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gnu.javax.crypto.key.dh

Class DHKeyPairX509Codec

Implemented Interfaces:
IKeyPairCodec
public class DHKeyPairX509Codec
extends Object
implements IKeyPairCodec

Fields inherited from interface gnu.java.security.key.IKeyPairCodec

ASN1_FORMAT, PKCS8_FORMAT, RAW_FORMAT, X509_FORMAT

Method Summary

PrivateKey
decodePrivateKey(byte[] input)
PublicKey
decodePublicKey(byte[] input)
byte[]
encodePrivateKey(PrivateKey key)
byte[]
encodePublicKey(PublicKey key)
Returns the DER-encoded form of the X.509 ASN.1 SubjectPublicKeyInfo representation of a DH public key.
int
getFormatID()

Methods inherited from class java.lang.Object

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

Method Details

decodePrivateKey

public PrivateKey decodePrivateKey(byte[] input)
Specified by:
decodePrivateKey in interface IKeyPairCodec
Throws:
InvalidParameterException - ALWAYS.

decodePublicKey

public PublicKey decodePublicKey(byte[] input)
Specified by:
decodePublicKey in interface IKeyPairCodec
Parameters:
input - the byte array to unmarshall into a valid DH PublicKey instance. MUST NOT be null.
Returns:
a new instance of a GnuDHPublicKey decoded from the SubjectPublicKeyInfo material in an X.509 certificate.

encodePrivateKey

public byte[] encodePrivateKey(PrivateKey key)
Specified by:
encodePrivateKey in interface IKeyPairCodec
Throws:
InvalidParameterException - ALWAYS.

encodePublicKey

public byte[] encodePublicKey(PublicKey key)
Returns the DER-encoded form of the X.509 ASN.1 SubjectPublicKeyInfo representation of a DH public key. The ASN.1 specification, as defined in RFC-3280, and RFC-2459, is as follows: 
   SubjectPublicKeyInfo ::= SEQUENCE {
     algorithm         AlgorithmIdentifier,
     subjectPublicKey  BIT STRING
   }

   AlgorithmIdentifier ::= SEQUENCE {
     algorithm   OBJECT IDENTIFIER,
     parameters  ANY DEFINED BY algorithm OPTIONAL
   }

   DhParams ::= SEQUENCE {
     p  INTEGER, -- odd prime, p=jq +1
     g  INTEGER, -- generator, g
     q  INTEGER  -- factor of p-1
   }

The subjectPublicKey field, which is a BIT STRING, contains the DER-encoded form of the DH public key as an INTEGER. 

       DHPublicKey ::= INTEGER -- public key, y = g^x mod p

IMPORTANT: with RI's DHGenParameterSpec and DHParameterSpec classes, we may end up with Diffie-Hellman keys that have a null for the q parameter. RFC-2631 DOES NOT allow for an optional value for that parameter, hence we replace such null values with 0, and do the reverse in the corresponding decode method.

Specified by:
encodePublicKey in interface IKeyPairCodec
Parameters:
key - the PublicKey instance to encode. MUST be an instance of GnuDHPublicKey.
Returns:
the DER-encoded form of the ASN.1 representation of the SubjectPublicKeyInfo in an X.509 certificate.

getFormatID

public int getFormatID()
Specified by:
getFormatID in interface IKeyPairCodec
DHKeyPairX509Codec.java -- X.509 DER encoder/decoder for DH keys Copyright (C) 2006 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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