
public void checkSane()
throws InvalidParameterException
Throws an InvalidParameterException if any of the parameters are obviously
incorrect.
getParameters
public ElGamalParams getParameters(int primeLength)
If primeLength corresponds to one of the precomputed prime lengths,
this method returns a corresponding ElGamalParams object. Otherwise,
it returns null.