pl.kotcrab.crypto.CryptoUtils.java Source code

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Here is the source code for pl.kotcrab.crypto.CryptoUtils.java

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/*******************************************************************************
 * Copyright 2014 Pawel Pastuszak
 *
 * 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
 *
 * http://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 pl.kotcrab.crypto;

import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.KeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

/** Provides various cryptographic methods.
 * @author Pawel Pastuszak */
public class CryptoUtils {

    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    private static SecureRandom random;

    private static final int MAX_BYTES_BEFORE_RESEED = 100000;
    private static int bytesTaken = 0;

    static {
        random = getSecureRandom();
    }

    /** Constructs and returns secure random. Algorithm depends on operating system, on Windows SHA1PRNG from Sun will be used and on
     * Unix and Mac systems NativePRNG will be used.
     * @return SecureRandom instance */
    public static SecureRandom getSecureRandom() {
        try {
            if (OSDetector.isUnix() || OSDetector.isMac())
                return SecureRandom.getInstance("NativePRNG", "SUN");
            else
                return SecureRandom.getInstance("SHA1PRNG", "SUN");
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }

        return null;
    }

    private static void reseedRandomIfNeeded() {
        if (bytesTaken >= MAX_BYTES_BEFORE_RESEED) {
            random = getSecureRandom();
            bytesTaken = 0;
        }
    }

    /** Generates random 16 bytes
     * @return random 16 bytes */
    public static byte[] getRandomBytes16() {
        bytesTaken += 16;
        byte[] salt = new byte[16];
        random.nextBytes(salt);
        reseedRandomIfNeeded();
        return salt;
    }

    /** Generates PublicKey from encoded bytes of X509EncodedKeySpec. Bytes must be in Base64 string.
     * @param base64 Key from encoded bytes of {@link X509EncodedKeySpec#getEncoded()}. Encoded in Base64 string.
     * @return created public key */
    public static PublicKey getRSAPublicKeyFromString64(String base64) {
        try {
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.decodeBase64(base64));
            KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
            return keyFactory.generatePublic(keySpec);
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }

        return null;
    }

    /** Generates AES key from provided password and salt. Used algorithm is PBKDF2WithHmacSHA1.
     * @param password password in char array, using {@link CryptoUtils#fillZeros(char[])} is recommend after generating key
     * @param salt salt for this key
     * @return SecretKeySpec */
    public static SecretKeySpec getAESKeyFromPassword(char[] password, byte[] salt) {
        try {
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
            KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
            return new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }

        return null;
    }

    /** Returns AES SecretKey from provided encoded bytes.
     * 
     * @param encoded encoded bytes of SecretKeySpec
     * @return SecretKey */
    public static SecretKey getAESKeyFromEncoded(byte[] encoded) {
        return new SecretKeySpec(encoded, 0, encoded.length, "AES");
    }

    /** Generates random AES key
     * @return random AES key */
    public static SecretKey getAESRandomKey() {
        try {
            KeyGenerator keyGen = KeyGenerator.getInstance("AES", "BC");
            keyGen.init(256);
            return keyGen.generateKey();
        } catch (NoSuchAlgorithmException | NoSuchProviderException e) {
            e.printStackTrace();
        }

        return null;
    }

    /** Fills zeros in provided char array, useful for clearing arrays with passwords
     * @param array array to be cleared */
    public static void fillZeros(char[] array) {
        for (int i = 0; i < array.length; i++)
            array[i] = 0;
    }
}