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	/*
	* Copyright (c) 2012, 2019, 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.krb5.internal;

	import java.io.ByteArrayOutputStream;
	import java.io.IOException;
	import sun.security.krb5.*;
	import sun.security.krb5.internal.crypto.KeyUsage;
	import sun.security.krb5.internal.util.KerberosString;
	import sun.security.util.DerOutputStream;
	import sun.security.util.DerValue;

	/**
	* Implements the ASN.1 PA-FOR-USER type.
	*
	* <pre>{@code
	* padata-type ::= PA-FOR-USER
	* -- value 129
	* padata-value ::= EncryptedData
	* -- PA-FOR-USER-ENC
	* PA-FOR-USER-ENC ::= SEQUENCE {
	* userName[0] PrincipalName,
	* userRealm[1] Realm,
	* cksum[2] Checksum,
	* auth-package[3] KerberosString
	* }
	* }</pre>
	*
	* <p>
	* This definition reflects MS-SFU.
	*/

	public class PAForUserEnc {
	final public PrincipalName name;
	final private EncryptionKey key;
	final public static String AUTH_PACKAGE = "Kerberos";

	public PAForUserEnc(PrincipalName name, EncryptionKey key) {
	this.name = name;
	this.key = key;
	}

	/**
	* Constructs a PA-FOR-USER object from a DER encoding.
	* @param encoding the input object
	* @param key the key to verify the checksum inside encoding
	* @throws KrbException if the verification fails.
	* Note: this method is now only used by test KDC, therefore
	* the verification is ignored (at the moment).
	*/
	public PAForUserEnc(DerValue encoding, EncryptionKey key)
	throws Asn1Exception, KrbException, IOException {
	DerValue der = null;
	this.key = key;

	if (encoding.getTag() != DerValue.tag_Sequence) {
	throw new Asn1Exception(Krb5.ASN1_BAD_ID);
	}

	// Realm after name? Quite abnormal.
	PrincipalName tmpName = null;
	der = encoding.getData().getDerValue();
	if ((der.getTag() & 0x1F) == 0x00) {
	try {
	tmpName = new PrincipalName(der.getData().getDerValue(),
	new Realm("PLACEHOLDER"));
	} catch (RealmException re) {
	// Impossible
	}
	} else {
	throw new Asn1Exception(Krb5.ASN1_BAD_ID);
	}

	der = encoding.getData().getDerValue();
	if ((der.getTag() & 0x1F) == 0x01) {
	try {
	Realm realm = new Realm(der.getData().getDerValue());
	name = new PrincipalName(
	tmpName.getNameType(), tmpName.getNameStrings(), realm);
	} catch (RealmException re) {
	throw new IOException(re);
	}
	} else {
	throw new Asn1Exception(Krb5.ASN1_BAD_ID);
	}

	der = encoding.getData().getDerValue();
	if ((der.getTag() & 0x1F) == 0x02) {
	// Deal with the checksum
	} else {
	throw new Asn1Exception(Krb5.ASN1_BAD_ID);
	}

	der = encoding.getData().getDerValue();
	if ((der.getTag() & 0x1F) == 0x03) {
	String authPackage = new KerberosString(der.getData().getDerValue()).toString();
	if (!authPackage.equalsIgnoreCase(AUTH_PACKAGE)) {
	throw new IOException("Incorrect auth-package");
	}
	} else {
	throw new Asn1Exception(Krb5.ASN1_BAD_ID);
	}
	if (encoding.getData().available() > 0)
	throw new Asn1Exception(Krb5.ASN1_BAD_ID);
	}

	public byte[] asn1Encode() throws Asn1Exception, IOException {
	DerOutputStream bytes = new DerOutputStream();
	bytes.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)0x00), name.asn1Encode());
	bytes.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)0x01), name.getRealm().asn1Encode());

	try {
	// MS-SFU 2.2.1: use hmac-md5 checksum regardless of key type
	Checksum cks = new Checksum(
	Checksum.CKSUMTYPE_HMAC_MD5_ARCFOUR,
	getS4UByteArray(),
	key,
	KeyUsage.KU_PA_FOR_USER_ENC_CKSUM);
	bytes.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)0x02), cks.asn1Encode());
	} catch (KrbException ke) {
	throw new IOException(ke);
	}

	DerOutputStream temp = new DerOutputStream();
	temp.putDerValue(new KerberosString(AUTH_PACKAGE).toDerValue());
	bytes.write(DerValue.createTag(DerValue.TAG_CONTEXT, true, (byte)0x03), temp);

	temp = new DerOutputStream();
	temp.write(DerValue.tag_Sequence, bytes);
	return temp.toByteArray();
	}

	/**
	* Returns S4UByteArray, the block to calculate checksum inside a
	* PA-FOR-USER-ENC data structure. It includes:
	* 1. userName.name-type encoded as a 4-byte integer in little endian
	* byte order
	* 2. all string values in the sequence of strings contained in the
	* userName.name-string field
	* 3. the string value of the userRealm field
	* 4. the string value of auth-package field
	*/
	public byte[] getS4UByteArray() {
	try {
	ByteArrayOutputStream ba = new ByteArrayOutputStream();
	ba.write(new byte[4]);
	for (String s: name.getNameStrings()) {
	ba.write(s.getBytes("UTF-8"));
	}
	ba.write(name.getRealm().toString().getBytes("UTF-8"));
	ba.write(AUTH_PACKAGE.getBytes("UTF-8"));
	byte[] output = ba.toByteArray();
	int pnType = name.getNameType();
	output[0] = (byte)(pnType & 0xff);
	output[1] = (byte)((pnType>>8) & 0xff);
	output[2] = (byte)((pnType>>16) & 0xff);
	output[3] = (byte)((pnType>>24) & 0xff);
	return output;
	} catch (IOException ioe) {
	// not possible
	throw new AssertionError("Cannot write ByteArrayOutputStream", ioe);
	}
	}

	public PrincipalName getName() {
	return name;
	}

	public String toString() {
	return "PA-FOR-USER: " + name;
	}
	}

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