Java tutorial
/* * Copyright 2006-2011 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the * specific language governing permissions and limitations under the License. */ package org.springframework.security.jwt.crypto.sign; import java.math.BigInteger; import java.security.*; import java.security.interfaces.RSAPublicKey; /** * Verifies signatures using an RSA public key. * * The key can be supplied directly, or as an SSH public or private key string (in * the standard format produced by <tt>ssh-keygen</tt>). * * @author Luke Taylor */ public class RsaVerifier implements SignatureVerifier { private final RSAPublicKey key; private final String algorithm; public RsaVerifier(BigInteger n, BigInteger e) { this(RsaKeyHelper.createPublicKey(n, e)); } public RsaVerifier(RSAPublicKey key) { this(key, RsaSigner.DEFAULT_ALGORITHM); } public RsaVerifier(RSAPublicKey key, String algorithm) { this.key = key; this.algorithm = algorithm; } public RsaVerifier(String key) { this(RsaKeyHelper.parsePublicKey(key.trim()), RsaSigner.DEFAULT_ALGORITHM); } public void verify(byte[] content, byte[] sig) { try { Signature signature = Signature.getInstance(algorithm); signature.initVerify(key); signature.update(content); if (!signature.verify(sig)) { throw new InvalidSignatureException("RSA Signature did not match content"); } } catch (GeneralSecurityException e) { throw new RuntimeException(e); } } public String algorithm() { return algorithm; } }