SecureRandomUtils.java

/*
 * BSD 2-Clause License
 * 
 * Copyright (c) 2022, [Aleksandra Serba, Marcin Czerniak, Bartosz Wawrzyniak, Adrian Antkowiak]
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package dev.vernite.vernite.common.utils;

import java.security.SecureRandom;

import lombok.AccessLevel;
import lombok.NoArgsConstructor;

/**
 * Utils for common secure random operations.
 */
@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class SecureRandomUtils {

    private static final SecureRandom RANDOM = new SecureRandom();

    private static final char[] CHARS = "0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM".toCharArray();

    /**
     * Generates a secure random string of the given length.
     * 
     * @param length must be greater than 0
     * @return the generated string
     */
    public static String generateSecureRandomString(int length) {
        var secureCharacters = new char[length];

        for (var index = 0; index < secureCharacters.length; index++) {
            secureCharacters[index] = CHARS[RANDOM.nextInt(CHARS.length)];
        }

        return new String(secureCharacters);
    }

    /**
     * Generates a secure random string of length 128.
     * 
     * @return the generated string
     */
    public static String generateSecureRandomString() {
        return generateSecureRandomString(128);
    }

}