PDSignature.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information 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 with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.pdfbox.pdmodel.interactive.digitalsignature;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Calendar;

import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSBase;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSInteger;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSString;
import org.apache.pdfbox.pdfwriter.COSFilterInputStream;
import org.apache.pdfbox.pdmodel.common.COSObjectable;

/**
 * This represents a digital signature that can be attached to a document.
 * 
 * @author <a href="mailto:ben@benlitchfield.com">Ben Litchfield</a>
 * @author Thomas Chojecki
 * @version $Revision: 1.2 $
 */
public class PDSignature implements COSObjectable
{

  private COSDictionary dictionary;

  /**
   * A signature filter value.
   */
  public static final COSName FILTER_ADOBE_PPKLITE = COSName.ADOBE_PPKLITE;

  /**
   * A signature filter value.
   */
  public static final COSName FILTER_ENTRUST_PPKEF = COSName.ENTRUST_PPKEF;

  /**
   * A signature filter value.
   */
  public static final COSName FILTER_CICI_SIGNIT = COSName.CICI_SIGNIT;

  /**
   * A signature filter value.
   */
  public static final COSName FILTER_VERISIGN_PPKVS = COSName.VERISIGN_PPKVS;

  /**
   * A signature subfilter value.
   */
  public static final COSName SUBFILTER_ADBE_X509_RSA_SHA1 = COSName.ADBE_X509_RSA_SHA1;

  /**
   * A signature subfilter value.
   */
  public static final COSName SUBFILTER_ADBE_PKCS7_DETACHED = COSName.ADBE_PKCS7_DETACHED;

  /**
   * A signature subfilter value.
   */
  public static final COSName SUBFILTER_ETSI_CADES_DETACHED = COSName.getPDFName("ETSI.CAdES.detached");

  /**
   * A signature subfilter value.
   */
  public static final COSName SUBFILTER_ADBE_PKCS7_SHA1 = COSName.ADBE_PKCS7_SHA1;

  /**
   * Default constructor.
   */
  public PDSignature()
  {
    dictionary = new COSDictionary();
    dictionary.setItem(COSName.TYPE, COSName.SIG);
  }

  /**
   * Constructor.
   * 
   * @param dict The signature dictionary.
   */
  public PDSignature(COSDictionary dict)
  {
    dictionary = dict;
  }

  /**
   * Convert this standard java object to a COS object.
   * 
   * @return The cos object that matches this Java object.
   */
  public COSBase getCOSObject()
  {
    return getDictionary();
  }

  /**
   * Convert this standard java object to a COS dictionary.
   * 
   * @return The COS dictionary that matches this Java object.
   */
  public COSDictionary getDictionary()
  {
    return dictionary;
  }

  public void setFilter(COSName filter)
  {
    dictionary.setItem(COSName.FILTER, filter);
  }

  /**
   * Set a subfilter that specify the signature that should be used. 
   * 
   * @param subfilter the subfilter that shall be used.
   */
  public void setSubFilter(COSName subfilter)
  {
    dictionary.setItem(COSName.SUBFILTER, subfilter);
  }

  public void setName(String name)
  {
    dictionary.setString(COSName.NAME, name);
  }

  public void setLocation(String location)
  {
    dictionary.setString(COSName.LOCATION, location);
  }

  public void setReason(String reason)
  {
    dictionary.setString(COSName.REASON, reason);
  }

  public void setSignDate(Calendar cal)
  {
    dictionary.setDate("M", cal);
  }

  public String getFilter()
  {
    return ((COSName)dictionary.getItem(COSName.FILTER)).getName();
  }

  public String getSubFilter()
  {
    return ((COSName)dictionary.getItem(COSName.SUBFILTER)).getName();
  }

  public String getName()
  {
    return dictionary.getString(COSName.NAME);
  }

  public String getLocation()
  {
    return dictionary.getString(COSName.LOCATION);
  }

  public String getReason()
  {
    return dictionary.getString(COSName.REASON);
  }

  public Calendar getSignDate()
  {
    try
    {
      return dictionary.getDate("M");
    }
    catch (IOException e)
    {
      return null;
    }
  }

  public void setByteRange(int[] range) 
  {
    if (range.length!=4)
      return;

    COSArray ary = new COSArray();
    for ( int i : range )
    {
      ary.add(COSInteger.get(i));
    }
    
    dictionary.setItem("ByteRange", ary);
  }

  /**
   * Read out the byterange from the file
   * 
   * @return a integer array with the byterange
   */
  public int[] getByteRange()
  {
    COSArray byteRange = (COSArray)dictionary.getDictionaryObject("ByteRange");
    int[] ary = new int[byteRange.size()];
    for (int i = 0; i<ary.length;++i)
      ary[i] = byteRange.getInt(i);
    
    return ary;
  }
  
  /**
   * Will return the embedded signature between the byterange gap.
   * 
   * @param pdfFile The signed pdf file as InputStream
   * @return a byte array containing the signature
   * @throws IOException if the pdfFile can't be read
   */
  public byte[] getContents(InputStream pdfFile) throws IOException
  {
    int[] byteRange = getByteRange();
    int begin = byteRange[0]+byteRange[1]+1;
    int end = byteRange[2]-begin;
    
    return getContents(new COSFilterInputStream(pdfFile,new int[] {begin,end}));
  }
  
  /**
   * Will return the embedded signature between the byterange gap.
   * 
   * @param pdfFile The signed pdf file as byte array
   * @return a byte array containing the signature
   * @throws IOException if the pdfFile can't be read
   */
  public byte[] getContents(byte[] pdfFile) throws IOException
  {
    int[] byteRange = getByteRange();
    int begin = byteRange[0]+byteRange[1]+1;
    int end = byteRange[2]-begin;
    
    return getContents(new COSFilterInputStream(pdfFile,new int[] {begin,end}));
  }

  private byte[] getContents(COSFilterInputStream fis) throws IOException 
  {
    ByteArrayOutputStream byteOS = new ByteArrayOutputStream(1024);
    byte[] buffer = new byte[1024];
    int c;
    while ((c = fis.read(buffer)) != -1)
    {
      // Filter < and (
      if(buffer[0]==0x3C || buffer[0]==0x28)
        byteOS.write(buffer, 1, c);
      // Filter > and )
      else if(buffer[c-1]==0x3E || buffer[c-1]==0x29)
        byteOS.write(buffer, 0, c-1);
      else 
        byteOS.write(buffer, 0, c);
    }
    fis.close();
    
    return COSString.createFromHexString(byteOS.toString()).getBytes();
  }
  
  public void setContents(byte[] bytes)
  {
    COSString string = new COSString(bytes);
    string.setForceHexForm(true);
    dictionary.setItem("Contents", string);
  }
  
  /**
   * Will return the signed content of the document.
   * 
   * @param pdfFile The signed pdf file as InputStream
   * @return a byte array containing only the signed part of the content
   * @throws IOException if the pdfFile can't be read
   */
  public byte[] getSignedContent(InputStream pdfFile) throws IOException
  {
    COSFilterInputStream fis=null;
    
    try 
    {
    fis = new COSFilterInputStream(pdfFile,getByteRange());
    return fis.toByteArray();
    } 
    finally 
    {
      if (fis != null)
        fis.close();
    }
  }
  
  /**
   * Will return the signed content of the document.
   * 
   * @param pdfFile The signed pdf file as byte array
   * @return a byte array containing only the signed part of the content
   * @throws IOException if the pdfFile can't be read
   */
  public byte[] getSignedContent(byte[] pdfFile) throws IOException
  {
    COSFilterInputStream fis=null;
    
    try 
    {
    fis = new COSFilterInputStream(pdfFile,getByteRange());
    return fis.toByteArray();
    } 
    finally 
    {
      if (fis != null)
        fis.close();
    }
  }
}