org.springframework.security.core.token.SecureRandomFactoryBean Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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.core.token;
import java.io.InputStream;
import java.security.SecureRandom;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
import org.springframework.util.FileCopyUtils;
/**
* Creates a {@link SecureRandom} instance.
*
* @author Ben Alex
* @since 2.0.1
*/
public class SecureRandomFactoryBean implements FactoryBean {
private String algorithm = "SHA1PRNG";
private Resource seed;
@Override
public SecureRandom getObject() throws Exception {
SecureRandom random = SecureRandom.getInstance(this.algorithm);
// Request the next bytes, thus eagerly incurring the expense of default
// seeding and to prevent the see from replacing the entire state
random.nextBytes(new byte[1]);
if (this.seed != null) {
// Seed specified, so use it
byte[] seedBytes = FileCopyUtils.copyToByteArray(this.seed.getInputStream());
random.setSeed(seedBytes);
}
return random;
}
@Override
public Class getObjectType() {
return SecureRandom.class;
}
@Override
public boolean isSingleton() {
return false;
}
/**
* Allows the Pseudo Random Number Generator (PRNG) algorithm to be nominated.
* Defaults to "SHA1PRNG".
* @param algorithm to use (mandatory)
*/
public void setAlgorithm(String algorithm) {
Assert.hasText(algorithm, "Algorithm required");
this.algorithm = algorithm;
}
/**
* Allows the user to specify a resource which will act as a seed for the
* {@link SecureRandom} instance. Specifically, the resource will be read into an
* {@link InputStream} and those bytes presented to the
* {@link SecureRandom#setSeed(byte[])} method. Note that this will simply supplement,
* rather than replace, the existing seed. As such, it is always safe to set a seed
* using this method (it never reduces randomness).
* @param seed to use, or null if no additional seeding is needed
*/
public void setSeed(Resource seed) {
this.seed = seed;
}
}