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package java.security.interfaces;

import java.security.*;


An interface to an object capable of generating DSA key pairs.

The initialize methods may each be called any number of times. If no initialize method is called on a DSAKeyPairGenerator, each provider that implements this interface should supply (and document) a default initialization. Note that defaults may vary across different providers. Additionally, the default value for a provider may change in a future version. Therefore, it is recommended to explicitly initialize the DSAKeyPairGenerator instead of relying on provider-specific defaults. 
Users wishing to indicate DSA-specific parameters, and to generate a key
pair suitable for use with the DSA algorithm typically

    

  1. Get a key pair generator for the DSA algorithm by calling the KeyPairGenerator getInstance method with "DSA" as its argument. 
  2. Check if the returned key pair generator is an instance of DSAKeyPairGenerator before casting the result to a DSAKeyPairGenerator and calling one of the initialize methods from this DSAKeyPairGenerator interface. 
  3. Generate a key pair by calling the generateKeyPair method of the KeyPairGenerator class. 


Note: it is not always necessary to do algorithm-specific initialization for a DSA key pair generator. That is, it is not always necessary to call an initialize method in this interface. Algorithm-independent initialization using the initialize method in the KeyPairGenerator interface is all that is needed when you accept defaults for algorithm-specific parameters. 
Note: Some earlier implementations of this interface may not support
larger values of DSA parameters such as 3072-bit.

See Also:
Since:1.1
/**
 * An interface to an object capable of generating DSA key pairs.
 *
 * <p>The {@code initialize} methods may each be called any number
 * of times. If no {@code initialize} method is called on a
 * DSAKeyPairGenerator, each provider that implements this interface
 * should supply (and document) a default initialization. Note that
 * defaults may vary across different providers. Additionally, the default
 * value for a provider may change in a future version. Therefore, it is
 * recommended to explicitly initialize the DSAKeyPairGenerator instead
 * of relying on provider-specific defaults.
 *
 * <p>Users wishing to indicate DSA-specific parameters, and to generate a key
 * pair suitable for use with the DSA algorithm typically
 *
 * <ol>
 *
 * <li>Get a key pair generator for the DSA algorithm by calling the
 * KeyPairGenerator {@code getInstance} method with "DSA"
 * as its argument.
 *
 * <li>Check if the returned key pair generator is an instance of
 * DSAKeyPairGenerator before casting the result to a DSAKeyPairGenerator
 * and calling one of the {@code initialize} methods from this
 * DSAKeyPairGenerator interface.
 *
 * <li>Generate a key pair by calling the {@code generateKeyPair}
 * method of the KeyPairGenerator class.
 *
 * </ol>
 *
 * <p>Note: it is not always necessary to do algorithm-specific
 * initialization for a DSA key pair generator. That is, it is not always
 * necessary to call an {@code initialize} method in this interface.
 * Algorithm-independent initialization using the {@code initialize} method
 * in the KeyPairGenerator
 * interface is all that is needed when you accept defaults for algorithm-specific
 * parameters.
 *
 * <p>Note: Some earlier implementations of this interface may not support
 * larger values of DSA parameters such as 3072-bit.
 *
 * @since 1.1
 * @see java.security.KeyPairGenerator
 */
public interface DSAKeyPairGenerator {

    
Initializes the key pair generator using the DSA family parameters
(p,q and g) and an optional SecureRandom bit source. If a
SecureRandom bit source is needed but not supplied, i.e. null, a
default SecureRandom instance will be used.

Params:
  • params – the parameters to use to generate the keys.
  • random – the random bit source to use to generate key bits;
can be null.
Throws:
/**
     * Initializes the key pair generator using the DSA family parameters
     * (p,q and g) and an optional SecureRandom bit source. If a
     * SecureRandom bit source is needed but not supplied, i.e. null, a
     * default SecureRandom instance will be used.
     *
     * @param params the parameters to use to generate the keys.
     *
     * @param random the random bit source to use to generate key bits;
     * can be null.
     *
     * @exception InvalidParameterException if the {@code params}
     * value is invalid, null, or unsupported.
     */
   public void initialize(DSAParams params, SecureRandom random)
   throws InvalidParameterException;

    
Initializes the key pair generator for a given modulus length
(instead of parameters), and an optional SecureRandom bit source.
If a SecureRandom bit source is needed but not supplied, i.e.
null, a default SecureRandom instance will be used.

If genParams is true, this method generates new p, q and g parameters. If it is false, the method uses precomputed parameters for the modulus length requested. If there are no precomputed parameters for that modulus length, an exception will be thrown. 
Params:
  • modlen – the modulus length in bits. Valid values are any
multiple of 64 between 512 and 1024, inclusive, 2048, and 3072.
  • random – the random bit source to use to generate key bits;
can be null.
  • genParams – whether or not to generate new parameters for
the modulus length requested.
Throws:
  • InvalidParameterException – if modlen is invalid, or unsupported, or if genParams is false and there are no precomputed parameters for the requested modulus length.
/**
     * Initializes the key pair generator for a given modulus length
     * (instead of parameters), and an optional SecureRandom bit source.
     * If a SecureRandom bit source is needed but not supplied, i.e.
     * null, a default SecureRandom instance will be used.
     *
     * <p>If {@code genParams} is true, this method generates new
     * p, q and g parameters. If it is false, the method uses precomputed
     * parameters for the modulus length requested. If there are no
     * precomputed parameters for that modulus length, an exception will be
     * thrown.
     *
     * @param modlen the modulus length in bits. Valid values are any
     * multiple of 64 between 512 and 1024, inclusive, 2048, and 3072.
     *
     * @param random the random bit source to use to generate key bits;
     * can be null.
     *
     * @param genParams whether or not to generate new parameters for
     * the modulus length requested.
     *
     * @exception InvalidParameterException if {@code modlen} is
     * invalid, or unsupported, or if {@code genParams} is false and there
     * are no precomputed parameters for the requested modulus length.
     */
    public void initialize(int modlen, boolean genParams, SecureRandom random)
    throws InvalidParameterException;
}