/* GnuRSAPrivateKey.java -- 
   Copyright 2001, 2002, 2003, 2006 Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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package gnu.java.security.key.rsa;

import gnu.classpath.SystemProperties;
import gnu.java.security.Registry;
import gnu.java.security.key.IKeyPairCodec;

import java.math.BigInteger;
import java.security.PrivateKey;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPrivateKey;

/**
 * <p>An object that embodies an RSA private key.</p>
 *
 * <p>References:</p>
 * <ol>
 *    <li><a href="http://www.cosic.esat.kuleuven.ac.be/nessie/workshop/submissions/rsa-pss.zip">
 *    RSA-PSS Signature Scheme with Appendix, part B.</a><br>
 *    Primitive specification and supporting documentation.<br>
 *    Jakob Jonsson and Burt Kaliski.</li>
 * </ol>
 */
public class GnuRSAPrivateKey extends GnuRSAKey implements PrivateKey,
    RSAPrivateCrtKey
{
  // Constants and variables
  // -------------------------------------------------------------------------

  private static final boolean DEBUG = false;

  /** The first prime divisor of the modulus. */
  private final BigInteger p;

  /** The second prime divisor of the modulus. */
  private final BigInteger q;

  /** The public exponent of an RSA key. */
  //   private final BigInteger e;
  /** The private exponent of an RSA private key. */
  private final BigInteger d;

  /** The first factor's exponent. */
  private final BigInteger dP;

  /** The second factor's exponent. */
  private final BigInteger dQ;

  /** The CRT (Chinese Remainder Theorem) coefficient. */
  private final BigInteger qInv;

  /** String representation of this key. Cached for speed. */
  private transient String str;

  // Constructor(s)
  // -------------------------------------------------------------------------

  /**
   * Convenience constructor. Calls the constructor with 5 arguments passing
   * {@link Registry#RAW_ENCODING_ID} as the identifier of the preferred
   * encoding format.
   *
   * @param p the modulus first prime divisor.
   * @param q the modulus second prime divisor.
   * @param e the public exponent.
   * @param d the private exponent.
   */
  public GnuRSAPrivateKey(BigInteger p, BigInteger q, BigInteger e,
                          BigInteger d)
  {
    this(Registry.RAW_ENCODING_ID, p, q, e, d);
  }

  /**
   * Constructs a new instance of a <code>GnuRSAPrivateKey</code> given the
   * designated arguments.
   * 
   * @param preferredFormat the indetifier of the preferred encoding format to
   *          use when externalizing this key.
   * @param p the modulus first prime divisor.
   * @param q the modulus second prime divisor.
   * @param e the public exponent.
   * @param d the private exponent.
   */
  public GnuRSAPrivateKey(int preferredFormat, BigInteger p, BigInteger q,
                          BigInteger e, BigInteger d)
  {
    this(preferredFormat, p.multiply(q), e, d, p, q, 
         e.modInverse(p.subtract(BigInteger.ONE)),
         e.modInverse(q.subtract(BigInteger.ONE)),
         q.modInverse(p));
  }

  /**
   * Constructs a new instance of a <code>GnuRSAPrivateKey</code> given the
   * designated arguments.
   * 
   * @param preferredFormat the indetifier of the preferred encoding format to
   *          use when externalizing this key.
   * @param n the public modulus, which is also the product of <code>p</code>
   * and <code>q</code>.
   * @param e the public exponent.
   * @param d the private exponent.
   * @param p the modulus first prime divisor.
   * @param q the modulus second prime divisor.
   * @param dP the first prime's exponen. A positive integer less than
   * <code>p</code> and <code>q</code>, satisfying <code>e * dP = 1 (mod p-1)
   * </code>.
   * @param dQ the second prime's exponent. A positive integer less than
   * <code>p</code> and <code>q</code>, satisfying <code>e * dQ = 1 (mod p-1)
   * </code>.
   * @param qInv the Chinese Remainder Theorem coefiicient. A positive integer
   * less than <code>p</code>, satisfying <code>q * qInv = 1 (mod p)</code>.
   */
  public GnuRSAPrivateKey(int preferredFormat, BigInteger n, BigInteger e,
                          BigInteger d, BigInteger p, BigInteger q,
                          BigInteger dP, BigInteger dQ, BigInteger qInv)
  {
    super(preferredFormat == Registry.ASN1_ENCODING_ID ? Registry.PKCS8_ENCODING_ID
                                                       : preferredFormat,
          n, e);

    this.d = d;
    this.p = p;
    this.q = q;
    // the exponents dP and dQ are positive integers less than p and q
    // respectively satisfying
    //    e * dP = 1 (mod p-1);
    //    e * dQ = 1 (mod q-1),
    this.dP = dP;
    this.dQ = dQ;
    // the CRT coefficient qInv is a positive integer less than p satisfying
    //    q * qInv = 1 (mod p).
    this.qInv = qInv;
  }

  // Class methods
  // -------------------------------------------------------------------------

  /**
   * A class method that takes the output of the <code>encodePrivateKey()</code>
   * method of an RSA keypair codec object (an instance implementing
   * {@link IKeyPairCodec} for RSA keys, and re-constructs an instance of this
   * object.
   * 
   * @param k the contents of a previously encoded instance of this object.
   * @throws ArrayIndexOutOfBoundsException if there is not enough bytes, in
   *           <code>k</code>, to represent a valid encoding of an instance
   *           of this object.
   * @throws IllegalArgumentException if the byte sequence does not represent a
   *           valid encoding of an instance of this object.
   */
  public static GnuRSAPrivateKey valueOf(final byte[] k)
  {
    // try RAW codec
    if (k[0] == Registry.MAGIC_RAW_RSA_PRIVATE_KEY[0])
      try
        {
          return (GnuRSAPrivateKey) new RSAKeyPairRawCodec().decodePrivateKey(k);
        }
      catch (IllegalArgumentException ignored)
        {
        }

    // try PKCS#8 codec
    return (GnuRSAPrivateKey) new RSAKeyPairPKCS8Codec().decodePrivateKey(k);
  }

  // Instance methods
  // -------------------------------------------------------------------------

  public BigInteger getPrimeP()
  {
    return p;
  }

  public BigInteger getPrimeQ()
  {
    return q;
  }

  public BigInteger getPrimeExponentP()
  {
    return dP;
  }

  public BigInteger getPrimeExponentQ()
  {
    return dQ;
  }

  public BigInteger getCrtCoefficient()
  {
    return qInv;
  }

  // java.security.interfaces.RSAPrivateKey interface implementation ---------

  public BigInteger getPrivateExponent()
  {
    return d;
  }

  // Other instance methods --------------------------------------------------

  /**
   * Returns the encoded form of this private key according to the
   * designated format.
   *
   * @param format the desired format identifier of the resulting encoding.
   * @return the byte sequence encoding this key according to the designated
   * format.
   * @throws IllegalArgumentException if the format is not supported.
   * @see RSAKeyPairRawCodec
   * @see RSAKeyPairPKCS8Codec
   */
  public byte[] getEncoded(int format)
  {
    final byte[] result;
    switch (format)
      {
      case IKeyPairCodec.RAW_FORMAT:
        result = new RSAKeyPairRawCodec().encodePrivateKey(this);
        break;
      case IKeyPairCodec.PKCS8_FORMAT:
        result = new RSAKeyPairPKCS8Codec().encodePrivateKey(this);
        break;
      default:
        throw new IllegalArgumentException("Unsupported encoding format: "
                                           + format);
      }
    return result;
  }

  /**
   * <p>Returns <code>true</code> if the designated object is an instance of
   * this class and has the same RSA parameter values as this one.</p>
   *
   * @param obj the other non-null RSA key to compare to.
   * @return <code>true</code> if the designated object is of the same type
   * and value as this one.
   */
  public boolean equals(final Object obj)
  {
    if (obj == null)
      {
        return false;
      }
    if (obj instanceof RSAPrivateKey)
      {
        final RSAPrivateKey that = (RSAPrivateKey) obj;
        return super.equals(that) && d.equals(that.getPrivateExponent());
      }
    if (obj instanceof RSAPrivateCrtKey)
      {
        final RSAPrivateCrtKey that = (RSAPrivateCrtKey) obj;
        return super.equals(that) && p.equals(that.getPrimeP())
               && q.equals(that.getPrimeQ())
               && dP.equals(that.getPrimeExponentP())
               && dQ.equals(that.getPrimeExponentQ())
               && qInv.equals(that.getCrtCoefficient());
      }
    return false;
  }

  public String toString()
  {
    if (str == null)
      {
        String ls = SystemProperties.getProperty("line.separator");
        str = new StringBuilder(this.getClass().getName()).append("(")
            .append(super.toString()).append(",").append(ls)
            .append("d=0x").append(DEBUG ? d.toString(16) : "**...*").append(ls)
            .append("p=0x").append(DEBUG ? p.toString(16) : "**...*").append(ls)
            .append("q=0x").append(DEBUG ? q.toString(16) : "**...*").append(ls)
            .append("dP=0x").append(DEBUG ? dP.toString(16) : "**...*").append(ls)
            .append("dQ=0x").append(DEBUG ? dQ.toString(16) : "**...*").append(ls)
            .append("qInv=0x").append(DEBUG ? qInv.toString(16) : "**...*").append(ls)
            .append(")").toString();
      }
    return str;
  }
}
