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This is a collection of JAVA libraries that implement Unbound cryptographic classes for JAVA provider, PKCS11 wrapper, cryptoki, and advapi

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package com.unbound.provider;

import com.unbound.common.crypto.EC;

import javax.crypto.KeyAgreementSpi;
import javax.crypto.SecretKey;
import javax.crypto.ShortBufferException;
import javax.crypto.spec.SecretKeySpec;
import java.io.IOException;
import java.security.*;
import java.security.interfaces.ECPublicKey;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.ECPoint;

public class ECDHKeyAgreement extends KeyAgreementSpi
{
  UBECPrivateKey prvKey;
  ECPoint pub;

  @Override
  protected void engineInit(Key key, SecureRandom secureRandom) throws InvalidKeyException
  {
    if (key instanceof UBECPrivateKey == false) throw new InvalidKeyException("Key must be instance of UBECPrivateKey");
    prvKey = (UBECPrivateKey) key;
  }

  @Override
  protected void engineInit(Key key, AlgorithmParameterSpec algorithmParameterSpec, SecureRandom secureRandom) throws InvalidKeyException, InvalidAlgorithmParameterException
  {
    if (algorithmParameterSpec != null) throw new InvalidAlgorithmParameterException("Parameters not supported");
    engineInit(key, null);
  }

  @Override
  protected Key engineDoPhase(Key key, boolean lastPhase) throws InvalidKeyException, IllegalStateException
  {
    if (prvKey == null) throw new IllegalStateException("Not initialized");
    if (!lastPhase) throw new IllegalStateException("Only two party agreement supported, lastPhase must be true");
    if (pub != null) throw new IllegalStateException("Phase already executed");
    if (!(key instanceof ECPublicKey))
      throw new InvalidKeyException("Key must be a ECPublicKey");

    ECPublicKey pubKey = (ECPublicKey) key;
    EC.Curve curve = prvKey.getCurve();

    if (!pubKey.getParams().equals(curve.spec))
    {
      throw new InvalidKeyException("EC curve doesn't match");
    }

    pub = pubKey.getW();
    return null;
  }

  @Override
  protected byte[] engineGenerateSecret() throws IllegalStateException
  {
    if ((prvKey == null) || (pub == null)) throw new IllegalStateException("Not initialized correctly");
    try { return prvKey.ecdh(pub); }
    catch (IOException e) { throw new ProviderException(e); }
  }

  @Override
  protected int engineGenerateSecret(byte[] out, int outOffset) throws IllegalStateException, ShortBufferException
  {
    EC.Curve curve = prvKey.getCurve();
    int secretLen = curve.size;
    if (outOffset + secretLen > out.length)
      throw new ShortBufferException("Need " + secretLen + " bytes, only " + (out.length - outOffset) + " available");
    byte[] secret = engineGenerateSecret();
    System.arraycopy(secret, 0, out, outOffset, secret.length);
    return secret.length;
  }

  @Override
  protected SecretKey engineGenerateSecret(String algorithm) throws IllegalStateException, NoSuchAlgorithmException, InvalidKeyException
  {
    if (algorithm == null) throw new NoSuchAlgorithmException("Algorithm must not be null");
    if (!(algorithm.equals("TlsPremasterSecret")))
      throw new NoSuchAlgorithmException("Only supported for algorithm TlsPremasterSecret");
    return new SecretKeySpec(engineGenerateSecret(), "TlsPremasterSecret");
  }
}