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package com.sun.crypto.provider;

import java.io.*;
import sun.security.util.*;
import java.math.BigInteger;
import java.security.AlgorithmParametersSpi;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidParameterSpecException;
import javax.crypto.spec.DHParameterSpec;

This class implements the parameter set used by the Diffie-Hellman key agreement as defined in the PKCS #3 standard.
Author:Jan Luehe
/** * This class implements the parameter set used by the * Diffie-Hellman key agreement as defined in the PKCS #3 standard. * * @author Jan Luehe * */
public final class DHParameters extends AlgorithmParametersSpi { // The prime (p). private BigInteger p = BigInteger.ZERO; // The base (g). private BigInteger g = BigInteger.ZERO; // The private-value length (l) private int l = 0; protected void engineInit(AlgorithmParameterSpec paramSpec) throws InvalidParameterSpecException { if (!(paramSpec instanceof DHParameterSpec)) { throw new InvalidParameterSpecException ("Inappropriate parameter specification"); } this.p = ((DHParameterSpec)paramSpec).getP(); this.g = ((DHParameterSpec)paramSpec).getG(); this.l = ((DHParameterSpec)paramSpec).getL(); } protected void engineInit(byte[] params) throws IOException { try { DerValue encodedParams = new DerValue(params); if (encodedParams.tag != DerValue.tag_Sequence) { throw new IOException("DH params parsing error"); } encodedParams.data.reset(); this.p = encodedParams.data.getBigInteger(); this.g = encodedParams.data.getBigInteger(); // Private-value length is OPTIONAL if (encodedParams.data.available() != 0) { this.l = encodedParams.data.getInteger(); } if (encodedParams.data.available() != 0) { throw new IOException ("DH parameter parsing error: Extra data"); } } catch (NumberFormatException e) { throw new IOException("Private-value length too big"); } } protected void engineInit(byte[] params, String decodingMethod) throws IOException { engineInit(params); } protected <T extends AlgorithmParameterSpec> T engineGetParameterSpec(Class<T> paramSpec) throws InvalidParameterSpecException { if (DHParameterSpec.class.isAssignableFrom(paramSpec)) { return paramSpec.cast(new DHParameterSpec(this.p, this.g, this.l)); } else { throw new InvalidParameterSpecException ("Inappropriate parameter Specification"); } } protected byte[] engineGetEncoded() throws IOException { DerOutputStream out = new DerOutputStream(); DerOutputStream bytes = new DerOutputStream(); bytes.putInteger(this.p); bytes.putInteger(this.g); // Private-value length is OPTIONAL if (this.l > 0) { bytes.putInteger(this.l); } out.write(DerValue.tag_Sequence, bytes); return out.toByteArray(); } protected byte[] engineGetEncoded(String encodingMethod) throws IOException { return engineGetEncoded(); } /* * Returns a formatted string describing the parameters. */ protected String engineToString() { String LINE_SEP = System.getProperty("line.separator"); StringBuilder sb = new StringBuilder("SunJCE Diffie-Hellman Parameters:" + LINE_SEP + "p:" + LINE_SEP + Debug.toHexString(this.p) + LINE_SEP + "g:" + LINE_SEP + Debug.toHexString(this.g)); if (this.l != 0) sb.append(LINE_SEP + "l:" + LINE_SEP + " " + this.l); return sb.toString(); } }