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package org.spongycastle.jcajce.provider.asymmetric.dsa;

import java.io.IOException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.DSAParameterSpec;
import java.security.spec.InvalidParameterSpecException;

import org.spongycastle.asn1.ASN1Encoding;
import org.spongycastle.asn1.ASN1Primitive;
import org.spongycastle.asn1.x509.DSAParameter;

public class AlgorithmParametersSpi
    extends java.security.AlgorithmParametersSpi
{
    DSAParameterSpec currentSpec;

    protected boolean isASN1FormatString(String format)
    {
        return format == null || format.equals("ASN.1");
    }

    protected AlgorithmParameterSpec engineGetParameterSpec(
        Class paramSpec)
        throws InvalidParameterSpecException
    {
        if (paramSpec == null)
        {
            throw new NullPointerException("argument to getParameterSpec must not be null");
        }

        return localEngineGetParameterSpec(paramSpec);
    }

    /**
     * Return the X.509 ASN.1 structure DSAParameter.
     * 
     *  DSAParameter ::= SEQUENCE {
     *                   prime INTEGER, -- p
     *                   subprime INTEGER, -- q
     *                   base INTEGER, -- g}
     * 
*/ protected byte[] engineGetEncoded() { DSAParameter dsaP = new DSAParameter(currentSpec.getP(), currentSpec.getQ(), currentSpec.getG()); try { return dsaP.getEncoded(ASN1Encoding.DER); } catch (IOException e) { throw new RuntimeException("Error encoding DSAParameters"); } } protected byte[] engineGetEncoded( String format) { if (isASN1FormatString(format)) { return engineGetEncoded(); } return null; } protected AlgorithmParameterSpec localEngineGetParameterSpec( Class paramSpec) throws InvalidParameterSpecException { if (paramSpec == DSAParameterSpec.class || paramSpec == AlgorithmParameterSpec.class) { return currentSpec; } throw new InvalidParameterSpecException("unknown parameter spec passed to DSA parameters object."); } protected void engineInit( AlgorithmParameterSpec paramSpec) throws InvalidParameterSpecException { if (!(paramSpec instanceof DSAParameterSpec)) { throw new InvalidParameterSpecException("DSAParameterSpec required to initialise a DSA algorithm parameters object"); } this.currentSpec = (DSAParameterSpec)paramSpec; } protected void engineInit( byte[] params) throws IOException { try { DSAParameter dsaP = DSAParameter.getInstance(ASN1Primitive.fromByteArray(params)); currentSpec = new DSAParameterSpec(dsaP.getP(), dsaP.getQ(), dsaP.getG()); } catch (ClassCastException e) { throw new IOException("Not a valid DSA Parameter encoding."); } catch (ArrayIndexOutOfBoundsException e) { throw new IOException("Not a valid DSA Parameter encoding."); } } protected void engineInit( byte[] params, String format) throws IOException { if (isASN1FormatString(format) || format.equalsIgnoreCase("X.509")) { engineInit(params); } else { throw new IOException("Unknown parameter format " + format); } } protected String engineToString() { return "DSA Parameters"; } }




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