iaik.security.dsa

Class SHA2withDSAGenParameterSpec

java.lang.Object

iaik.security.dsa.SHA2withDSAGenParameterSpec

All Implemented Interfaces:

java.security.spec.AlgorithmParameterSpec

public class SHA2withDSAGenParameterSpec
extends java.lang.Object
implements java.security.spec.AlgorithmParameterSpec

DSA generation parameter specification.

This class represents a DSA generation parameter specification to be used with a DSA FIPS 186-3 AlgorithmParameterGenerator for generating DSA parameters p, q and r (prime modulus, prime divisor and generator, respectively). This class allows to specify the desired length L of the prime modulus and the desired length N of the prime divisor.

FIPS 186-3 (June 2009) allows the following (L,N) pairs to may be used:

• L = 1024, N = 160
• L = 2048, N = 224
• L = 2048, N = 256
• L = 3072, N = 256

AlgorithmIdentfiers for DSA with SHA-224 and SHA-256 are specified in draft-ietf-pkix-sha2-dsa-ecdsa-06.txt. SHA-224 may be used with (1024,160) and (2048,224) L,N pairs only, SHA-256 may be used with any of the four L,N pairs.

When using a SHA2withDSAGenParameterSpec with and DSA SHA-2 AlgorithmParameterGenerator you have to specify which L,N pair you want to use, e.g.:

 int L = 3072;
 int N = 256;
 SHA2withDSAGenParameterSpec genParamSpec = new SHA2withDSAGenParameterSpec(L, N);
 AlgorithmParameterGenerator generator = 
   AlgorithmParameterGenerator.getInstance("SHA256withDSA", "IAIK");
 SecureRandom random = ...;
 generator.init(genParamSpec, random);
 AlgortithmParameters params = generator.generateParameters(); 
 

Version:

File Revision 3

Constructor Summary

Constructors

Constructor and Description
SHA2withDSAGenParameterSpec(int L, int N) Creates a DSA generation parameter specification with the given prime modulus size and prime divisor size.

Method Summary

Methods

Modifier and Type	Method and Description
int	getL() Returns the prime modulus size in bits.
int	getN() Returns the prime divisor size in bits.
int	getSeedlen() Gets the seed length.
void	setSeedlen(int seedlen) Sets the seed length to be used.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SHA2withDSAGenParameterSpec

public SHA2withDSAGenParameterSpec(int L,
                           int N)
                            throws java.lang.IllegalArgumentException

Creates a DSA generation parameter specification with the given prime modulus size and prime divisor size. FIPS 186-3 (June 2009) allows the following prime modulus, prime divisor (L,N) pairs to may be used:

• L = 1024, N = 160
• L = 2048, N = 224
• L = 2048, N = 256
• L = 3072, N = 256

Parameters:

L - the prime modulus size in bits

N - the prime divisor size in bits

Throws:

java.lang.IllegalArgumentException - if (L,N) is not a valid L, N pair according section 4.2 of FIPS PUB 186-3 (valid pairs are (1024,160), (2048,224), (2048,256), (3072, 256))

Method Detail

setSeedlen

public void setSeedlen(int seedlen)

Sets the seed length to be used. It shall be equal or greater than the length of the prime divisor N and (for this implemenation shall be a multiple of 8).

Parameters:

seedlen - the lenth of the seed, in bits

Throws:

java.lang.IllegalArgumentException - if the seedlen value is shorter than N or is not a multiple of 8

getL

public int getL()

Returns the prime modulus size in bits.

Returns:

the prime modulus size in bits

getN

public int getN()

Returns the prime divisor size in bits.

Returns:

the prime divisor size in bits

getSeedlen

public int getSeedlen()

Gets the seed length.

Returns:

the seed length, or -1 if not set