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	/*
	* Copyright (c) 2000, 2013, 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 javax.security.auth.kerberos;

	import java.util.Arrays;
	import javax.crypto.SecretKey;
	import javax.security.auth.Destroyable;
	import javax.security.auth.DestroyFailedException;

	/**
	* This class encapsulates a long term secret key for a Kerberos
	* principal.<p>
	*
	* All Kerberos JAAS login modules that obtain a principal's password and
	* generate the secret key from it should use this class.
	* Sometimes, such as when authenticating a server in
	* the absence of user-to-user authentication, the login module will store
	* an instance of this class in the private credential set of a
	* {@link javax.security.auth.Subject Subject} during the commit phase of the
	* authentication process.<p>
	*
	* A Kerberos service using a keytab to read secret keys should use
	* the {@link KeyTab} class, where latest keys can be read when needed.<p>
	*
	* It might be necessary for the application to be granted a
	* {@link javax.security.auth.PrivateCredentialPermission
	* PrivateCredentialPermission} if it needs to access the KerberosKey
	* instance from a Subject. This permission is not needed when the
	* application depends on the default JGSS Kerberos mechanism to access the
	* KerberosKey. In that case, however, the application will need an
	* appropriate
	* {@link javax.security.auth.kerberos.ServicePermission ServicePermission}.
	*
	* @author Mayank Upadhyay
	* @since 1.4
	*/
	public class KerberosKey implements SecretKey, Destroyable {

	private static final long serialVersionUID = -4625402278148246993L;

	/**
	* The principal that this secret key belongs to.
	*
	* @serial
	*/
	private KerberosPrincipal principal;

	/**
	* the version number of this secret key
	*
	* @serial
	*/
	private int versionNum;

	/**
	* {@code KeyImpl} is serialized by writing out the ASN1 Encoded bytes
	* of the encryption key.
	* The ASN1 encoding is defined in RFC4120 and as follows:
	* <pre>
	* EncryptionKey ::= SEQUENCE {
	* keytype [0] Int32 -- actually encryption type --,
	* keyvalue [1] OCTET STRING
	* }
	* </pre>
	*
	* @serial
	*/

	private KeyImpl key;
	private transient boolean destroyed = false;

	/**
	* Constructs a KerberosKey from the given bytes when the key type and
	* key version number are known. This can be used when reading the secret
	* key information from a Kerberos "keytab".
	*
	* @param principal the principal that this secret key belongs to
	* @param keyBytes the raw bytes for the secret key
	* @param keyType the key type for the secret key as defined by the
	* Kerberos protocol specification.
	* @param versionNum the version number of this secret key
	*/
	public KerberosKey(KerberosPrincipal principal,
	byte[] keyBytes,
	int keyType,
	int versionNum) {
	this.principal = principal;
	this.versionNum = versionNum;
	key = new KeyImpl(keyBytes, keyType);
	}

	/**
	* Constructs a KerberosKey from a principal's password.
	*
	* @param principal the principal that this password belongs to
	* @param password the password that should be used to compute the key
	* @param algorithm the name for the algorithm that this key will be
	* used for. This parameter may be null in which case the default
	* algorithm "DES" will be assumed.
	* @throws IllegalArgumentException if the name of the
	* algorithm passed is unsupported.
	*/
	public KerberosKey(KerberosPrincipal principal,
	char[] password,
	String algorithm) {

	this.principal = principal;
	// Pass principal in for salt
	key = new KeyImpl(principal, password, algorithm);
	}

	/**
	* Returns the principal that this key belongs to.
	*
	* @return the principal this key belongs to.
	*/
	public final KerberosPrincipal getPrincipal() {
	if (destroyed)
	throw new IllegalStateException("This key is no longer valid");
	return principal;
	}

	/**
	* Returns the key version number.
	*
	* @return the key version number.
	*/
	public final int getVersionNumber() {
	if (destroyed)
	throw new IllegalStateException("This key is no longer valid");
	return versionNum;
	}

	/**
	* Returns the key type for this long-term key.
	*
	* @return the key type.
	*/
	public final int getKeyType() {
	if (destroyed)
	throw new IllegalStateException("This key is no longer valid");
	return key.getKeyType();
	}

	/*
	* Methods from java.security.Key
	*/

	/**
	* Returns the standard algorithm name for this key. For
	* example, "DES" would indicate that this key is a DES key.
	* See Appendix A in the <a href=
	* "../../../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
	* Java Cryptography Architecture API Specification & Reference
	* </a>
	* for information about standard algorithm names.
	*
	* @return the name of the algorithm associated with this key.
	*/
	public final String getAlgorithm() {
	if (destroyed)
	throw new IllegalStateException("This key is no longer valid");
	return key.getAlgorithm();
	}

	/**
	* Returns the name of the encoding format for this secret key.
	*
	* @return the String "RAW"
	*/
	public final String getFormat() {
	if (destroyed)
	throw new IllegalStateException("This key is no longer valid");
	return key.getFormat();
	}

	/**
	* Returns the key material of this secret key.
	*
	* @return the key material
	*/
	public final byte[] getEncoded() {
	if (destroyed)
	throw new IllegalStateException("This key is no longer valid");
	return key.getEncoded();
	}

	/**
	* Destroys this key. A call to any of its other methods after this
	* will cause an IllegalStateException to be thrown.
	*
	* @throws DestroyFailedException if some error occurs while destorying
	* this key.
	*/
	public void destroy() throws DestroyFailedException {
	if (!destroyed) {
	key.destroy();
	principal = null;
	destroyed = true;
	}
	}


	/** Determines if this key has been destroyed.*/
	public boolean isDestroyed() {
	return destroyed;
	}

	public String toString() {
	if (destroyed) {
	return "Destroyed Principal";
	}
	return "Kerberos Principal " + principal.toString() +
	"Key Version " + versionNum +
	"key " + key.toString();
	}

	/**
	* Returns a hashcode for this KerberosKey.
	*
	* @return a hashCode() for the {@code KerberosKey}
	* @since 1.6
	*/
	public int hashCode() {
	int result = 17;
	if (isDestroyed()) {
	return result;
	}
	result = 37 * result + Arrays.hashCode(getEncoded());
	result = 37 * result + getKeyType();
	if (principal != null) {
	result = 37 * result + principal.hashCode();
	}
	return result * 37 + versionNum;
	}

	/**
	* Compares the specified Object with this KerberosKey for equality.
	* Returns true if the given object is also a
	* {@code KerberosKey} and the two
	* {@code KerberosKey} instances are equivalent.
	*
	* @param other the Object to compare to
	* @return true if the specified object is equal to this KerberosKey,
	* false otherwise. NOTE: Returns false if either of the KerberosKey
	* objects has been destroyed.
	* @since 1.6
	*/
	public boolean equals(Object other) {

	if (other == this)
	return true;

	if (! (other instanceof KerberosKey)) {
	return false;
	}

	KerberosKey otherKey = ((KerberosKey) other);
	if (isDestroyed() \|\| otherKey.isDestroyed()) {
	return false;
	}

	if (versionNum != otherKey.getVersionNumber() \|\|
	getKeyType() != otherKey.getKeyType() \|\|
	!Arrays.equals(getEncoded(), otherKey.getEncoded())) {
	return false;
	}

	if (principal == null) {
	if (otherKey.getPrincipal() != null) {
	return false;
	}
	} else {
	if (!principal.equals(otherKey.getPrincipal())) {
	return false;
	}
	}

	return true;
	}
	}

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