/*
 * Copyright (c) 2015-2018 ymnk, JCraft,Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
 * and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The names of the authors may not be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL JCRAFT, INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jcraft.jsch.jce;

import com.jcraft.jsch.JSchException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.ECPrivateKey;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECGenParameterSpec;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;

public class KeyPairGenECDSA implements com.jcraft.jsch.KeyPairGenECDSA {
  byte[] d;
  byte[] r;
  byte[] s;
  ECPublicKey pubKey;
  ECPrivateKey prvKey;
  ECParameterSpec params;

  @Override
  public void init(int key_size) throws Exception {
    String name = null;
    if (key_size == 256)
      name = "secp256r1";
    else if (key_size == 384)
      name = "secp384r1";
    else if (key_size == 521)
      name = "secp521r1";
    else
      throw new JSchException("unsupported key size: " + key_size);

    for (int i = 0; i < 1000; i++) {
      KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC");
      ECGenParameterSpec ecsp = new ECGenParameterSpec(name);
      kpg.initialize(ecsp);
      KeyPair kp = kpg.genKeyPair();
      prvKey = (ECPrivateKey) kp.getPrivate();
      pubKey = (ECPublicKey) kp.getPublic();
      params = pubKey.getParams();
      d = prvKey.getS().toByteArray();
      ECPoint w = pubKey.getW();
      r = w.getAffineX().toByteArray();
      s = w.getAffineY().toByteArray();

      if (r.length != s.length)
        continue;
      if (key_size == 256 && r.length == 32)
        break;
      if (key_size == 384 && r.length == 48)
        break;
      if (key_size == 521 && r.length == 66)
        break;
    }
    if (d.length < r.length) {
      d = insert0(d);
    }
  }

  @Override
  public byte[] getD() {
    return d;
  }

  @Override
  public byte[] getR() {
    return r;
  }

  @Override
  public byte[] getS() {
    return s;
  }

  ECPublicKey getPublicKey() {
    return pubKey;
  }

  ECPrivateKey getPrivateKey() {
    return prvKey;
  }

  private byte[] insert0(byte[] buf) {
    // if ((buf[0] & 0x80) == 0) return buf;
    byte[] tmp = new byte[buf.length + 1];
    System.arraycopy(buf, 0, tmp, 1, buf.length);
    Util.bzero(buf);
    return tmp;
  }

  private byte[] chop0(byte[] buf) {
    if (buf[0] != 0 || (buf[1] & 0x80) == 0)
      return buf;
    byte[] tmp = new byte[buf.length - 1];
    System.arraycopy(buf, 1, tmp, 0, tmp.length);
    Util.bzero(buf);
    return tmp;
  }
}
