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package java.security.interfaces;
import java.security.*;
/**
* An interface to an object capable of generating DSA key pairs.
*
* <p>The <code>initialize</code> methods may each be called any number
* of times. If no <code>initialize</code> method is called on a
* DSAKeyPairGenerator, the default is to generate 1024-bit keys, using
* precomputed p, q and g parameters and an instance of SecureRandom as
* the random bit source.
*
* <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</code> method with "DSA"
* as its argument.<p>
*
* <li>Initialize the generator by casting the result to a DSAKeyPairGenerator
* and calling one of the
* <code>initialize</code> methods from this DSAKeyPairGenerator interface.<p>
*
* <li>Generate a key pair by calling the <code>generateKeyPair</code>
* method from the KeyPairGenerator class.
*
* </ol>
*
* <p>Note: it is not always necessary to do do algorithm-specific
* initialization for a DSA key pair generator. That is, it is not always
* necessary to call an <code>initialize</code> method in this interface.
* Algorithm-independent initialization using the <code>initialize</code> method
* in the KeyPairGenerator
* interface is all that is needed when you accept defaults for algorithm-specific
* parameters.
*
* @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.
*
* @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</code>
* value is invalid or null.
*/
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.
*
* <p>If <code>genParams</code> 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. It is guaranteed that there will always be
* default parameters for modulus lengths of 512 and 1024 bits.
*
* @param modlen the modulus length in bits. Valid values are any
* multiple of 8 between 512 and 1024, inclusive.
*
* @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</code> is not
* between 512 and 1024, or if <code>genParams</code> is false and
* there are no precomputed parameters for the requested modulus
* length.
*/
public void initialize(int modlen, boolean genParams, SecureRandom random)
throws InvalidParameterException;
}