/*
* Copyright (c) 2000, 2015, 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.DestroyFailedException;
/**
* This class encapsulates a long term secret key for a Kerberos
* principal.<p>
*
* A {@code KerberosKey} object includes an EncryptionKey, a
* {@link KerberosPrincipal} as its owner, and the version number
* of the key.<p>
*
* An EncryptionKey is defined in Section 4.2.9 of the Kerberos Protocol
* Specification (<a href=http://www.ietf.org/rfc/rfc4120.txt>RFC 4120</a>) as:
* <pre>
* EncryptionKey ::= SEQUENCE {
* keytype [0] Int32 -- actually encryption type --,
* keyvalue [1] OCTET STRING
* }
* </pre>
* The key material of a {@code KerberosKey} is defined as the value
* of the {@code keyValue} above.<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 {@code KerberosKey}
* instance from a Subject. This permission is not needed when the
* application depends on the default JGSS Kerberos mechanism to access the
* {@code KerberosKey}. In that case, however, the application will need an
* appropriate
* {@link javax.security.auth.kerberos.ServicePermission ServicePermission}.<p>
*
* When creating a {@code KerberosKey} using the
* {@link #KerberosKey(KerberosPrincipal, char[], String)} constructor,
* an implementation may accept non-IANA algorithm names (For example,
* "ArcFourMac" for "rc4-hmac"), but the {@link #getAlgorithm} method
* must always return the IANA algorithm name.
*
* @implNote Old algorithm names used before JDK 9 are supported in the
* {@link #KerberosKey(KerberosPrincipal, char[], String)} constructor in this
* implementation for compatibility reasons, which are "DES" (and null) for
* "des-cbc-md5", "DESede" for "des3-cbc-sha1-kd", "ArcFourHmac" for "rc4-hmac",
* "AES128" for "aes128-cts-hmac-sha1-96", and "AES256" for
* "aes256-cts-hmac-sha1-96".
*
* @author Mayank Upadhyay
* @since 1.4
*/
public class KerberosKey implements SecretKey {
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 final int versionNum;
/**
* {@code KeyImpl} is serialized by writing out the ASN.1 encoded bytes
* of the encryption key.
*
* @serial
*/
private KeyImpl key;
private transient boolean destroyed = false;
/**
* Constructs a {@code 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 key material 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 {@code KerberosKey} from a principal's password using the
* specified algorithm name. The algorithm name (case insensitive) should
* be provided as the encryption type string defined on the IANA
* <a href="https://www.iana.org/assignments/kerberos-parameters/kerberos-parameters.xhtml#kerberos-parameters-1">Kerberos Encryption Type Numbers</a>
* page. The version number of the key generated will be 0.
*
* @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
* @throws IllegalArgumentException if the name of the
* algorithm passed is unsupported.
*/
public KerberosKey(KerberosPrincipal principal,
char[] password,
String algorithm) {
this.principal = principal;
this.versionNum = 0;
// 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.
* @throws IllegalStateException if the key is destroyed
*/
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.
* @throws IllegalStateException if the key is destroyed
*/
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.
* @throws IllegalStateException if the key is destroyed
*/
public final int getKeyType() {
// KeyImpl already checked if destroyed
return key.getKeyType();
}
/*
* Methods from java.security.Key
*/
/**
* Returns the standard algorithm name for this key. The algorithm names
* are the encryption type string defined on the IANA
* <a href="https://www.iana.org/assignments/kerberos-parameters/kerberos-parameters.xhtml#kerberos-parameters-1">Kerberos Encryption Type Numbers</a>
* page.
* <p>
* This method can return the following value not defined on the IANA page:
* <ol>
* <li>none: for etype equal to 0</li>
* <li>unknown: for etype greater than 0 but unsupported by
* the implementation</li>
* <li>private: for etype smaller than 0</li>
* </ol>
*
* @return the name of the algorithm associated with this key.
* @throws IllegalStateException if the key is destroyed
*/
public final String getAlgorithm() {
// KeyImpl already checked if destroyed
return key.getAlgorithm();
}
/**
* Returns the name of the encoding format for this secret key.
*
* @return the String "RAW"
* @throws IllegalStateException if the key is destroyed
*/
public final String getFormat() {
// KeyImpl already checked if destroyed
return key.getFormat();
}
/**
* Returns the key material of this secret key.
*
* @return the key material
* @throws IllegalStateException if the key is destroyed
*/
public final byte[] getEncoded() {
// KeyImpl already checked if destroyed
return key.getEncoded();
}
/**
* Destroys this key by clearing out the key material of this secret key.
*
* @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;
}
/**
* Returns an informative textual representation of this {@code KerberosKey}.
*
* @return an informative textual representation of this {@code KerberosKey}.
*/
public String toString() {
if (destroyed) {
return "Destroyed KerberosKey";
}
return "Kerberos Principal " + principal +
"Key Version " + versionNum +
"key " + key.toString();
}
/**
* Returns a hash code for this {@code KerberosKey}.
*
* @return a hash code for this {@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 {@code KerberosKey} for
* equality. Returns true if the given object is also a
* {@code KerberosKey} and the two
* {@code KerberosKey} instances are equivalent.
* A destroyed {@code KerberosKey} object is only equal to itself.
*
* @param other the object to compare to
* @return true if the specified object is equal to this {@code KerberosKey},
* false otherwise.
* @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;
}
}