SignatureValue.java

/*
 * SignatureValue.java
 * PROJECT: JDigiDoc
 * DESCRIPTION: Digi Doc functions for creating
 *	and reading signed documents. 
 * AUTHOR:  Veiko Sinivee, S|E|B IT Partner Estonia
 *==================================================
 * Copyright (C) AS Sertifitseerimiskeskus
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * This library 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
 * Lesser General Public License for more details.
 * GNU Lesser General Public Licence is available at
 * http://www.gnu.org/copyleft/lesser.html
 *==================================================
 */

package ee.sk.digidoc;
import java.io.Serializable;
import java.util.ArrayList;
import ee.sk.utils.ConvertUtils;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * Models the SignatureValue element of
 * XML-DSIG
 * @author  Veiko Sinivee
 * @version 1.0
 */
public class SignatureValue implements Serializable
{
	private static final long serialVersionUID = 1L;
    /** signature value id */
    private String m_id;
    /** actual signature value data */
    private byte[] m_value;
    private Signature m_sig;
    
    /** RSA signatures have 128 bytes */
    public static final int SIGNATURE_VALUE_LENGTH = 128;
    
    
    /** 
     * Creates new SignatureValue 
     */
    public SignatureValue() {
        m_id = null;
        m_value = null;
    }
    
    /** 
     * Creates new SignatureValue 
     * @param id SignatureValue id
     * @param value actual RSA signature value
     * @throws DigiDocException for validation errors
     */
    public SignatureValue(String id, byte[] value, boolean isEC)
        throws DigiDocException
    {
        setId(id);
        setValue(value, isEC);
    }

    /** 
     * Creates new SignatureValue 
     * @param id SignatureValue id
     * @param value actual RSA signature value
     * @throws DigiDocException for validation errors
     */
    public SignatureValue(Signature sig, byte[] value)
        throws DigiDocException
    {
        setId(sig.getId() + "-SIG");
        m_sig = sig;
        setValue(value, sig.isEllipticCurveSiganture());
    }
    
    /** 
     * Creates new SignatureValue 
     * @param id SignatureValue id
     * @throws DigiDocException for validation errors
     */
    public SignatureValue(Signature sig, String id)
        throws DigiDocException
    {
    	m_sig = sig;
        if(id != null)
    		setId(id);
    	else
    		setId(sig.getId() + "-SIG");
        sig.setSignatureValue(this);
    }
    
    /**
     * Accessor for id attribute
     * @return value of id attribute
     */
    public String getId() {
        return m_id;
    }
    
    /**
     * Mutator for id attribute
     * @param str new value for id attribute
     * @throws DigiDocException for validation errors
     */    
    public void setId(String str) 
        throws DigiDocException
    {
        DigiDocException ex = validateId(str);
        if(ex != null)
            throw ex;
        m_id = str;
    }
    
    /**
     * Helper method to validate an id
     * @param str input data
     * @return exception or null for ok
     */
    private DigiDocException validateId(String str)
    {
        DigiDocException ex = null;
        if(str == null)
            ex = new DigiDocException(DigiDocException.ERR_SIGNATURE_VALUE_ID, 
                "Id is a required attribute", null);
        return ex;
    }

    /**
     * Accessor for value attribute
     * @return value of value attribute
     */
    public byte[] getValue() {
        return m_value;
    }
    
    /**
     * Mutator for value attribute
     * @param str new value for value attribute
     * @throws DigiDocException for validation errors
     */    
    public void setValue(byte[] data, boolean isEC) 
        throws DigiDocException
    {
        DigiDocException ex = validateValue(data, isEC);
        if(ex != null)
            throw ex;
        m_value = data;
    }
    
    /**
     * Helper method to validate a signature value
     * @param str input data
     * @return exception or null for ok
     */
    private DigiDocException validateValue(byte[] value, boolean isEC)
    {
        DigiDocException ex = null;
        if(value == null || (value.length < SIGNATURE_VALUE_LENGTH && !isEC))
            ex = new DigiDocException(DigiDocException.ERR_SIGNATURE_VALUE_ID, 
                "RSA signature value must be at least 128 bytes", null);
        return ex;
    }

    /**
     * Helper method to validate the whole
     * SignatureValue object
     * @return a possibly empty list of DigiDocException objects
     */
    public ArrayList validate()
    {
        ArrayList errs = new ArrayList();
        // VS: 2.3.24 - fix to allowe SignatureValue without Id atribute
		DigiDocException ex = validateValue(m_value, (m_sig != null) ? m_sig.isEllipticCurveSiganture() : false);
        if(ex != null)
            errs.add(ex);
        return errs;
    }
    

}