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	/*
	* Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.security.util;

	import java.security.AlgorithmParameters;
	import java.security.Key;
	import java.security.PrivilegedAction;
	import java.security.AccessController;
	import java.security.InvalidKeyException;
	import java.security.interfaces.ECKey;
	import java.security.interfaces.RSAKey;
	import java.security.interfaces.DSAKey;
	import java.security.interfaces.DSAParams;
	import java.security.SecureRandom;
	import java.security.spec.KeySpec;
	import java.security.spec.ECParameterSpec;
	import java.security.spec.InvalidParameterSpecException;
	import javax.crypto.SecretKey;
	import javax.crypto.interfaces.DHKey;
	import javax.crypto.interfaces.DHPublicKey;
	import javax.crypto.spec.DHParameterSpec;
	import javax.crypto.spec.DHPublicKeySpec;
	import java.math.BigInteger;

	import sun.security.jca.JCAUtil;

	/**
	* A utility class to get key length, valiate keys, etc.
	*/
	public final class KeyUtil {

	/**
	* Returns the key size of the given key object in bits.
	*
	* @param key the key object, cannot be null
	* @return the key size of the given key object in bits, or -1 if the
	* key size is not accessible
	*/
	public static final int getKeySize(Key key) {
	int size = -1;

	if (key instanceof Length) {
	try {
	Length ruler = (Length)key;
	size = ruler.length();
	} catch (UnsupportedOperationException usoe) {
	// ignore the exception
	}

	if (size >= 0) {
	return size;
	}
	}

	// try to parse the length from key specification
	if (key instanceof SecretKey) {
	SecretKey sk = (SecretKey)key;
	String format = sk.getFormat();
	if ("RAW".equals(format) && sk.getEncoded() != null) {
	size = (sk.getEncoded().length * 8);
	} // Otherwise, it may be a unextractable key of PKCS#11, or
	// a key we are not able to handle.
	} else if (key instanceof RSAKey) {
	RSAKey pubk = (RSAKey)key;
	size = pubk.getModulus().bitLength();
	} else if (key instanceof ECKey) {
	ECKey pubk = (ECKey)key;
	size = pubk.getParams().getOrder().bitLength();
	} else if (key instanceof DSAKey) {
	DSAKey pubk = (DSAKey)key;
	DSAParams params = pubk.getParams(); // params can be null
	size = (params != null) ? params.getP().bitLength() : -1;
	} else if (key instanceof DHKey) {
	DHKey pubk = (DHKey)key;
	size = pubk.getParams().getP().bitLength();
	} // Otherwise, it may be a unextractable key of PKCS#11, or
	// a key we are not able to handle.

	return size;
	}

	/**
	* Returns the key size of the given cryptographic parameters in bits.
	*
	* @param parameters the cryptographic parameters, cannot be null
	* @return the key size of the given cryptographic parameters in bits,
	* or -1 if the key size is not accessible
	*/
	public static final int getKeySize(AlgorithmParameters parameters) {

	String algorithm = parameters.getAlgorithm();
	switch (algorithm) {
	case "EC":
	try {
	ECKeySizeParameterSpec ps = parameters.getParameterSpec(
	ECKeySizeParameterSpec.class);
	if (ps != null) {
	return ps.getKeySize();
	}
	} catch (InvalidParameterSpecException ipse) {
	// ignore
	}

	try {
	ECParameterSpec ps = parameters.getParameterSpec(
	ECParameterSpec.class);
	if (ps != null) {
	return ps.getOrder().bitLength();
	}
	} catch (InvalidParameterSpecException ipse) {
	// ignore
	}

	// Note: the ECGenParameterSpec case should be covered by the
	// ECParameterSpec case above.
	// See ECUtil.getECParameterSpec(Provider, String).

	break;
	case "DiffieHellman":
	try {
	DHParameterSpec ps = parameters.getParameterSpec(
	DHParameterSpec.class);
	if (ps != null) {
	return ps.getP().bitLength();
	}
	} catch (InvalidParameterSpecException ipse) {
	// ignore
	}
	break;

	// May support more AlgorithmParameters algorithms in the future.
	}

	return -1;
	}

	/**
	* Returns whether the key is valid or not.
	* <P>
	* Note that this method is only apply to DHPublicKey at present.
	*
	* @param key the key object, cannot be null
	*
	* @throws NullPointerException if {@code key} is null
	* @throws InvalidKeyException if {@code key} is invalid
	*/
	public static final void validate(Key key)
	throws InvalidKeyException {
	if (key == null) {
	throw new NullPointerException(
	"The key to be validated cannot be null");
	}

	if (key instanceof DHPublicKey) {
	validateDHPublicKey((DHPublicKey)key);
	}
	}


	/**
	* Returns whether the key spec is valid or not.
	* <P>
	* Note that this method is only apply to DHPublicKeySpec at present.
	*
	* @param keySpec
	* the key spec object, cannot be null
	*
	* @throws NullPointerException if {@code keySpec} is null
	* @throws InvalidKeyException if {@code keySpec} is invalid
	*/
	public static final void validate(KeySpec keySpec)
	throws InvalidKeyException {
	if (keySpec == null) {
	throw new NullPointerException(
	"The key spec to be validated cannot be null");
	}

	if (keySpec instanceof DHPublicKeySpec) {
	validateDHPublicKey((DHPublicKeySpec)keySpec);
	}
	}

	/**
	* Returns whether the specified provider is Oracle provider or not.
	*
	* @param providerName
	* the provider name
	* @return true if, and only if, the provider of the specified
	* {@code providerName} is Oracle provider
	*/
	public static final boolean isOracleJCEProvider(String providerName) {
	return providerName != null &&
	(providerName.equals("SunJCE") \|\|
	providerName.equals("SunMSCAPI") \|\|
	providerName.equals("OracleUcrypto") \|\|
	providerName.startsWith("SunPKCS11"));
	}

	/**
	* Check the format of TLS PreMasterSecret.
	* <P>
	* To avoid vulnerabilities described by section 7.4.7.1, RFC 5246,
	* treating incorrectly formatted message blocks and/or mismatched
	* version numbers in a manner indistinguishable from correctly
	* formatted RSA blocks.
	*
	* RFC 5246 describes the approach as:
	* <pre>{@literal
	*
	* 1. Generate a string R of 48 random bytes
	*
	* 2. Decrypt the message to recover the plaintext M
	*
	* 3. If the PKCS#1 padding is not correct, or the length of message
	* M is not exactly 48 bytes:
	* pre_master_secret = R
	* else If ClientHello.client_version <= TLS 1.0, and version
	* number check is explicitly disabled:
	* premaster secret = M
	* else If M[0..1] != ClientHello.client_version:
	* premaster secret = R
	* else:
	* premaster secret = M
	*
	* Note that #2 should have completed before the call to this method.
	* }</pre>
	*
	* @param clientVersion the version of the TLS protocol by which the
	* client wishes to communicate during this session
	* @param serverVersion the negotiated version of the TLS protocol which
	* contains the lower of that suggested by the client in the client
	* hello and the highest supported by the server.
	* @param encoded the encoded key in its "RAW" encoding format
	* @param isFailOver whether or not the previous decryption of the
	* encrypted PreMasterSecret message run into problem
	* @return the polished PreMasterSecret key in its "RAW" encoding format
	*/
	public static byte[] checkTlsPreMasterSecretKey(
	int clientVersion, int serverVersion, SecureRandom random,
	byte[] encoded, boolean isFailOver) {

	if (random == null) {
	random = JCAUtil.getSecureRandom();
	}
	byte[] replacer = new byte[48];
	random.nextBytes(replacer);

	if (!isFailOver && (encoded != null)) {
	// check the length
	if (encoded.length != 48) {
	// private, don't need to clone the byte array.
	return replacer;
	}

	int encodedVersion =
	((encoded[0] & 0xFF) << 8) \| (encoded[1] & 0xFF);
	if (clientVersion != encodedVersion) {
	if (clientVersion > 0x0301 \|\| // 0x0301: TLSv1
	serverVersion != encodedVersion) {
	encoded = replacer;
	} // Otherwise, For compatibility, we maintain the behavior
	// that the version in pre_master_secret can be the
	// negotiated version for TLS v1.0 and SSL v3.0.
	}

	// private, don't need to clone the byte array.
	return encoded;
	}

	// private, don't need to clone the byte array.
	return replacer;
	}

	/**
	* Returns whether the Diffie-Hellman public key is valid or not.
	*
	* Per RFC 2631 and NIST SP800-56A, the following algorithm is used to
	* validate Diffie-Hellman public keys:
	* 1. Verify that y lies within the interval [2,p-1]. If it does not,
	* the key is invalid.
	* 2. Compute y^q mod p. If the result == 1, the key is valid.
	* Otherwise the key is invalid.
	*/
	private static void validateDHPublicKey(DHPublicKey publicKey)
	throws InvalidKeyException {
	DHParameterSpec paramSpec = publicKey.getParams();

	BigInteger p = paramSpec.getP();
	BigInteger g = paramSpec.getG();
	BigInteger y = publicKey.getY();

	validateDHPublicKey(p, g, y);
	}

	private static void validateDHPublicKey(DHPublicKeySpec publicKeySpec)
	throws InvalidKeyException {
	validateDHPublicKey(publicKeySpec.getP(),
	publicKeySpec.getG(), publicKeySpec.getY());
	}

	private static void validateDHPublicKey(BigInteger p,
	BigInteger g, BigInteger y) throws InvalidKeyException {

	// For better interoperability, the interval is limited to [2, p-2].
	BigInteger leftOpen = BigInteger.ONE;
	BigInteger rightOpen = p.subtract(BigInteger.ONE);
	if (y.compareTo(leftOpen) <= 0) {
	throw new InvalidKeyException(
	"Diffie-Hellman public key is too small");
	}
	if (y.compareTo(rightOpen) >= 0) {
	throw new InvalidKeyException(
	"Diffie-Hellman public key is too large");
	}

	// y^q mod p == 1?
	// Unable to perform this check as q is unknown in this circumstance.

	// p is expected to be prime. However, it is too expensive to check
	// that p is prime. Instead, in order to mitigate the impact of
	// non-prime values, we check that y is not a factor of p.
	BigInteger r = p.remainder(y);
	if (r.equals(BigInteger.ZERO)) {
	throw new InvalidKeyException("Invalid Diffie-Hellman parameters");
	}
	}

	/**
	* Trim leading (most significant) zeroes from the result.
	*
	* @throws NullPointerException if {@code b} is null
	*/
	public static byte[] trimZeroes(byte[] b) {
	int i = 0;
	while ((i < b.length - 1) && (b[i] == 0)) {
	i++;
	}
	if (i == 0) {
	return b;
	}
	byte[] t = new byte[b.length - i];
	System.arraycopy(b, i, t, 0, t.length);
	return t;
	}

	}

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