com.password4j.SaltGenerator Maven / Gradle / Ivy
/*
* (C) Copyright 2020 Password4j (http://password4j.com/).
*
* 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 com.password4j;
import java.security.SecureRandom;
/**
* This class contains static functions that
* help to create a secure salt.
*
* In cryptography, a salt is random data that is used as
* an additional input to a CHF.
*
* @author David Bertoldi
* @since 0.1.0
*/
public class SaltGenerator
{
private SaltGenerator()
{
//
}
/**
* Generates an array of {@code byte}s that can be used
* as salt by the CHFs.
* The generated salt is created by a cryptographically
* strong random number generator (RNG).
*
* The parameter length must be a non-negative number,
* otherwise a {@link BadParametersException} is thrown.
*
* @param length of the returned byte array
* @return a salt as array of {@code byte}s
* @throws BadParametersException if the length is negative
* @since 0.1.0
*/
public static byte[] generate(int length)
{
if (length < 0)
{
throw new BadParametersException("Salt length cannot be negative");
}
byte[] salt = new byte[length];
SecureRandom sr = AlgorithmFinder.getSecureRandom();
sr.nextBytes(salt);
return salt;
}
/**
* Generates an array of {@code byte}s that can be used
* as salt by the CHFs.
* The generated salt is created by a cryptographically
* strong random number generator (RNG).
*
* The length of the array is 64.
*
* @return a salt as array of {@code byte}s
* @since 0.1.0
*/
public static byte[] generate()
{
return generate(64);
}
}