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 2021-02-20 037 */ 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 final String jcaAlg; 057 058 // Alternative JCA name to try 059 String jcaAlgAlt = null; 060 061 PSSParameterSpec pssSpec = null; 062 063 if (alg.equals(JWSAlgorithm.RS256)) { 064 065 jcaAlg = "SHA256withRSA"; 066 067 } else if (alg.equals(JWSAlgorithm.RS384)) { 068 069 jcaAlg = "SHA384withRSA"; 070 071 } else if (alg.equals(JWSAlgorithm.RS512)) { 072 073 jcaAlg = "SHA512withRSA"; 074 075 } else if (alg.equals(JWSAlgorithm.PS256)) { 076 077 jcaAlg = "RSASSA-PSS"; // JWA mandates salt length equals hash 078 pssSpec = new PSSParameterSpec("SHA-256", "MGF1", MGF1ParameterSpec.SHA256, 32, 1); 079 080 jcaAlgAlt = "SHA256withRSAandMGF1"; 081 082 } else if (alg.equals(JWSAlgorithm.PS384)) { 083 084 jcaAlg = "RSASSA-PSS"; // JWA mandates salt length equals hash 085 pssSpec = new PSSParameterSpec("SHA-384", "MGF1", MGF1ParameterSpec.SHA384, 48, 1); 086 087 jcaAlgAlt = "SHA384withRSAandMGF1"; 088 089 } else if (alg.equals(JWSAlgorithm.PS512)) { 090 091 jcaAlg = "RSASSA-PSS"; // JWA mandates salt length equals hash 092 pssSpec = new PSSParameterSpec("SHA-512", "MGF1", MGF1ParameterSpec.SHA512, 64, 1); 093 094 jcaAlgAlt = "SHA512withRSAandMGF1"; 095 096 } else { 097 throw new JOSEException(AlgorithmSupportMessage.unsupportedJWSAlgorithm(alg, RSASSAProvider.SUPPORTED_ALGORITHMS)); 098 } 099 100 Signature signature; 101 try { 102 signature = getSignerAndVerifier(jcaAlg, provider); 103 104 } catch (NoSuchAlgorithmException e) { 105 106 if (jcaAlgAlt == null) { 107 throw new JOSEException("Unsupported RSASSA algorithm: " + e.getMessage(), e); 108 } 109 110 // Retry with alternative JCA name 111 try { 112 signature = getSignerAndVerifier(jcaAlgAlt, provider); 113 } catch (NoSuchAlgorithmException e2) { 114 throw new JOSEException("Unsupported RSASSA algorithm (after retry with alternative): " + e2.getMessage(), e2); 115 } 116 } 117 118 if (pssSpec != null) { 119 try { 120 signature.setParameter(pssSpec); 121 } catch (InvalidAlgorithmParameterException e) { 122 throw new JOSEException("Invalid RSASSA-PSS salt length parameter: " + e.getMessage(), e); 123 } 124 } 125 126 return signature; 127 } 128 129 130 private static Signature getSignerAndVerifier(final String jcaAlg, final Provider provider) 131 throws NoSuchAlgorithmException { 132 133 if (provider != null) { 134 return Signature.getInstance(jcaAlg, provider); 135 } else { 136 return Signature.getInstance(jcaAlg); 137 } 138 } 139 140 141 /** 142 * Prevents public instantiation. 143 */ 144 private RSASSA() { 145 146 } 147}