/**
 * Get the key size of a public key.
 *
 * @param pubKey The public key
 * @return The key size, {@link #UNKNOWN_KEY_SIZE} if not known
 */
public static int getKeyLength(PublicKey pubKey)
{
	if (pubKey instanceof RSAKey)
	{
		return ((RSAKey) pubKey).getModulus().bitLength();
	}
	else if (pubKey instanceof DSAKey)
	{
		return ((DSAKey) pubKey).getParams().getP().bitLength();
	}
	else if (pubKey instanceof DHKey)
	{
		return ((DHKey) pubKey).getParams().getP().bitLength();
	}
	else if (pubKey instanceof ECKey)
	{
		// TODO: how to get key size from these?
		return UNKNOWN_KEY_SIZE;
	}

	LOG.warning("Don't know how to get key size from key " + pubKey);
	return UNKNOWN_KEY_SIZE;
}
 

/**
 * Get the key size of a public key.
 * 
 * @param pubKey The public key
 * @return The key size, {@link #UNKNOWN_KEY_SIZE} if not known
 */
public static int getKeyLength(PublicKey pubKey)
{
	if (pubKey instanceof RSAKey)
	{
		return ((RSAKey) pubKey).getModulus().bitLength();
	}
	else if (pubKey instanceof DSAKey)
	{
		return ((DSAKey) pubKey).getParams().getP().bitLength();
	}
	else if (pubKey instanceof DHKey)
	{
		return ((DHKey) pubKey).getParams().getP().bitLength();
	}
	else if (pubKey instanceof ECKey)
	{
		// TODO: how to get key size from these?
		return UNKNOWN_KEY_SIZE;
	}

	_logger.warn("Don't know how to get key size from key " + pubKey);
	return UNKNOWN_KEY_SIZE;
}
 

/**
 * 初始化密钥协商算法的乙方密钥对
 *
 * @param publicKey 甲方公钥的二进制形式
 * @return 乙方密钥对
 */
public Map<String, Key> initKey(byte[] publicKey) {
    PublicKey pubKey = this.toPublicKey(publicKey);
    KeyPairGenerator keyPairGenerator = getKeyPairGenerator();
    AlgorithmParameterSpec algorithmParameterSpec = null;
    if (pubKey instanceof DHKey) {
        algorithmParameterSpec = ((DHKey) pubKey).getParams();
    } else if (pubKey instanceof ECKey) {
        algorithmParameterSpec = ((ECKey) pubKey).getParams();
    } else {
        throw new CryptographyException(ExceptionInfo.NO_SUCH_ALGORITHM_EXCEPTION_INFO + getConfiguration().getKeyAlgorithm());
    }
    try {
        keyPairGenerator.initialize(algorithmParameterSpec);
    } catch (InvalidAlgorithmParameterException e) {
        throw new CryptographyException(ExceptionInfo.NO_SUCH_ALGORITHM_EXCEPTION_INFO + getConfiguration().getKeyAlgorithm(), e);
    }
    KeyPair keyPair = keyPairGenerator.generateKeyPair();
    Map<String, Key> keyMap = new HashMap<String, Key>();
    keyMap.put(PRIVATE_KEY, keyPair.getPrivate());
    keyMap.put(PUBLIC_KEY, keyPair.getPublic());
    return keyMap;
}
 

public int engineGetKeySize(Key key)
{
    if (key instanceof DHKey)
    {
        return ((DHKey)key).getParams().getP().bitLength();
    }
    else
    {
        throw new IllegalArgumentException("not a DH key");
    }
}
 

public int engineGetKeySize(Key key)
{
    if (key instanceof DHKey)
    {
        return ((DHKey)key).getParams().getP().bitLength();
    }
    else
    {
        throw new IllegalArgumentException("not a DH key");
    }
}
 

public int engineGetOutputSize(int inputLen)
{
    int len1, len2, len3;

    len1 = engine.getMac().getMacSize();

    if (key != null)
    {
        len2 = ((DHKey)key).getParams().getP().bitLength() / 8 + 1;
    }
    else
    {
        throw new IllegalStateException("cipher not initialised");
    }

    if (engine.getCipher() == null)
    {
        len3 = inputLen;
    }
    else if (state == Cipher.ENCRYPT_MODE || state == Cipher.WRAP_MODE)
    {
        len3 = engine.getCipher().getOutputSize(inputLen);
    }
    else if (state == Cipher.DECRYPT_MODE || state == Cipher.UNWRAP_MODE)
    {
        len3 = engine.getCipher().getOutputSize(inputLen - len1 - len2);
    }
    else
    {
        throw new IllegalStateException("cipher not initialised");
    }

    if (state == Cipher.ENCRYPT_MODE || state == Cipher.WRAP_MODE)
    {
        return buffer.size() + len1 + len2 + len3;
    }
    else if (state == Cipher.DECRYPT_MODE || state == Cipher.UNWRAP_MODE)
    {
        return buffer.size() - len1 - len2 + len3;
    }
    else
    {
        throw new IllegalStateException("IESCipher not initialised");
    }

}
 

public int engineGetOutputSize(int inputLen)
{
    int len1, len2, len3;

    len1 = engine.getMac().getMacSize();

    if (key != null)
    {
        len2 = ((DHKey)key).getParams().getP().bitLength() / 8 + 1;
    }
    else
    {
        throw new IllegalStateException("cipher not initialised");
    }

    if (engine.getCipher() == null)
    {
        len3 = inputLen;
    }
    else if (state == Cipher.ENCRYPT_MODE || state == Cipher.WRAP_MODE)
    {
        len3 = engine.getCipher().getOutputSize(inputLen);
    }
    else if (state == Cipher.DECRYPT_MODE || state == Cipher.UNWRAP_MODE)
    {
        len3 = engine.getCipher().getOutputSize(inputLen - len1 - len2);
    }
    else
    {
        throw new IllegalStateException("cipher not initialised");
    }

    if (state == Cipher.ENCRYPT_MODE || state == Cipher.WRAP_MODE)
    {
        return buffer.size() + len1 + len2 + len3;
    }
    else if (state == Cipher.DECRYPT_MODE || state == Cipher.UNWRAP_MODE)
    {
        return buffer.size() - len1 - len2 + len3;
    }
    else
    {
        throw new IllegalStateException("IESCipher not initialised");
    }

}