Java tutorial
/** * The MIT License * * Copyright (C) 2015 Asterios Raptis * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ package de.alpharogroup.crypto.key.reader; import java.io.File; import java.io.IOException; import java.nio.file.Files; import java.security.KeyFactory; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.PublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.X509EncodedKeySpec; import org.apache.commons.codec.binary.Base64; import de.alpharogroup.crypto.algorithm.KeyPairGeneratorAlgorithm; import de.alpharogroup.crypto.provider.SecurityProvider; import lombok.experimental.UtilityClass; /** * The class {@link PublicKeyReader} is a utility class for reading public keys. */ @UtilityClass public class PublicKeyReader { /** The Constant END_PUBLIC_KEY_SUFFIX. */ public static final String END_PUBLIC_KEY_SUFFIX = "-----END PUBLIC KEY-----"; /** The Constant BEGIN_PUBLIC_KEY_PREFIX. */ public static final String BEGIN_PUBLIC_KEY_PREFIX = "-----BEGIN PUBLIC KEY-----\n"; /** * Read public key. * * @param file * the file * @return the public key * @throws IOException * Signals that an I/O exception has occurred. * @throws NoSuchAlgorithmException * is thrown if instantiation of the cypher object fails. * @throws InvalidKeySpecException * is thrown if generation of the SecretKey object fails. * @throws NoSuchProviderException * is thrown if the specified provider is not registered in the security provider * list. */ public static PublicKey readPublicKey(final File file) throws IOException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException { final byte[] keyBytes = Files.readAllBytes(file.toPath()); return readPublicKey(keyBytes, "BC"); } /** * Read public key. * * @param publicKeyBytes * the public key bytes * @param securityProvider * the security provider * @return the public key * @throws NoSuchAlgorithmException * is thrown if instantiation of the cypher object fails. * @throws InvalidKeySpecException * is thrown if generation of the SecretKey object fails. * @throws NoSuchProviderException * is thrown if the specified provider is not registered in the security provider * list. */ public static PublicKey readPublicKey(final byte[] publicKeyBytes, final SecurityProvider securityProvider) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException { return readPublicKey(publicKeyBytes, securityProvider.name()); } /** * Read public key. * * @param publicKeyBytes * the public key bytes * @param provider * the provider * @return the public key * @throws NoSuchAlgorithmException * is thrown if instantiation of the cypher object fails. * @throws InvalidKeySpecException * is thrown if generation of the SecretKey object fails. * @throws NoSuchProviderException * is thrown if the specified provider is not registered in the security provider * list. */ public static PublicKey readPublicKey(final byte[] publicKeyBytes, final String provider) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException { return readPublicKey(publicKeyBytes, provider, KeyPairGeneratorAlgorithm.RSA.getAlgorithm()); } /** * Read public key. * * @param publicKeyBytes * the public key bytes * @param provider * the provider * @param algorithm * the algorithm for the {@link KeyFactory} * @return the public key * @throws NoSuchAlgorithmException * is thrown if instantiation of the cypher object fails. * @throws InvalidKeySpecException * is thrown if generation of the SecretKey object fails. * @throws NoSuchProviderException * is thrown if the specified provider is not registered in the security provider * list. */ public static PublicKey readPublicKey(final byte[] publicKeyBytes, final String provider, final String algorithm) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException { final X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes); final KeyFactory keyFactory = KeyFactory.getInstance(algorithm); final PublicKey publicKey = keyFactory.generatePublic(keySpec); return publicKey; } /** * reads a public key from a file. * * @param file * the file * @param securityProvider * the security provider * @return the public key * @throws Exception * is thrown if if a security error occur */ public static PublicKey readPemPublicKey(final File file, final SecurityProvider securityProvider) throws Exception { final String publicKeyAsString = readPemFileAsBase64(file); final byte[] decoded = Base64.decodeBase64(publicKeyAsString); return readPublicKey(decoded, securityProvider); } /** * Read the public key from a pem file as base64 encoded {@link String} value. * * @param file * the file in pem format that contains the public key. * @return the base64 encoded {@link String} value. * @throws IOException * Signals that an I/O exception has occurred. */ public static String readPemFileAsBase64(final File file) throws IOException { final byte[] keyBytes = Files.readAllBytes(file.toPath()); final String publicKeyAsBase64String = new String(keyBytes).replace(BEGIN_PUBLIC_KEY_PREFIX, "") .replace(END_PUBLIC_KEY_SUFFIX, ""); return publicKeyAsBase64String; } /** * reads a public key from a file. * * @param file * the file * @return the public key * @throws Exception * is thrown if if a security error occur */ public static PublicKey readPemPublicKey(final File file) throws Exception { return readPemPublicKey(file, SecurityProvider.BC); } }