/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.shiro.crypto;
import org.apache.shiro.util.ByteSource;
import org.apache.shiro.util.SimpleByteSource;
import java.security.SecureRandom;
/**
* Default implementation of the {@link RandomNumberGenerator RandomNumberGenerator} interface, backed by a
* {@link SecureRandom SecureRandom} instance.
* <p/>
* This class is a little easier to use than using the JDK's {@code SecureRandom} class directly. It also
* allows for JavaBeans-style of customization, convenient for Shiro's INI configuration or other IoC configuration
* mechanism.
*
* @since 1.1
*/
public class SecureRandomNumberGenerator implements RandomNumberGenerator {
protected static final int DEFAULT_NEXT_BYTES_SIZE = 128;
private int defaultNextBytesSize;
private SecureRandom secureRandom;
/**
* Creates a new instance with a default backing {@link SecureRandom SecureRandom} and a
* {@link #getDefaultNextBytesSize() defaultNextBytesSize} of {@code 128}.
*/
public SecureRandomNumberGenerator() {
this.defaultNextBytesSize = DEFAULT_NEXT_BYTES_SIZE;
this.secureRandom = new SecureRandom();
}
/**
* Seeds the backing {@link SecureRandom SecureRandom} instance with additional seed data.
*
* @param bytes the seed bytes
* @see SecureRandom#setSeed(byte[])
*/
public void setSeed(byte[] bytes) {
this.secureRandom.setSeed(bytes);
}
/**
* Returns the {@link SecureRandom SecureRandom} backing this instance.
*
* @return the {@link SecureRandom SecureRandom} backing this instance.
*/
public SecureRandom getSecureRandom() {
return secureRandom;
}
/**
* Sets the {@link SecureRandom SecureRandom} to back this instance.
*
* @param random the {@link SecureRandom SecureRandom} to back this instance.
* @throws NullPointerException if the method argument is null
*/
public void setSecureRandom(SecureRandom random) throws NullPointerException {
if (random == null) {
throw new NullPointerException("SecureRandom argument cannot be null.");
}
this.secureRandom = random;
}
/**
* Returns the size of the generated byte array for calls to {@link #nextBytes() nextBytes()}. Defaults to
* {@code 128}, a commonly used number in cryptographic algorithms.
*
* @return the size of the generated byte array for calls to {@link #nextBytes() nextBytes()}.
*/
public int getDefaultNextBytesSize() {
return defaultNextBytesSize;
}
/**
* Sets the size of the generated byte array for calls to {@link #nextBytes() nextBytes()}. Defaults to
* {@code 128}, a commonly used number in cryptographic algorithms.
*
* @param defaultNextBytesSize the size of the generated byte array for calls to {@link #nextBytes() nextBytes()}.
* @throws IllegalArgumentException if the argument is 0 or negative
*/
public void setDefaultNextBytesSize(int defaultNextBytesSize) throws IllegalArgumentException {
if ( defaultNextBytesSize <= 0) {
throw new IllegalArgumentException("size value must be a positive integer (1 or larger)");
}
this.defaultNextBytesSize = defaultNextBytesSize;
}
public ByteSource nextBytes() {
return nextBytes(getDefaultNextBytesSize());
}
public ByteSource nextBytes(int numBytes) {
if (numBytes <= 0) {
throw new IllegalArgumentException("numBytes argument must be a positive integer (1 or larger)");
}
byte[] bytes = new byte[numBytes];
this.secureRandom.nextBytes(bytes);
return new SimpleByteSource(bytes);
}
}