Java tutorial
/* * * This file is part of the iText (R) project. Copyright (c) 1998-2019 iText Group NV * Authors: Bruno Lowagie, Paulo Soares, et al. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License version 3 * as published by the Free Software Foundation with the addition of the * following permission added to Section 15 as permitted in Section 7(a): * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT * OF THIRD PARTY RIGHTS * * This program 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 Affero General Public License for more details. * You should have received a copy of the GNU Affero General Public License * along with this program; if not, see http://www.gnu.org/licenses or write to * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, * Boston, MA, 02110-1301 USA, or download the license from the following URL: * http://itextpdf.com/terms-of-use/ * * The interactive user interfaces in modified source and object code versions * of this program must display Appropriate Legal Notices, as required under * Section 5 of the GNU Affero General Public License. * * In accordance with Section 7(b) of the GNU Affero General Public License, * a covered work must retain the producer line in every PDF that is created * or manipulated using iText. * * You can be released from the requirements of the license by purchasing * a commercial license. Buying such a license is mandatory as soon as you * develop commercial activities involving the iText software without * disclosing the source code of your own applications. * These activities include: offering paid services to customers as an ASP, * serving PDFs on the fly in a web application, shipping iText with a closed * source product. * * For more information, please contact iText Software Corp. at this * address: sales@itextpdf.com */ package com.itextpdf.text.pdf.security; import java.security.GeneralSecurityException; import java.security.MessageDigest; /** * Time Stamp Authority client (caller) interface. * <p> * Interface used by the PdfPKCS7 digital signature builder to call * Time Stamp Authority providing RFC 3161 compliant time stamp token. * @author Martin Brunecky, 07/17/2007 * @since 2.1.6 */ public interface TSAClient { /** * Get the time stamp token size estimate. * Implementation must return value large enough to accomodate the entire token * returned by getTimeStampToken() _prior_ to actual getTimeStampToken() call. * @return an estimate of the token size */ public int getTokenSizeEstimate(); /** * Gets the MessageDigest to digest the data imprint * @return the digest algorithm name */ public MessageDigest getMessageDigest() throws GeneralSecurityException; /** * Get RFC 3161 timeStampToken. * Method may return null indicating that timestamp should be skipped. * @param imprint byte[] - data imprint to be time-stamped * @return byte[] - encoded, TSA signed data of the timeStampToken * @throws Exception - TSA request failed */ public byte[] getTimeStampToken(byte[] imprint) throws Exception; }