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	/*
	* Copyright (c) 2006, 2021, 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 jdk.internal.access.SharedSecrets;

	import java.io.IOException;
	import java.math.BigInteger;
	import java.security.*;
	import java.security.interfaces.*;
	import java.security.spec.*;
	import java.util.Arrays;

	public final class ECUtil {

	// Used by SunEC
	public static byte[] sArray(BigInteger s, ECParameterSpec params) {
	byte[] arr = s.toByteArray();
	ArrayUtil.reverse(arr);
	int byteLength = (params.getOrder().bitLength() + 7) / 8;
	byte[] arrayS = new byte[byteLength];
	int length = Math.min(byteLength, arr.length);
	System.arraycopy(arr, 0, arrayS, 0, length);
	return arrayS;
	}

	// Used by SunPKCS11 and SunJSSE.
	public static ECPoint decodePoint(byte[] data, EllipticCurve curve)
	throws IOException {
	if ((data.length == 0) \|\| (data[0] != 4)) {
	throw new IOException("Only uncompressed point format supported");
	}
	// Per ANSI X9.62, an encoded point is a 1 byte type followed by
	// ceiling(log base 2 field-size / 8) bytes of x and the same of y.
	int n = (data.length - 1) / 2;
	if (n != ((curve.getField().getFieldSize() + 7 ) >> 3)) {
	throw new IOException("Point does not match field size");
	}

	byte[] xb = Arrays.copyOfRange(data, 1, 1 + n);
	byte[] yb = Arrays.copyOfRange(data, n + 1, n + 1 + n);

	return new ECPoint(new BigInteger(1, xb), new BigInteger(1, yb));
	}

	// Used by SunPKCS11 and SunJSSE.
	public static byte[] encodePoint(ECPoint point, EllipticCurve curve) {
	// get field size in bytes (rounding up)
	int n = (curve.getField().getFieldSize() + 7) >> 3;
	byte[] xb = trimZeroes(point.getAffineX().toByteArray());
	byte[] yb = trimZeroes(point.getAffineY().toByteArray());
	if ((xb.length > n) \|\| (yb.length > n)) {
	throw new RuntimeException
	("Point coordinates do not match field size");
	}
	byte[] b = new byte[1 + (n << 1)];
	b[0] = 4; // uncompressed
	System.arraycopy(xb, 0, b, n - xb.length + 1, xb.length);
	System.arraycopy(yb, 0, b, b.length - yb.length, yb.length);
	return b;
	}

	public static byte[] trimZeroes(byte[] b) {
	int i = 0;
	while ((i < b.length - 1) && (b[i] == 0)) {
	i++;
	}
	if (i == 0) {
	return b;
	}

	return Arrays.copyOfRange(b, i, b.length);
	}

	private static KeyFactory getKeyFactory() {
	try {
	return KeyFactory.getInstance("EC", "SunEC");
	} catch (NoSuchAlgorithmException \| NoSuchProviderException e) {
	throw new RuntimeException(e);
	}
	}

	public static ECPublicKey decodeX509ECPublicKey(byte[] encoded)
	throws InvalidKeySpecException {
	KeyFactory keyFactory = getKeyFactory();
	X509EncodedKeySpec keySpec = new X509EncodedKeySpec(encoded);

	return (ECPublicKey)keyFactory.generatePublic(keySpec);
	}

	public static byte[] x509EncodeECPublicKey(ECPoint w,
	ECParameterSpec params) throws InvalidKeySpecException {
	KeyFactory keyFactory = getKeyFactory();
	ECPublicKeySpec keySpec = new ECPublicKeySpec(w, params);
	Key key = keyFactory.generatePublic(keySpec);

	return key.getEncoded();
	}

	public static ECPrivateKey decodePKCS8ECPrivateKey(byte[] encoded)
	throws InvalidKeySpecException {
	KeyFactory keyFactory = getKeyFactory();
	PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encoded);
	try {
	return (ECPrivateKey) keyFactory.generatePrivate(keySpec);
	} finally {
	SharedSecrets.getJavaSecuritySpecAccess().clearEncodedKeySpec(keySpec);
	}
	}

	public static ECPrivateKey generateECPrivateKey(BigInteger s,
	ECParameterSpec params) throws InvalidKeySpecException {
	KeyFactory keyFactory = getKeyFactory();
	ECPrivateKeySpec keySpec = new ECPrivateKeySpec(s, params);

	return (ECPrivateKey)keyFactory.generatePrivate(keySpec);
	}

	public static AlgorithmParameters getECParameters(Provider p) {
	try {
	if (p != null) {
	return AlgorithmParameters.getInstance("EC", p);
	}

	return AlgorithmParameters.getInstance("EC");
	} catch (NoSuchAlgorithmException nsae) {
	throw new RuntimeException(nsae);
	}
	}

	public static byte[] encodeECParameterSpec(Provider p,
	ECParameterSpec spec) {
	AlgorithmParameters parameters = getECParameters(p);

	try {
	parameters.init(spec);
	} catch (InvalidParameterSpecException ipse) {
	throw new RuntimeException("Not a known named curve: " + spec);
	}

	try {
	return parameters.getEncoded();
	} catch (IOException ioe) {
	// it is a bug if this should happen
	throw new RuntimeException(ioe);
	}
	}

	public static ECParameterSpec getECParameterSpec(Provider p,
	ECParameterSpec spec) {
	AlgorithmParameters parameters = getECParameters(p);

	try {
	parameters.init(spec);
	return parameters.getParameterSpec(ECParameterSpec.class);
	} catch (InvalidParameterSpecException ipse) {
	return null;
	}
	}

	public static ECParameterSpec getECParameterSpec(Provider p,
	byte[] params)
	throws IOException {
	AlgorithmParameters parameters = getECParameters(p);

	parameters.init(params);

	try {
	return parameters.getParameterSpec(ECParameterSpec.class);
	} catch (InvalidParameterSpecException ipse) {
	return null;
	}
	}

	public static ECParameterSpec getECParameterSpec(Provider p, String name) {
	AlgorithmParameters parameters = getECParameters(p);

	try {
	parameters.init(new ECGenParameterSpec(name));
	return parameters.getParameterSpec(ECParameterSpec.class);
	} catch (InvalidParameterSpecException ipse) {
	return null;
	}
	}

	public static ECParameterSpec getECParameterSpec(Provider p, int keySize) {
	AlgorithmParameters parameters = getECParameters(p);

	try {
	parameters.init(new ECKeySizeParameterSpec(keySize));
	return parameters.getParameterSpec(ECParameterSpec.class);
	} catch (InvalidParameterSpecException ipse) {
	return null;
	}

	}

	public static String getCurveName(Provider p, ECParameterSpec spec) {
	ECGenParameterSpec nameSpec;
	AlgorithmParameters parameters = getECParameters(p);

	try {
	parameters.init(spec);
	nameSpec = parameters.getParameterSpec(ECGenParameterSpec.class);
	} catch (InvalidParameterSpecException ipse) {
	return null;
	}

	if (nameSpec == null) {
	return null;
	}

	return nameSpec.getName();
	}

	public static boolean equals(ECParameterSpec spec1, ECParameterSpec spec2) {
	if (spec1 == spec2) {
	return true;
	}

	if (spec1 == null \|\| spec2 == null) {
	return false;
	}
	return (spec1.getCofactor() == spec2.getCofactor() &&
	spec1.getOrder().equals(spec2.getOrder()) &&
	spec1.getCurve().equals(spec2.getCurve()) &&
	spec1.getGenerator().equals(spec2.getGenerator()));
	}


	// Convert the concatenation R and S in into their DER encoding
	public static byte[] encodeSignature(byte[] signature) throws SignatureException {

	try {

	int n = signature.length >> 1;
	byte[] bytes = new byte[n];
	System.arraycopy(signature, 0, bytes, 0, n);
	BigInteger r = new BigInteger(1, bytes);
	System.arraycopy(signature, n, bytes, 0, n);
	BigInteger s = new BigInteger(1, bytes);

	DerOutputStream out = new DerOutputStream(signature.length + 10);
	out.putInteger(r);
	out.putInteger(s);
	DerValue result =
	new DerValue(DerValue.tag_Sequence, out.toByteArray());

	return result.toByteArray();

	} catch (Exception e) {
	throw new SignatureException("Could not encode signature", e);
	}
	}

	// Convert the DER encoding of R and S into a concatenation of R and S
	public static byte[] decodeSignature(byte[] sig) throws SignatureException {

	try {
	// Enforce strict DER checking for signatures
	DerInputStream in = new DerInputStream(sig, 0, sig.length, false);
	DerValue[] values = in.getSequence(2);

	// check number of components in the read sequence
	// and trailing data
	if ((values.length != 2) \|\| (in.available() != 0)) {
	throw new IOException("Invalid encoding for signature");
	}

	BigInteger r = values[0].getPositiveBigInteger();
	BigInteger s = values[1].getPositiveBigInteger();

	// trim leading zeroes
	byte[] rBytes = trimZeroes(r.toByteArray());
	byte[] sBytes = trimZeroes(s.toByteArray());
	int k = Math.max(rBytes.length, sBytes.length);
	// r and s each occupy half the array
	byte[] result = new byte[k << 1];
	System.arraycopy(rBytes, 0, result, k - rBytes.length,
	rBytes.length);
	System.arraycopy(sBytes, 0, result, result.length - sBytes.length,
	sBytes.length);
	return result;

	} catch (Exception e) {
	throw new SignatureException("Invalid encoding for signature", e);
	}
	}

	private ECUtil() {}
	}

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