using System;
/*
 * $Id: ITSAClient.cs 106 2009-12-07 12:23:50Z psoares33 $
 *
 * This file is part of the iText project.
 * Copyright (c) 1998-2012 1T3XT BVBA
 * 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 1T3XT,
 * 1T3XT 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,
 * you 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
 */

namespace iTextSharp.text.pdf {

    /**
    * 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 ITSAClient {
        /**
        * 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
        */
        int GetTokenSizeEstimate();
        
        /**
         * Gets the algorithm used to digest the data imprint
         * @return the digest algorithm name
         */
        String GetDigestAlgorithm();

        /**
         * 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
         */
        byte[] GetTimeStampToken(byte[] imprint);
    }
}
