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