iaik.security.dsa

Class SHA224withDSAKeyPairGenerator

java.lang.Object

java.security.KeyPairGeneratorSpi

java.security.KeyPairGenerator

iaik.security.dsa.DSAKeyPairGenerator

iaik.security.dsa.SHA224withDSAKeyPairGenerator

All Implemented Interfaces:

java.security.interfaces.DSAKeyPairGenerator

public class SHA224withDSAKeyPairGenerator
extends DSAKeyPairGenerator

SHA-224 based DSA key pair generator as specified in FIPS PUB 186-3.

FIPS 186-3 (June 2009) updates the DSA digital signature algorithm for use with SHA-2 hash algorithms. It defines four (L,N) (prime modulus length, prime divisor length) parameter sets for moduli of lengths 1024, 2048 and 3072:

• 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.

This DSA key pair generator allows to generate 1024 and 2048 bit key pairs.

When initializing this key pair generator you explicitly may specify the set of domain parameters (p, q, g) to be used, e.g.:

 DSAParameterSpec dsaParamSpec = ...;
 KeyPairGenerator dsaKeyGen = KeyPairGenerator.getInstance("SHA224withDSA", "IAIK");
 dsaKeyGen.initialize(dsaParamSpec);
 KeyPair keyPair = dsaKeyGen.generateKeyPair();
 

Alternatively you may only specify the length (in bits) of the key pair to be generated. In this case default parameters for the requested modulus length are used (with L,N pairs 1024,160 or 2048,224), e.g.:

 KeyPairGenerator dsaKeyGen = KeyPairGenerator.getInstance("SHA224withDSA", "IAIK");
 dsaKeyGen.initialize(2048);
 KeyPair keyPair = dsaKeyGen.generateKeyPair();
 

The IAIK provider also allows to tell this DSA KeyPairGenerator to generate new domain parameters. However, in this case you must cast to the IAIK DSAKeyPairGenerator, e.g.:

 SHA224withDSAKeyPairGenerator dsaKeyGen = 
   (SHA224withDSAKeyPairGenerator)KeyPairGenerator.getInstance("SHA224withDSA", "IAIK");
 boolean generateNewParameters = true;
 SecureRansom random = ...;  
 dsaKeyGen.initialize(2048, generateNewParameters, random);
 KeyPair keyPair = dsaKeyGen.generateKeyPair();
 

If the KeyPairGenerator is used without calling an initialize method at all, 2048 bit keys are generated (L = 2048, N = 224), , e.g.:

 KeyPairGenerator dsaKeyGen = KeyPairGenerator.getInstance("SHA224withDSA", "IAIK");
 KeyPair keyPair = dsaKeyGen.generateKeyPair();
 

Version:

File Revision 2

See Also:

SHA256withDSAKeyPairGenerator, DSAPublicKey, DSAPrivateKey, DSAParams

Constructor Summary

Constructors

Constructor and Description
SHA224withDSAKeyPairGenerator() Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	initialize(int modlen) Initializes this DSAKeyPairGenerator for given prime modulus length.
void	initialize(int modlen, boolean genParams, java.security.SecureRandom random) Initializes this DSAKeyPairGenerator for given modulus length with the given random seed.
void	initialize(int modlen, java.security.SecureRandom random) Initializes this DSAKeyPairGenerator for given prime modulus length with the given random seed.

Methods inherited from class iaik.security.dsa.DSAKeyPairGenerator

generateKeyPair, initialize, initialize

Methods inherited from class java.security.KeyPairGenerator

genKeyPair, getAlgorithm, getInstance, getInstance, getInstance, getProvider, initialize

Methods inherited from class java.lang.Object

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

Constructor Detail

SHA224withDSAKeyPairGenerator

public SHA224withDSAKeyPairGenerator()

Default constructor.

Method Detail

initialize

public void initialize(int modlen)

Initializes this DSAKeyPairGenerator for given prime modulus length.

Overrides:

initialize in class DSAKeyPairGenerator

Parameters:

modlen - the desired length (in bits) of the prime modulus (1024 or 2048)

Throws:

java.lang.IllegalArgumentException - if the requested modulus length is not 1024 or 2048

initialize

public void initialize(int modlen,
              java.security.SecureRandom random)

Initializes this DSAKeyPairGenerator for given prime modulus length with the given random seed.

Overrides:

initialize in class DSAKeyPairGenerator

Parameters:

modlen - the desired length (in bits) of the prime modulus (1024 or 2048)

random - the random seed as SecureRandom

Throws:

java.lang.IllegalArgumentException - if the requested modulus length is not 1024 or 2048

initialize

public void initialize(int modlen,
              boolean genParams,
              java.security.SecureRandom random)
                throws java.security.InvalidParameterException

Initializes this DSAKeyPairGenerator for given modulus length with the given random seed. This method initializes the generator either with precomputed DSA parameter values p, q and g (when genParams is set to false), or by generating new DSA parameter values (when genParams is set to true). Precomputed parameters are available for modulus length of either 1024 or 2048 bits.

Specified by:

initialize in interface java.security.interfaces.DSAKeyPairGenerator

Overrides:

initialize in class DSAKeyPairGenerator

Parameters:

modlen - the length of the modulus in bits (1024 or 2048)

genParams - true for generating new parameters, false for using precomputed values for p, q and g

random - the random seed as SecureRandom

Throws:

java.security.InvalidParameterException - if the given modulus length is not 1024, 2048 or 3072