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java.security

Class SignedObject

Implemented Interfaces:
Serializable
public final class SignedObject
extends Object
implements Serializable
SignedObject is used for storing runtime objects whose integrity cannot be compromised without being detected.

SignedObject contains a Serializable object which is yet to be signed and a digital signature of that object.

The signed copy is a "deep copy" (in serialized form) of an original object. Any changes to that original instance are not reflected in the enclosed copy inside this SignedObject.

Several things to note are that, first there is no need to initialize the signature engine as this class will handle that automatically. Second, verification will only succeed if the public key corresponds to the private key used to generate the digital signature inside this SignedObject.

For fexibility, the signature engine can be specified in the constructor or the verify() method. Programmers wishing to verify SignedObjects should be aware of the Signature engine they use. A malicious or flawed Signature implementation may always return true on verification thus circumventing the intended secrity check provided by the SignedObject.

The GNU security provider offers an implementation of the standard NIST DSA which uses "DSA" and "SHA-1". It can be specified by "SHA/DSA", "SHA-1/DSA" or its OID. If the RSA signature algorithm is provided then it could be "MD2/RSA". "MD5/RSA", or "SHA-1/RSA". The algorithm must be specified because there is no default.

Since:
1.2
See Also:
Signature, Serialized Form

Constructor Summary

SignedObject(Serializable object, PrivateKey signingKey, Signature signingEngine)
Constructs a new instance of SignedObject from a Serializable object.

Method Summary

String
getAlgorithm()
Returns the name of the signature algorithm.
Object
getObject()
Returns the encapsulated object.
byte[]
getSignature()
Returns the signature bytes of the encapsulated object.
boolean
verify(PublicKey verificationKey, Signature verificationEngine)
Verifies the encapsulated digital signature by checking that it was generated by the owner of a designated public key.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SignedObject

public SignedObject(Serializable object,
                    PrivateKey signingKey,
                    Signature signingEngine)
            throws IOException,
                   InvalidKeyException,
                   SignatureException
Constructs a new instance of SignedObject from a Serializable object. The object is signed with a designated private key and a signature engine.
Parameters:
object - the object to sign.
signingKey - the key to use.
signingEngine - the signature engine to use.
Throws:
IOException - if a serialization error occurred.
InvalidKeyException - if the key is invalid.
SignatureException - if a signing error occurs.

Method Details

getAlgorithm

public String getAlgorithm()
Returns the name of the signature algorithm.
Returns:
the name of the signature algorithm.

getObject

public Object getObject()
            throws IOException,
                   ClassNotFoundException
Returns the encapsulated object. The object is de-serialized before being returned.
Returns:
the encapsulated object.
Throws:
IOException - if a de-serialization error occurs.
ClassNotFoundException - if the encapsulated object's class was not found.

getSignature

public byte[] getSignature()
Returns the signature bytes of the encapsulated object.
Returns:
the signature bytes of the encapsulated object.

verify

public boolean verify(PublicKey verificationKey,
                      Signature verificationEngine)
            throws InvalidKeyException,
                   SignatureException
Verifies the encapsulated digital signature by checking that it was generated by the owner of a designated public key.
Parameters:
verificationKey - the public key to use.
verificationEngine - the signature engine to use.
Returns:
true if signature is correct, false otherwise.
Throws:
InvalidKeyException - if the key is invalid.
SignatureException - if verification fails.
SignedObject.java --- Signed Object Class Copyright (C) 1999, 2003, Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath 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 for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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