C# 产生真随机数（RNGCryptoServiceProvider）

作者：代码星球 发布时间：2023-04-16 阅读：0

public static string Generate(string dictionary, int length)
{
    string result = "";

    RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();

    byte[] data = new byte[8];
    int max = dictionary.Length - 1;
    for (int i = 0; i < length; i++)
    {
        rng.GetBytes(data);
        int rnd = (int)Math.Round(Math.Abs(BitConverter.ToInt64(data, 0)) / (decimal)long.MaxValue * max, 0);

        result += dictionary.Substring(rnd, 1);
    }

    return result;
}

RNGCryptoServiceProvider

命名空间: System.Security.Cryptography

程序集: mscorlib（位于 mscorlib.dll）

关于伪随机数，请参见：到底要不要用伪随机数？

微软有自带产生密码的（System.Web.Security.Membership.GeneratePassword），当然也是用到了随机数，它是怎样的呢？其源代码如下：

// System.Web.Security.Membership
public static string GeneratePassword(int length, int numberOfNonAlphanumericCharacters)
{
	if (length < 1 || length > 128)
	{
		throw new ArgumentException(SR.GetString("Membership_password_length_incorrect"));
	}
	if (numberOfNonAlphanumericCharacters > length || numberOfNonAlphanumericCharacters < 0)
	{
		throw new ArgumentException(SR.GetString("Membership_min_required_non_alphanumeric_characters_incorrect", new object[]
		{
			"numberOfNonAlphanumericCharacters"
		}));
	}
	string text;
	int num4;
	do
	{
		byte[] array = new byte[length];
		char[] array2 = new char[length];
		int num = 0;
		new RNGCryptoServiceProvider().GetBytes(array);
		for (int i = 0; i < length; i++)
		{
			int num2 = (int)(array[i] % 87);
			if (num2 < 10)
			{
				array2[i] = (char)(48 + num2);
			}
			else
			{
				if (num2 < 36)
				{
					array2[i] = (char)(65 + num2 - 10);
				}
				else
				{
					if (num2 < 62)
					{
						array2[i] = (char)(97 + num2 - 36);
					}
					else
					{
						array2[i] = Membership.punctuations[num2 - 62];
						num++;
					}
				}
			}
		}
		if (num < numberOfNonAlphanumericCharacters)
		{
			Random random = new Random();
			for (int j = 0; j < numberOfNonAlphanumericCharacters - num; j++)
			{
				int num3;
				do
				{
					num3 = random.Next(0, length);
				}
				while (!char.IsLetterOrDigit(array2[num3]));
				array2[num3] = Membership.punctuations[random.Next(0, Membership.punctuations.Length)];
			}
		}
		text = new string(array2);
	}
	while (CrossSiteScriptingValidation.IsDangerousString(text, out num4));
	return text;
}

本文标签：产生随机数 RNGCryptoServiceProvider

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C# 产生真随机数（RNGCryptoServiceProvider）

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