AES 64密钥生成

Question

I am trying to generate 64 HEX digits to be used as a AES 256 key with no success. Can somebody point out the mistakes and a better way to generate the same.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Security.Cryptography;

namespace Test
{
    public class Program
    {
        static System.Text.StringBuilder builder = new System.Text.StringBuilder();
        public static void Main(string[] args)
        {
            String randomNumber = Convert.ToBase64String (GenerateRandomNumber(32));
            Console.WriteLine(randomNumber);

           string input = randomNumber;
            char[] values = input.ToCharArray();
            foreach (char letter in values)
            {
                // Get the integral value of the character.
                int value = Convert.ToInt32(letter);
                // Convert the decimal value to a hexadecimal value in string form.
                string hexOutput = String.Format("{0:X}", value);
                // Console.WriteLine("Hexadecimal value of {0} is {1}", letter, hexOutput);
                builder.Append(hexOutput);
            }

            Console.WriteLine(builder);
        }


        public static byte[] GenerateRandomNumber(int length)
        {
            using (var randomNumberGenerator = new RNGCryptoServiceProvider())
            {
                var randomNumber = new byte[length];
                randomNumberGenerator.GetBytes(randomNumber);
                return randomNumber;
            }
        }
    }
}

Answer 1

I don't see why you need to convert it to a base64 string first. It could be as simple as this:

public class Program
{
    public static void Main(string[] args)
    {
        var key = GenerateRandomNumber(32);
        var hexEncodedKey = BitConverter.ToString(key).Replace("-", "");
        Console.WriteLine(hexEncodedKey);
    }

    public static byte[] GenerateRandomNumber(int length)
    {
        using (var randomNumberGenerator = RandomNumberGenerator.Create())
        {
            var randomNumber = new byte[length];
            randomNumberGenerator.GetBytes(randomNumber);
            return randomNumber;
        }
    }
}

Answer 2

Your biggest technical problem is that you used {0:X} when you meant {0:X2} . If the value is 10 the former produces "A" and the latter "0A". Since you've lost where all of the interior zeroes are your number isn't recoverable.

internal static string ByteArrayToHex(this byte[] bytes)
{
    StringBuilder builder = new StringBuilder(bytes.Length * 2);

    foreach (byte b in bytes)
    {
        builder.Append(b.ToString("X2"));
    }

    return builder.ToString();
}

(Code copied from https://github.com/dotnet/corefx/blob/7cad8486cbabbce0236bdf530e30db7036335524/src/Common/tests/System/Security/Cryptography/ByteUtils.cs#L37-L47 )

But it's also pretty unclear why you're rerouting through Base64+ToCharArray+ToInt32. You're replacing values in the 0-255 range (bytes) with values in the [A-Za-z0-9/=+] rangeset, equivalent to 0-63 (Base64 and all); so you a) wouldn't have a very random key and b) it'll be too long.

Answer 3

.NET框架已经具有用于生成对称密钥的方法Aes.GenerateKey（），请查看此MSDN文档： Aes类