001    /**
002     *
003     *  Licensed to the Apache Software Foundation (ASF) under one or more
004     *  contributor license agreements.  See the NOTICE file distributed with
005     *  this work for additional information regarding copyright ownership.
006     *  The ASF licenses this file to You under the Apache License, Version 2.0
007     *  (the "License"); you may not use this file except in compliance with
008     *  the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     *  Unless required by applicable law or agreed to in writing, software
013     *  distributed under the License is distributed on an "AS IS" BASIS,
014     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     *  See the License for the specific language governing permissions and
016     *  limitations under the License.
017     */
018    
019    package org.apache.geronimo.util.crypto;
020    
021    import java.math.BigInteger;
022    
023    /**
024     * interface for classes implementing algorithms modeled similar to the Digital Signature Alorithm.
025     */
026    public interface DSA
027    {
028        /**
029         * initialise the signer for signature generation or signature
030         * verification.
031         *
032         * @param forSigning true if we are generating a signature, false
033         * otherwise.
034         * @param param key parameters for signature generation.
035         */
036        public void init(boolean forSigning, CipherParameters param);
037    
038        /**
039         * sign the passed in message (usually the output of a hash function).
040         *
041         * @param message the message to be signed.
042         * @return two big integers representing the r and s values respectively.
043         */
044        public BigInteger[] generateSignature(byte[] message);
045    
046        /**
047         * verify the message message against the signature values r and s.
048         *
049         * @param message the message that was supposed to have been signed.
050         * @param r the r signature value.
051         * @param s the s signature value.
052         */
053        public boolean verifySignature(byte[] message, BigInteger  r, BigInteger s);
054    }