001/*
002 * nimbus-jose-jwt
003 *
004 * Copyright 2012-2016, Connect2id Ltd and contributors.
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use
007 * this file except in compliance with the License. You may obtain a copy of the
008 * 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 distributed
013 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
014 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
015 * specific language governing permissions and limitations under the License.
016 */
017
018package com.nimbusds.jose.crypto.impl;
019
020
021import java.security.InvalidAlgorithmParameterException;
022import java.security.NoSuchAlgorithmException;
023import java.security.Provider;
024import java.security.Signature;
025import java.security.spec.MGF1ParameterSpec;
026import java.security.spec.PSSParameterSpec;
027
028import com.nimbusds.jose.JOSEException;
029import com.nimbusds.jose.JWSAlgorithm;
030
031
032/**
033 * RSA-SSA functions and utilities.
034 *
035 * @author Vladimir Dzhuvinov
036 * @version 2015-05-31
037 */
038public class RSASSA {
039
040
041        /**
042         * Returns a signer and verifier for the specified RSASSA-based JSON
043         * Web Algorithm (JWA).
044         *
045         * @param alg The JSON Web Algorithm (JWA). Must be supported and not
046         *            {@code null}.
047         *
048         * @return A signer and verifier instance.
049         *
050         * @throws JOSEException If the algorithm is not supported.
051         */
052        public static Signature getSignerAndVerifier(final JWSAlgorithm alg,
053                                                        final Provider provider)
054                throws JOSEException {
055
056                // The JCE crypto provider uses different alg names
057
058                final String jcaAlg;
059
060                PSSParameterSpec pssSpec = null;
061
062                if (alg.equals(JWSAlgorithm.RS256)) {
063                        jcaAlg = "SHA256withRSA";
064                } else if (alg.equals(JWSAlgorithm.RS384)) {
065                        jcaAlg = "SHA384withRSA";
066                } else if (alg.equals(JWSAlgorithm.RS512)) {
067                        jcaAlg = "SHA512withRSA";
068                } else if (alg.equals(JWSAlgorithm.PS256)) {
069                        jcaAlg = "SHA256withRSAandMGF1";
070                        // JWA mandates salt length must equal hash
071                        pssSpec = new PSSParameterSpec("SHA256", "MGF1", MGF1ParameterSpec.SHA256, 32, 1);
072                } else if (alg.equals(JWSAlgorithm.PS384)) {
073                        jcaAlg = "SHA384withRSAandMGF1";
074                        // JWA mandates salt length must equal hash
075                        pssSpec = new PSSParameterSpec("SHA384", "MGF1", MGF1ParameterSpec.SHA384, 48, 1);
076                } else if (alg.equals(JWSAlgorithm.PS512)) {
077                        jcaAlg = "SHA512withRSAandMGF1";
078                        // JWA mandates salt length must equal hash
079                        pssSpec = new PSSParameterSpec("SHA512", "MGF1", MGF1ParameterSpec.SHA512, 64, 1);
080                } else {
081                        throw new JOSEException(AlgorithmSupportMessage.unsupportedJWSAlgorithm(alg, RSASSAProvider.SUPPORTED_ALGORITHMS));
082                }
083
084                final Signature signature;
085                try {
086                        if (provider != null) {
087                                signature = Signature.getInstance(jcaAlg, provider);
088                        } else {
089                                signature = Signature.getInstance(jcaAlg);
090                        }
091                } catch (NoSuchAlgorithmException e) {
092                        throw new JOSEException("Unsupported RSASSA algorithm: " + e.getMessage(), e);
093                }
094
095
096                if (pssSpec != null) {
097                        try {
098                                signature.setParameter(pssSpec);
099                        } catch (InvalidAlgorithmParameterException e) {
100                                throw new JOSEException("Invalid RSASSA-PSS salt length parameter: " + e.getMessage(), e);
101                        }
102                }
103
104                return signature;
105        }
106
107
108        /**
109         * Prevents public instantiation.
110         */
111        private RSASSA() {
112
113        }
114}