ShowSignature.java Source code

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Here is the source code for ShowSignature.java

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/*
 * 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.
 */

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.util.Collection;

import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSString;
import org.apache.pdfbox.pdmodel.PDDocument;

/**
 * This will read a document from the filesystem, decrypt it and do something with the signature.
 *
 * @author Ben Litchfield
 */
public final class ShowSignature {
    private ShowSignature() {
    }

    /**
     * This is the entry point for the application.
     *
     * @param args The command-line arguments.
     *
     * @throws IOException If there is an error reading the file.
     * @throws CertificateException
     */
    public static void main(String[] args) throws IOException, CertificateException {
        ShowSignature show = new ShowSignature();
        show.showSignature(args);
    }

    private void showSignature(String[] args) throws IOException, CertificateException {
        if (args.length != 2) {
            usage();
        } else {
            String password = args[0];
            String infile = args[1];
            PDDocument document = null;
            try {
                document = PDDocument.load(new File(infile), password);
                if (!document.isEncrypted()) {
                    System.err.println("Warning: Document is not encrypted.");
                }

                COSDictionary trailer = document.getDocument().getTrailer();
                COSDictionary root = (COSDictionary) trailer.getDictionaryObject(COSName.ROOT);
                COSDictionary acroForm = (COSDictionary) root.getDictionaryObject(COSName.ACRO_FORM);
                COSArray fields = (COSArray) acroForm.getDictionaryObject(COSName.FIELDS);
                for (int i = 0; i < fields.size(); i++) {
                    COSDictionary field = (COSDictionary) fields.getObject(i);
                    COSName type = field.getCOSName(COSName.FT);
                    if (COSName.SIG.equals(type)) {
                        COSDictionary cert = (COSDictionary) field.getDictionaryObject(COSName.V);
                        if (cert != null) {
                            System.out.println("Certificate found");
                            System.out.println("Name=" + cert.getDictionaryObject(COSName.NAME));
                            System.out.println("Modified=" + cert.getDictionaryObject(COSName.M));
                            COSName subFilter = (COSName) cert.getDictionaryObject(COSName.SUB_FILTER);
                            if (subFilter != null) {
                                if (subFilter.getName().equals("adbe.x509.rsa_sha1")) {
                                    COSString certString = (COSString) cert
                                            .getDictionaryObject(COSName.getPDFName("Cert"));
                                    byte[] certData = certString.getBytes();
                                    CertificateFactory factory = CertificateFactory.getInstance("X.509");
                                    ByteArrayInputStream certStream = new ByteArrayInputStream(certData);
                                    Collection<? extends Certificate> certs = factory
                                            .generateCertificates(certStream);
                                    System.out.println("certs=" + certs);
                                } else if (subFilter.getName().equals("adbe.pkcs7.sha1")) {
                                    COSString certString = (COSString) cert.getDictionaryObject(COSName.CONTENTS);
                                    byte[] certData = certString.getBytes();
                                    CertificateFactory factory = CertificateFactory.getInstance("X.509");
                                    ByteArrayInputStream certStream = new ByteArrayInputStream(certData);
                                    Collection<? extends Certificate> certs = factory
                                            .generateCertificates(certStream);
                                    System.out.println("certs=" + certs);
                                } else {
                                    System.err.println("Unknown certificate type:" + subFilter);
                                }
                            } else {
                                throw new IOException("Missing subfilter for cert dictionary");
                            }
                        } else {
                            System.out.println("Signature found, but no certificate");
                        }
                    }
                }
            } finally {
                if (document != null) {
                    document.close();
                }
            }
        }
    }

    /**
     * This will print a usage message.
     */
    private static void usage() {
        System.err.println("usage: java " + ShowSignature.class.getName() + "<password> <inputfile>");
    }
}