using System.Text;

using System.Security.Cryptography;

using System;

using UnityEngine;

public class KeyGenerator

{

//key1 is fixed key

//key2 is user key

public static byte[] MakeKeyBytes(string fixedKey, string userKey, int userKeylength = 4)

{

byte[] key = new byte[16] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

byte[] fixedKeyBytes = Encoding.ASCII.GetBytes(fixedKey);

byte[] userKeyBytes = Encoding.ASCII.GetBytes(userKey);

byte[] hash = GetKeyHash(userKeyBytes);

for (int i = 0; i < fixedKeyBytes.Length; ++i)

key[i] = fixedKeyBytes[i];

if (userKeylength > 0)

{

for (int i = (16 - userKeylength), j = 0; i < key.Length; ++i, ++j)

{

if (j < userKeyBytes.Length)

key[i] = userKeyBytes[j] ^= hash[j];

else

key[i] = hash[j];

}

}

return key;

}

public static byte[] GetKeyHash(byte[] key, string salt = null)

{

SHA256 sha256 = SHA256.Create();

byte[] hash = sha256.ComputeHash(key);

if (salt == null)

{

return hash;

}

byte[] saltBytes = Encoding.ASCII.GetBytes(salt);

for(int i = 0; i < hash.Length; ++i)

hash[i] ^= saltBytes[i % saltBytes.Length];

return hash;

}

public static byte[] GetHash(int data)

{

SHA256 sha256 = SHA256.Create();

byte[] bytes = BitConverter.GetBytes(data);

byte[] hash = sha256.ComputeHash(bytes);

return hash;

}

public static string GenerateRandomString(int length)

{

const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()_-+=|\\/?.>,<~`\'\" ";

StringBuilder builder = new StringBuilder();

System.Random random = new System.Random();

for (int i = 0; i < length; i++)

{

int index = random.Next(chars.Length);

builder.Append(chars[index]);

}

return builder.ToString();

}

}