两个值之间的加密安全随机整数

Question

我一直在使用RNGCryptoServiceProvider 创建一个随机整数。这将在整数的上下限之间生成一个随机整数。

private static RNGCryptoServiceProvider rngCryptoServiceProvider = new RNGCryptoServiceProvider();

public int Execute(int lowerBound, int upperBound)
{
    // initialize an array of bytes equal to the number of bytes in an integer
    var numberOfBytes = sizeof(int);
    var bytes = new byte[numberOfBytes];

    // fill the array with random bytes
    rngCryptoServiceProvider.GetBytes(bytes);

    // convert the byte array to an integer
    var bitsAsInteger = BitConverter.ToInt32(bytes, 0);
    
    return bitsAsInteger;
}

现在我想在两个整数之间生成一个随机整数。根据我的阅读，这不是一项微不足道的任务。所以，我想我可以随机播种System.Random 类并使用Next() 功能来进行数学运算。这是一个明智的做法吗？

private static RNGCryptoServiceProvider rngCryptoServiceProvider = new RNGCryptoServiceProvider();

public int Execute(int lowerBound, int upperBound)
{
    // initialize an array of bytes equal to the number of bytes in an integer
    var numberOfBytes = sizeof(int);
    var bytes = new byte[numberOfBytes];

    // fill the array with random bytes
    rngCryptoServiceProvider.GetBytes(bytes);

    // convert the byte array to an integer
    var bitsAsInteger = BitConverter.ToInt32(bytes, 0);

    // use the random integer to seed the non cryptographically secure Random class
    var random = new System.Random(bitsAsInteger);
    
    // use the Next() functionality to do the math to get a random number between two values
    var randomInteger = random.Next(lowerBound, upperBound);
    
    return randomInteger;
}

有没有其他方法可以在不使用System.Random 的情况下达到相同的结果？

Answer 1

你可以使用模数。

private static RNGCryptoServiceProvider rngCryptoServiceProvider = new RNGCryptoServiceProvider();

public int Execute(int lowerBound, int upperBound)
{
    // initialize an array of bytes equal to the number of bytes in an integer
    var numberOfBytes = sizeof(int);
    var bytes = new byte[numberOfBytes];

    // fill the array with random bytes
    rngCryptoServiceProvider.GetBytes(bytes);

    // convert the byte array to an integer
    var bitsAsInteger = BitConverter.ToInt32(bytes, 0);
    var m = (int)(Math.Abs(bitsAsInteger) % ((long)int.MaxValue - int.MinValue));
    return m + lowerBound;
}