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; import java.security.KeyFactory; import java.security.NoSuchAlgorithmException; import java.security.PrivateKey; import java.security.PublicKey; import java.security.interfaces.DSAPrivateKey; import java.security.interfaces.ECPrivateKey; import java.security.interfaces.RSAPrivateCrtKey; import java.security.interfaces.RSAPrivateKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.RSAPublicKeySpec; import org.apache.commons.codec.binary.Base64; import de.alpharogroup.crypto.algorithm.KeyPairGeneratorAlgorithm; import de.alpharogroup.crypto.hex.HexExtensions; import lombok.experimental.UtilityClass; /** * The class {@link PrivateKeyExtensions}. */ @UtilityClass public class PrivateKeyExtensions { /** * Gets the key length of the given {@link PrivateKey}. * * @param privateKey * the private key * @return the key length */ public static int getKeyLength(final PrivateKey privateKey) { int length = -1; if (privateKey == null) { return length; } if (privateKey instanceof RSAPrivateKey) { length = ((RSAPrivateKey) privateKey).getModulus().bitLength(); } if (privateKey instanceof DSAPrivateKey) { length = ((DSAPrivateKey) privateKey).getParams().getQ().bitLength(); } if (privateKey instanceof ECPrivateKey) { length = ((ECPrivateKey) privateKey).getParams().getCurve().getField().getFieldSize(); } return length; } /** * Transform the given {@link PrivateKey} to a hexadecimal {@link String} value. * * @param privateKey * the private key * @return the new hexadecimal {@link String} value. */ public static String toHexString(final PrivateKey privateKey) { return toHexString(privateKey, true); } /** * Transform the given {@link PrivateKey} to a hexadecimal {@link String} value. * * @param privateKey * the private key * @param lowerCase * the flag if the result shell be transform in lower case. If true the result is * @return the new hexadecimal {@link String} value. */ public static String toHexString(final PrivateKey privateKey, final boolean lowerCase) { final String hexString = HexExtensions.toHexString(privateKey.getEncoded(), lowerCase); return hexString; } /** * Transform the given {@link PrivateKey} to a base64 encoded {@link String} value. * * @param privateKey * the private key * @return the new base64 encoded {@link String} value. */ public static String toBase64(final PrivateKey privateKey) { final byte[] encoded = privateKey.getEncoded(); final String privateKeyAsBase64String = Base64.encodeBase64String(encoded); return privateKeyAsBase64String; } /** * Generate the corresponding {@link PublicKey} object from the given {@link PrivateKey} object. * * @param privateKey * the private key * @return the corresponding {@link PublicKey} object or null if generation failed. * @throws NoSuchAlgorithmException * the no such algorithm exception * @throws InvalidKeySpecException * the invalid key spec exception */ public static PublicKey generatePublicKey(final PrivateKey privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException { if (privateKey instanceof RSAPrivateKey) { final RSAPrivateCrtKey privk = (RSAPrivateCrtKey) privateKey; final RSAPublicKeySpec publicKeySpec = new RSAPublicKeySpec(privk.getModulus(), privk.getPublicExponent()); final KeyFactory keyFactory = KeyFactory.getInstance(KeyPairGeneratorAlgorithm.RSA.getAlgorithm()); final PublicKey publicKey = keyFactory.generatePublic(publicKeySpec); return publicKey; } return null; } }