RFC 2853
Generic Security Service API Version 2 : Java Bindings
6.5. public class MessageProp
This is a utility class used within the per-message GSSContext methods to convey per-message properties. When used with the GSSContext interface's wrap and getMIC methods, an instance of this class is used to indicate the desired QOP and to request if confidentiality services are to be applied to caller supplied data (wrap only). To request default QOP, the value of 0 should be used for QOP. When used with the unwrap and verifyMIC methods of the GSSContext interface, an instance of this class will be used to indicate the applied QOP and confidentiality services over the supplied message. In the case of verifyMIC, the confidentiality state will always be "false". Upon return from these methods, this object will also contain any supplementary status values applicable to the processed token. The supplementary status values can indicate old tokens, out of sequence tokens, gap tokens or duplicate tokens.6.5.1. Constructors
public MessageProp(boolean privState) Constructor which sets QOP to 0 indicating that the default QOP is requested. Parameters: privState The desired privacy state. "true" for privacy and "false" for integrity only. public MessageProp(int qop, boolean privState) Constructor which sets the values for the qop and privacy state. Parameters: qop The desired QOP. Use 0 to request a default QOP. privState The desired privacy state. "true" for privacy and "false" for integrity only.
6.5.2. getQOP
public int getQOP() Retrieves the QOP value.6.5.3. getPrivacy
public boolean getPrivacy() Retrieves the privacy state.6.5.4. getMinorStatus
public int getMinorStatus() Retrieves the minor status that the underlying mechanism might have set.6.5.5. getMinorString
public String getMinorString() Returns a string explaining the mechanism specific error code. null will be returned when no mechanism error code has been set.6.5.6. setQOP
public void setQOP(int qopVal) Sets the QOP value. Parameters: qopVal The QOP value to be set. Use 0 to request a default QOP value.6.5.7. setPrivacy
public void setPrivacy(boolean privState) Sets the privacy state. Parameters: privState The privacy state to set.
6.5.8. isDuplicateToken
public boolean isDuplicateToken() Returns "true" if this is a duplicate of an earlier token.6.5.9. isOldToken
public boolean isOldToken() Returns "true" if the token's validity period has expired.6.5.10. isUnseqToken
public boolean isUnseqToken() Returns "true" if a later token has already been processed.6.5.11. isGapToken
public boolean isGapToken() Returns "true" if an expected per-message token was not received.6.5.12. setSupplementaryStates
public void setSupplementaryStates(boolean duplicate, boolean old, boolean unseq, boolean gap, int minorStatus, String minorString) This method sets the state for the supplementary information flags and the minor status in MessageProp. It is not used by the application but by the GSS implementation to return this information to the caller of a per-message context method. Parameters: duplicate true if the token was a duplicate of an earlier token, false otherwise old true if the token's validity period has expired, false otherwise unseq true if a later token has already been processed, false otherwise gap true if one or more predecessor tokens have not yet been successfully processed, false otherwise
minorStatus the integer minor status code that the underlying
mechanism wants to set
minorString the textual representation of the minorStatus
value
6.6. public class ChannelBinding
The GSS-API accommodates the concept of caller-provided channel
binding information. Channel bindings are used to strengthen the
quality with which peer entity authentication is provided during
context establishment. They enable the GSS-API callers to bind the
establishment of the security context to relevant characteristics
like addresses or to application specific data.
The caller initiating the security context must determine the
appropriate channel binding values to set in the GSSContext object.
The acceptor must provide an identical binding in order to validate
that received tokens possess correct channel-related characteristics.
Use of channel bindings is optional in GSS-API. Since channel-
binding information may be transmitted in context establishment
tokens, applications should therefore not use confidential data as
channel-binding components.
6.6.1. Constructors
public ChannelBinding(InetAddress initAddr, InetAddress acceptAddr,
byte[] appData)
Create a ChannelBinding object with user supplied address information
and data. "null" values can be used for any fields which the
application does not want to specify.
Parameters:
initAddr The address of the context initiator. "null" value
can be supplied to indicate that the application does
not want to set this value.
acceptAddrThe address of the context acceptor. "null" value can
be supplied to indicate that the application does not
want to set this value.
appData Application supplied data to be used as part of the
channel bindings. "null" value can be supplied to
indicate that the application does not want to set
this value.
public ChannelBinding(byte[] appData)
Creates a ChannelBinding object without any addressing information.
Parameters:
appData Application supplied data to be used as part of the
channel bindings.
6.6.2. getInitiatorAddress
public InetAddress getInitiatorAddress()
Returns the initiator's address for this channel binding. "null" is
returned if the address has not been set.
6.6.3. getAcceptorAddress
public InetAddress getAcceptorAddress()
Returns the acceptor's address for this channel binding. "null" is
returned if the address has not been set.
6.6.4. getApplicationData
public byte[] getApplicationData()
Returns application data being used as part of the ChannelBinding.
"null" is returned if no application data has been specified for the
channel binding.
6.6.5. equals
public boolean equals(Object obj)
Returns "true" if two channel bindings match. (Note that the Java
language specification requires that two objects that are equal
according to the equals(Object) method must return the same integer
result when the hashCode() method is called on them.)
Parameters:
obj Another channel binding to compare with.
6.7. public class Oid
This class represents Universal Object Identifiers (Oids) and their associated operations. Oids are hierarchically globally-interpretable identifiers used within the GSS-API framework to identify mechanisms and name formats. The structure and encoding of Oids is defined in ISOIEC-8824 and ISOIEC-8825. For example the Oid representation of Kerberos V5 mechanism is "1.2.840.113554.1.2.2" The GSSName name class contains public static Oid objects representing the standard name types defined in GSS-API.6.7.1. Constructors
public Oid(String strOid) throws GSSException Creates an Oid object from a string representation of its integer components (e.g. "1.2.840.113554.1.2.2"). Parameters: strOid The string representation for the oid. public Oid(InputStream derOid) throws GSSException Creates an Oid object from its DER encoding. This refers to the full encoding including tag and length. The structure and encoding of Oids is defined in ISOIEC-8824 and ISOIEC-8825. This method is identical in functionality to its byte array counterpart. Parameters: derOid Stream containing the DER encoded oid. public Oid(byte[] DEROid) throws GSSException Creates an Oid object from its DER encoding. This refers to the full encoding including tag and length. The structure and encoding of Oids is defined in ISOIEC-8824 and ISOIEC-8825. This method is identical in functionality to its byte array counterpart. Parameters: derOid Byte array storing a DER encoded oid.
6.7.2. toString
public String toString() Returns a string representation of the oid's integer components in dot separated notation (e.g. "1.2.840.113554.1.2.2").6.7.3. equals
public boolean equals(Object Obj) Returns "true" if the two Oid objects represent the same oid value. (Note that the Java language specification requires that two objects that are equal according to the equals(Object) method must return the same integer result when the hashCode() method is called on them.) Parameters: obj Another Oid object to compare with.6.7.4. getDER
public byte[] getDER() Returns the full ASN.1 DER encoding for this oid object, which includes the tag and length.6.7.5. containedIn
public boolean containedIn(Oid[] oids) A utility method to test if an Oid object is contained within the supplied Oid object array. Parameters: oids An array of oids to search.6.8. public class GSSException extends Exception
This exception is thrown whenever a fatal GSS-API error occurs including mechanism specific errors. It may contain both, the major and minor, GSS-API status codes. The mechanism implementers are responsible for setting appropriate minor status codes when throwing this exception. Aside from delivering the numeric error code(s) to the caller, this class performs the mapping from their numeric values to textual representations. All Java GSS-API methods are declared throwing this exception.
All implementations are encouraged to use the Java internationalization techniques to provide local translations of the message strings.6.8.1. Static Constants
All valid major GSS-API error code values are declared as constants in this class. public static final int BAD_BINDINGS Channel bindings mismatch error. public static final int BAD_MECH Unsupported mechanism requested error. public static final int BAD_NAME Invalid name provided error. public static final int BAD_NAMETYPE Name of unsupported type provided error. public static final int BAD_STATUS Invalid status code error - this is the default status value. public static final int BAD_MIC Token had invalid integrity check error. public static final int CONTEXT_EXPIRED Specified security context expired error. public static final int CREDENTIALS_EXPIRED Expired credentials detected error.
public static final int DEFECTIVE_CREDENTIAL Defective credential error. public static final int DEFECTIVE_TOKEN Defective token error. public static final int FAILURE General failure, unspecified at GSS-API level. public static final int NO_CONTEXT Invalid security context error. public static final int NO_CRED Invalid credentials error. public static final int BAD_QOP Unsupported QOP value error. public static final int UNAUTHORIZED Operation unauthorized error. public static final int UNAVAILABLE Operation unavailable error. public static final int DUPLICATE_ELEMENT Duplicate credential element requested error. public static final int NAME_NOT_MN Name contains multi-mechanism elements error.
public static final int DUPLICATE_TOKEN The token was a duplicate of an earlier token. This is a fatal error code that may occur during context establishment. It is not used to indicate supplementary status values. The MessageProp object is used for that purpose. public static final int OLD_TOKEN The token's validity period has expired. This is a fatal error code that may occur during context establishment. It is not used to indicate supplementary status values. The MessageProp object is used for that purpose. public static final int UNSEQ_TOKEN A later token has already been processed. This is a fatal error code that may occur during context establishment. It is not used to indicate supplementary status values. The MessageProp object is used for that purpose. public static final int GAP_TOKEN An expected per-message token was not received. This is a fatal error code that may occur during context establishment. It is not used to indicate supplementary status values. The MessageProp object is used for that purpose.6.8.2. Constructors
public GSSException(int majorCode) Creates a GSSException object with a specified major code. Parameters: majorCode The GSS error code causing this exception to be thrown. public GSSException(int majorCode, int minorCode, String minorString) Creates a GSSException object with the specified major code, minor code, and minor code textual explanation. This constructor is to be used when the exception is originating from the security mechanism. It allows to specify the GSS code and the mechanism code.
Parameters:
majorCode The GSS error code causing this exception to be
thrown.
minorCode The mechanism error code causing this exception
to be thrown.
minorString The textual explanation of the mechanism error
code.
6.8.3. getMajor
public int getMajor()
Returns the major code representing the GSS error code that caused
this exception to be thrown.
6.8.4. getMinor
public int getMinor()
Returns the mechanism error code that caused this exception. The
minor code is set by the underlying mechanism. Value of 0 indicates
that mechanism error code is not set.
6.8.5. getMajorString
public String getMajorString()
Returns a string explaining the GSS major error code causing this
exception to be thrown.
6.8.6. getMinorString
public String getMinorString()
Returns a string explaining the mechanism specific error code. null
will be returned when no mechanism error code has been set.
6.8.7. setMinor
public void setMinor(int minorCode, String message)
Used internally by the GSS-API implementation and the underlying
mechanisms to set the minor code and its textual representation.
Parameters:
minorCode The mechanism specific error code.
message A textual explanation of the mechanism error code.
6.8.8. toString
public String toString()
Returns a textual representation of both the major and minor status
codes.
6.8.9. getMessage
public String getMessage()
Returns a detailed message of this exception. Overrides
Throwable.getMessage. It is customary in Java to use this method to
obtain exception information.
7. Sample Applications
7.1. Simple GSS Context Initiator
import org.ietf.jgss.*;
/**
* This is a partial sketch for a simple client program that acts
* as a GSS context initiator. It illustrates how to use the Java
* bindings for the GSS-API specified in
* Generic Security Service API Version 2 : Java bindings
*
*
* This code sketch assumes the existence of a GSS-API
* implementation that supports the mechanism that it will need and
* is present as a library package (org.ietf.jgss) either as part of
* the standard JRE or in the CLASSPATH the application specifies.
*/
public class SimpleClient {
private String serviceName; // name of peer (ie. server)
private GSSCredential clientCred = null;
private GSSContext context = null;
private Oid mech; // underlying mechanism to use
private GSSManager mgr = GSSManager.getInstance();
...
...
private void clientActions() {
initializeGSS();
establishContext();
doCommunication();
}
/**
* Acquire credentials for the client.
*/
private void initializeGSS() {
try {
clientCred = mgr.createCredential(null /*default princ*/,
GSSCredential.INDEFINITE_LIFETIME /* max lifetime */,
mech /* mechanism to use */,
GSSCredential.INITIATE_ONLY /* init context */);
print("GSSCredential created for " +
cred.getName().toString());
print("Credential lifetime (sec)=" +
cred.getRemainingLifetime());
} catch (GSSException e) {
print("GSS-API error in credential acquisition: "
+ e.getMessage());
...
...
}
...
...
}
/**
* Does the security context establishment with the
* server.
*/
private void establishContext() {
byte[] inToken = new byte[0];
byte[] outToken = null;
try {
GSSName peer = mgr.createName(serviceName,
GSSName.NT_HOSTBASED_SERVICE);
context = mgr.createContext(peer, mech, gssCred,
GSSContext.INDEFINITE_LIFETIME/*lifetime*/);
// Will need to support confidentiality
context.requestConf(true);
while (!context.isEstablished()) {
outToken = context.initSecContext(inToken, 0,
inToken.length);
if (outToken != null)
writeGSSToken(outToken);
if (!context.isEstablished())
inToken = readGSSToken();
}
GSSName peer = context.getSrcName();
print("Security context established with " + peer +
" using underlying mechanism " + mech.toString());
} catch (GSSException e) {
print("GSS-API error during context establishment: "
+ e.getMessage());
...
...
}
...
...
}
/**
* Sends some data to the server and reads back the
* response.
*/
private void doCommunication() {
byte[] inToken = null;
byte[] outToken = null;
byte[] buffer;
// Container for multiple input-output arguments to and
// from the per-message routines (e.g., wrap/unwrap).
MessageProp messgInfo = new MessageProp();
try {
/*
* Now send some bytes to the server to be
* processed. They will be integrity protected but
* not encrypted for privacy.
*/
buffer = readFromFile();
// Set privacy to false and use the default QOP
messgInfo.setPrivacy(false);
outToken = context.wrap(buffer, 0, buffer.length,
messgInfo);
writeGSSToken(outToken);
/*
* Now read the response from the server.
*/
inToken = readGSSToken();
buffer = context.unwrap(inToken, 0, inToken.length,
messgInfo);
// All ok if no exception was thrown!
GSSName peer = context.getSrcName();
print("Message from " + peer.toString()
+ " arrived.");
print("Was it encrypted? " +
messgInfo.getPrivacy());
print("Duplicate Token? " +
messgInfo.isDuplicateToken());
print("Old Token? " +
messgInfo.isOldToken());
print("Unsequenced Token? " +
messgInfo.isUnseqToken());
print("Gap Token? " +
messgInfo.isGapToken());
...
...
} catch (GSSException e) {
print("GSS-API error in per-message calls: "
+ e.getMessage());
...
...
}
...
...
} // end of doCommunication method
...
...
} // end of class SimpleClient
7.2. Simple GSS Context Acceptor
import org.ietf.jgss.*;
/**
* This is a partial sketch for a simple server program that acts
* as a GSS context acceptor. It illustrates how to use the Java
* bindings for the GSS-API specified in
* Generic Security Service API Version 2 : Java bindings
*
* This code sketch assumes the existence of a GSS-API
* implementation that supports the mechanisms that it will need and
* is present as a library package (org.ietf.jgss) either as part of
* the standard JRE or in the CLASSPATH the application specifies.
*/
import org.ietf.jgss.*;
public class SimpleServer {
private String serviceName;
private GSSName name;
private GSSCredential cred;
private GSSManager mgr;
...
...
/**
* Wait for client connections, establish security contexts and
* provide service.
*/
private void loop() {
...
...
mgr = GSSManager.getInstance();
name = mgr.createName(serviceName,
GSSName.NT_HOSTBASED_SERVICE);
cred = mgr.createCredential(name,
GSSCredential.INDEFINITE_LIFETIME,
null,
GSSCredential.ACCEPT_ONLY);
// Loop infinitely
while (true) {
Socket s = serverSock.accept();
// Start a new thread to serve this connection
Thread serverThread = new ServerThread(s);
serverThread.start();
}
}
/**
* Inner class ServerThread whose run() method provides the
* secure service to a connection.
*/
private class ServerThread extends Thread {
...
...
/**
* Deals with the connection from one client. It also
* handles all GSSException's thrown while talking to
* this client.
*/
public void run() {
byte[] inToken = null;
byte[] outToken = null;
byte[] buffer;
GSSName peer;
// Container for multiple input-output arguments to and
// from the per-message routines (ie. wrap/unwrap).
MessageProp supplInfo = new MessageProp();
GSSContext secContext = null;
try {
// Now do the context establishment loop
GSSContext context = mgr.createContext(cred);
while (!context.isEstablished()) {
inToken = readGSSToken();
outToken = context.acceptSecContext(inToken, 0,
inToken.length);
if (outToken != null)
writeGSSToken(outToken);
}
// SimpleServer wants confidentiality to be
// available. Check for it.
if (!context.getConfState()){
...
...
}
GSSName peer = context.getSrcName();
Oid mech = context.getMech();
print("Security context established with " +
peer.toString() +
" using underlying mechanism " +
mech.toString() +
" from Provider " +
context.getProvider().getName());
// Now read the bytes sent by the client to be
// processed.
inToken = readGSSToken();
// Unwrap the message
buffer = context.unwrap(inToken, 0, inToken.length,
supplInfo);
// All ok if no exception was thrown!
// Print other supplementary per-message status
// information
print("Message from " +
peer.toString() + " arrived.");
print("Was it encrypted? " +
supplInfo.getPrivacy());
print("Duplicate Token? " +
supplInfo.isDuplicateToken());
print("Old Token? " + supplInfo.isOldToken());
print("Unsequenced Token? " +
supplInfo.isUnseqToken());
print("Gap Token? " + supplInfo.isGapToken());
/*
* Now process the bytes and send back an encrypted
* response.
*/
buffer = serverProcess(buffer);
// Encipher it and send it across
supplInfo.setPrivacy(true); // privacy requested
supplInfo.setQOP(0); // default QOP
outToken = context.wrap(buffer, 0, buffer.length,
supplInfo);
writeGSSToken(outToken);
} catch (GSSException e) {
print("GSS-API Error: " + e.getMessage());
// Alternatively, could call e.getMajorMessage()
// and e.getMinorMessage()
print("Abandoning security context.");
...
...
}
...
...
} // end of run method in ServerThread
} // end of inner class ServerThread
...
...
} // end of class SimpleServer
8. Security Considerations
The Java language security model allows platform providers to have
policy based fine-grained access control over any resource that an
application wants. When using a Java security manager (such as, but
not limited to, the case of applets running in browsers) the
application code is in a sandbox by default.
Administrators of the platform JRE determine what permissions, if
any, are to be given to source from different codebases. Thus the
administrator has to be aware of any special requirements that the
GSS provider might have for system resources. For instance, a
Kerberos provider might wish to make a network connection to the KDC
to obtain initial credentials. This would not be allowed under the
sandbox unless the administrator had granted permissions for this.
Also note that this granting and checking of permissions happens
transparently to the application and is outside the scope of this
document.
The Java language allows administrators to pre-configure a list of
security service providers in the <JRE>/lib/security/java.security
file. At runtime, the system approaches these providers in order of
preference when looking for security related services. Applications
have a means to modify this list through methods in the "Security"
class in the "java.security" package. However, since these
modifications would be visible in the entire JVM and thus affect all
code executing in it, this operation is not available in the sandbox
and requires special permissions to perform. Thus when a GSS
application has special needs that are met by a particular security
provider, it has two choices:
1) To install the provider on a JVM wide basis using the
java.security.Security class and then depend on the system to
find the right provider automatically when the need arises.
(This would require the application to be granted a
"insertProvider SecurityPermission".)
2) To pass an instance of the provider to the local instance of
GSSManager so that only factory calls going through that
GSSManager use the desired provider. (This would not require
any permissions.)
9. Acknowledgments
This proposed API leverages earlier work performed by the IETF's CAT WG as outlined in both RFC 2743 and RFC 2744. Many conceptual definitions, implementation directions, and explanations have been included from these documents. We would like to thank Mike Eisler, Lin Ling, Ram Marti, Michael Saltz and other members of Sun's development team for their helpful input, comments and suggestions. We would also like to thank Joe Salowey, and Michael Smith for many insightful ideas and suggestions that have contributed to this document.10. Bibliography
[GSSAPIv2] Linn, J., "Generic Security Service Application Program Interface, Version 2", RFC 2078, January 1997. [GSSAPIv2-UPDATE] Linn, J., "Generic Security Service Application Program Interface, Version 2, Update 1", RFC 2743, January 2000. [GSSAPI-Cbind] Wray, J., "Generic Security Service API Version 2 : C-bindings", RFC 2744, January 2000. [KERBV5] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", RFC 1964, June 1996. [SPKM] Adams, C., "The Simple Public-Key GSS-API Mechanism", RFC 2025, October 1996.
11. Authors' Addresses
Address comments related to this memorandum to: <cat-ietf@mit.edu> Jack Kabat ValiCert, Inc. 339 N. Bernardo Avenue Mountain View, CA 94043, USA Phone: +1-650-567-5496 EMail: jackk@valicert.com Mayank Upadhyay Sun Microsystems, Inc. 901 San Antonio Road, MS CUP02-102 Palo Alto, CA 94303 Phone: +1-408-517-5956 EMail: mdu@eng.sun.com
12. Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society.