Class RSAPKCS1V1_5SignatureX509Codec

Implemented Interfaces:

public class RSAPKCS1V1_5SignatureX509Codec
extends Object
implements ISignatureCodec

An implementation of an ISignatureCodec that knows to encode and decode RSA PKCS1 (v1.5) signatures into the raw bytes which would constitute a DER-encoded form of the ASN.1 structure defined in RFC-2459, and RFC-2313 as described in the next paragraphs.

Digital signatures when transmitted in an X.509 certificates are encoded in DER (Distinguished Encoding Rules) as a BIT STRING; i.e.

 Certificate ::= SEQUENCE {
   tbsCertificate       TBSCertificate,
   signatureAlgorithm   AlgorithmIdentifier,
   signature            BIT STRING

The output of the encoder, and the input of the decoder, of this codec are then the raw bytes of such a BIT STRING; i.e. not the DER-encoded form itself.

Our implementation of the RSA PKCS1 signature algorithm outputs a byte array as the result of generating a digital signature, in accordance with RFC-2313. As a consequence, the encoder and decoder of this codec, simply pass through such a byte array.

Client code that needs to build a DER BIT STRING MUST construct such an ASN.1 value. The following is an example of how to do this:

 DERValue bitString = new DERValue(DER.BIT_STRING, new BitString(sigBytes));

Fields inherited from interface


Method Summary

decodeSignature(byte[] input)
Decodes a signature as defined in the documentation of this class.
encodeSignature(Object signature)
Encodes an RSA Signature output as a signature BIT STRING as defined in the documentation of this class.

Methods inherited from class java.lang.Object

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

Method Details


public Object decodeSignature(byte[] input)
Decodes a signature as defined in the documentation of this class.
Specified by:
decodeSignature in interface ISignatureCodec
input - the byte array to unmarshall into a valid RSA PKCS1 (v1.5) signature instance; i.e. a byte array. MUST NOT be null.
an array of raw bytes decoded from the designated input. In the case of RSA PKCS1 (v1.5) this is the same as the input.


public byte[] encodeSignature(Object signature)
Encodes an RSA Signature output as a signature BIT STRING as defined in the documentation of this class.
Specified by:
encodeSignature in interface ISignatureCodec
signature - the output of the RSA PKCS1 (v1.5) signature algorithm; i.e. the value returned by the invocation of ISignature.sign() method. In the case of the RSA PKCS1 (v1.5) signature this is an array of bytes.
the raw bytes of an RSA signature which could be then used as the contents of a BIT STRING as per rfc-2459.


public int getFormatID()
Specified by:
getFormatID in interface ISignatureCodec -- X.509 encoder/decoder for RSA signatures 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.