org.jasypt.iv.RandomIvGenerator Maven / Gradle / Ivy
/*
* =============================================================================
*
* Copyright (c) 2019, The JASYPT team (http://www.jasypt.org)
*
* 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 org.jasypt.iv;
import org.jasypt.exceptions.EncryptionInitializationException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
/**
*
* This implementation of {@link IvGenerator} holds a secure random
* generator which can be used for generating random initialization vectors (IV) for encryption.
*
*
* The algorithm used for random number generation can be configured at
* instantiation time. If not, the default algorithm will be used.
*
*
* This class is thread-safe.
*
*
* @since 1.9.3
*
* @author Hoki Torres
*
*/
public class RandomIvGenerator implements IvGenerator {
/**
* The default algorithm to be used for secure random number
* generation: set to SHA1PRNG.
*/
public static final String DEFAULT_SECURE_RANDOM_ALGORITHM = "SHA1PRNG";
private final SecureRandom random;
/**
* Creates a new instance of RandomIvGenerator using the
* default secure random number generation algorithm.
*/
public RandomIvGenerator() {
this(DEFAULT_SECURE_RANDOM_ALGORITHM);
}
/**
* Creates a new instance of RandomIvGenerator specifying a
* secure random number generation algorithm.
*/
public RandomIvGenerator(final String secureRandomAlgorithm) {
super();
try {
this.random = SecureRandom.getInstance(secureRandomAlgorithm);
} catch (NoSuchAlgorithmException e) {
throw new EncryptionInitializationException(e);
}
}
/**
* Generate a random IV of the specified length in bytes.
*
* @param lengthBytes length in bytes.
* @return the generated IV.
*/
public byte[] generateIv(final int lengthBytes) {
final byte[] iv = new byte[lengthBytes];
synchronized (this.random) {
this.random.nextBytes(iv);
}
return iv;
}
/**
* This IV generator needs the IV to be included unencrypted in
* encryption results, because of its being random. This method will always
* return true.
*
* @return true
*/
public boolean includePlainIvInEncryptionResults() {
return true;
}
}