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 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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/*
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/*
 * $Id: DOMDigestMethod.java 1333415 2012-05-03 12:03:51Z coheigea $
 */
package org.jcp.xml.dsig.internal.dom;

import javax.xml.crypto.*;
import javax.xml.crypto.dom.DOMCryptoContext;
import javax.xml.crypto.dsig.*;
import javax.xml.crypto.dsig.spec.DigestMethodParameterSpec;

import java.security.InvalidAlgorithmParameterException;
import java.security.spec.AlgorithmParameterSpec;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;


DOM-based abstract implementation of DigestMethod.

Author:Sean Mullan
/**
 * DOM-based abstract implementation of DigestMethod.
 *
 * @author Sean Mullan
 */
public abstract class DOMDigestMethod extends DOMStructure
    implements DigestMethod {

    static final String SHA384 =
        "http://www.w3.org/2001/04/xmldsig-more#sha384"; // see RFC 4051
    private DigestMethodParameterSpec params;

    
Creates a DOMDigestMethod.

Params:
  • params – the algorithm-specific params (may be null)
Throws:
/**
     * Creates a <code>DOMDigestMethod</code>.
     *
     * @param params the algorithm-specific params (may be <code>null</code>)
     * @throws InvalidAlgorithmParameterException if the parameters are not
     *    appropriate for this digest method
     */
    DOMDigestMethod(AlgorithmParameterSpec params)
        throws InvalidAlgorithmParameterException
    {
        if (params != null && !(params instanceof DigestMethodParameterSpec)) {
            throw new InvalidAlgorithmParameterException
                ("params must be of type DigestMethodParameterSpec");
        }
        checkParams((DigestMethodParameterSpec)params);
        this.params = (DigestMethodParameterSpec)params;
    }

    
Creates a DOMDigestMethod from an element. This constructor invokes the abstract unmarshalParams method to unmarshal any algorithm-specific input parameters. 
Params:
  • dmElem – a DigestMethod element
/**
     * Creates a <code>DOMDigestMethod</code> from an element. This constructor
     * invokes the abstract {@link #unmarshalParams unmarshalParams} method to
     * unmarshal any algorithm-specific input parameters.
     *
     * @param dmElem a DigestMethod element
     */
    DOMDigestMethod(Element dmElem) throws MarshalException {
        Element paramsElem = DOMUtils.getFirstChildElement(dmElem);
        if (paramsElem != null) {
            params = unmarshalParams(paramsElem);
        }
        try {
            checkParams(params);
        } catch (InvalidAlgorithmParameterException iape) {
            throw new MarshalException(iape);
        }
    }

    static DigestMethod unmarshal(Element dmElem) throws MarshalException {
        String alg = DOMUtils.getAttributeValue(dmElem, "Algorithm");
        if (alg.equals(DigestMethod.SHA1)) {
            return new SHA1(dmElem);
        } else if (alg.equals(DigestMethod.SHA256)) {
            return new SHA256(dmElem);
        } else if (alg.equals(SHA384)) {
            return new SHA384(dmElem);
        } else if (alg.equals(DigestMethod.SHA512)) {
            return new SHA512(dmElem);
        } else {
            throw new MarshalException("unsupported DigestMethod algorithm: " +
                                       alg);
        }
    }

    
Checks if the specified parameters are valid for this algorithm. By
default, this method throws an exception if parameters are specified
since most DigestMethod algorithms do not have parameters. Subclasses
should override it if they have parameters.

Params:
  • params – the algorithm-specific params (may be null)
Throws:
/**
     * Checks if the specified parameters are valid for this algorithm. By
     * default, this method throws an exception if parameters are specified
     * since most DigestMethod algorithms do not have parameters. Subclasses
     * should override it if they have parameters.
     *
     * @param params the algorithm-specific params (may be <code>null</code>)
     * @throws InvalidAlgorithmParameterException if the parameters are not
     *    appropriate for this digest method
     */
    void checkParams(DigestMethodParameterSpec params)
        throws InvalidAlgorithmParameterException
    {
        if (params != null) {
            throw new InvalidAlgorithmParameterException("no parameters " +
                "should be specified for the " + getMessageDigestAlgorithm() +
                " DigestMethod algorithm");
        }
    }

    public final AlgorithmParameterSpec getParameterSpec() {
        return params;
    }

    
Unmarshals DigestMethodParameterSpec from the specified
Element.  By default, this method throws an exception since
most DigestMethod algorithms do not have parameters. Subclasses should
override it if they have parameters.

Params:
  • paramsElem – the Element holding the input params
Throws:
Returns:the algorithm-specific DigestMethodParameterSpec
/**
     * Unmarshals <code>DigestMethodParameterSpec</code> from the specified
     * <code>Element</code>.  By default, this method throws an exception since
     * most DigestMethod algorithms do not have parameters. Subclasses should
     * override it if they have parameters.
     *
     * @param paramsElem the <code>Element</code> holding the input params
     * @return the algorithm-specific <code>DigestMethodParameterSpec</code>
     * @throws MarshalException if the parameters cannot be unmarshalled
     */
    DigestMethodParameterSpec unmarshalParams(Element paramsElem)
        throws MarshalException
    {
        throw new MarshalException("no parameters should " +
                                   "be specified for the " +
                                   getMessageDigestAlgorithm() +
                                   " DigestMethod algorithm");
    }

    
This method invokes the abstract marshalParams method to marshal any algorithm-specific parameters. 
/**
     * This method invokes the abstract {@link #marshalParams marshalParams}
     * method to marshal any algorithm-specific parameters.
     */
    public void marshal(Node parent, String prefix, DOMCryptoContext context)
        throws MarshalException
    {
        Document ownerDoc = DOMUtils.getOwnerDocument(parent);

        Element dmElem = DOMUtils.createElement(ownerDoc, "DigestMethod",
                                                XMLSignature.XMLNS, prefix);
        DOMUtils.setAttribute(dmElem, "Algorithm", getAlgorithm());

        if (params != null) {
            marshalParams(dmElem, prefix);
        }

        parent.appendChild(dmElem);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }

        if (!(o instanceof DigestMethod)) {
            return false;
        }
        DigestMethod odm = (DigestMethod)o;

        boolean paramsEqual = (params == null ? odm.getParameterSpec() == null :
            params.equals(odm.getParameterSpec()));

        return (getAlgorithm().equals(odm.getAlgorithm()) && paramsEqual);
    }

    @Override
    public int hashCode() {
        int result = 17;
        if (params != null) {
            result = 31 * result + params.hashCode();
        }
        result = 31 * result + getAlgorithm().hashCode();

        return result;
    }

    
Marshals the algorithm-specific parameters to an Element and
appends it to the specified parent element. By default, this method
throws an exception since most DigestMethod algorithms do not have
parameters. Subclasses should override it if they have parameters.

Params:
  • parent – the parent element to append the parameters to
  • the – namespace prefix to use
Throws:
/**
     * Marshals the algorithm-specific parameters to an Element and
     * appends it to the specified parent element. By default, this method
     * throws an exception since most DigestMethod algorithms do not have
     * parameters. Subclasses should override it if they have parameters.
     *
     * @param parent the parent element to append the parameters to
     * @param the namespace prefix to use
     * @throws MarshalException if the parameters cannot be marshalled
     */
    void marshalParams(Element parent, String prefix)
        throws MarshalException
    {
        throw new MarshalException("no parameters should " +
                                   "be specified for the " +
                                   getMessageDigestAlgorithm() +
                                   " DigestMethod algorithm");
    }

    
Returns the MessageDigest standard algorithm name.

/**
     * Returns the MessageDigest standard algorithm name.
     */
    abstract String getMessageDigestAlgorithm();

    static final class SHA1 extends DOMDigestMethod {
        SHA1(AlgorithmParameterSpec params)
            throws InvalidAlgorithmParameterException {
            super(params);
        }
        SHA1(Element dmElem) throws MarshalException {
            super(dmElem);
        }
        public String getAlgorithm() {
            return DigestMethod.SHA1;
        }
        String getMessageDigestAlgorithm() {
            return "SHA-1";
        }
    }

    static final class SHA256 extends DOMDigestMethod {
        SHA256(AlgorithmParameterSpec params)
            throws InvalidAlgorithmParameterException {
            super(params);
        }
        SHA256(Element dmElem) throws MarshalException {
            super(dmElem);
        }
        public String getAlgorithm() {
            return DigestMethod.SHA256;
        }
        String getMessageDigestAlgorithm() {
            return "SHA-256";
        }
    }

    static final class SHA384 extends DOMDigestMethod {
        SHA384(AlgorithmParameterSpec params)
            throws InvalidAlgorithmParameterException {
            super(params);
        }
        SHA384(Element dmElem) throws MarshalException {
            super(dmElem);
        }
        public String getAlgorithm() {
            return SHA384;
        }
        String getMessageDigestAlgorithm() {
            return "SHA-384";
        }
    }

    static final class SHA512 extends DOMDigestMethod {
        SHA512(AlgorithmParameterSpec params)
            throws InvalidAlgorithmParameterException {
            super(params);
        }
        SHA512(Element dmElem) throws MarshalException {
            super(dmElem);
        }
        public String getAlgorithm() {
            return DigestMethod.SHA512;
        }
        String getMessageDigestAlgorithm() {
            return "SHA-512";
        }
    }
}