How to make a game securised with highscore in database

You can encrypt the data that you submit to database : I have already created an encryption system that you can use simply :

 using System;
 using System.Text;
 using System.Security.Cryptography;
 using System.IO;
 using System.Linq;
 
 namespace Efencryptor
 {
     public static class Efencryptor
     {
         // This constant is used to determine the keysize of the encryption algorithm in bits.
         // We divide this by 8 within the code below to get the equivalent number of bytes.
         private const int Keysize = 256;
 
         // This constant determines the number of iterations for the password bytes generation function.
         private const int DerivationIterations = 1000;
 
         public static string Encrypt(string plainText, string passPhrase)
         {
             // Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
             // so that the same Salt and IV values can be used when decrypting.  
             var saltStringBytes = Generate256BitsOfRandomEntropy();
             var ivStringBytes = Generate256BitsOfRandomEntropy();
             var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
             Rfc2898DeriveBytes password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations);
             try
             {
                 var keyBytes = password.GetBytes(Keysize / 8);
                 using (var symmetricKey = new RijndaelManaged())
                 {
                     symmetricKey.BlockSize = 256;
                     symmetricKey.Mode = CipherMode.CBC;
                     symmetricKey.Padding = PaddingMode.PKCS7;
                     using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes))
                     {
                         using (var memoryStream = new MemoryStream())
                         {
                             using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                             {
                                 cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                                 cryptoStream.FlushFinalBlock();
                                 // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
                                 var cipherTextBytes = saltStringBytes;
                                 cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
                                 cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
                                 memoryStream.Close();
                                 cryptoStream.Close();
                                 return Convert.ToBase64String(cipherTextBytes);
                             }
                         }
                     }
                 }
             }
             catch
             {
                 return plainText;
             }
         }
 
         public static string Decrypt(string cipherText, string passPhrase)
         {
             // Get the complete stream of bytes that represent:
             // [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
             var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
             // Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
             var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
             // Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
             var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
             // Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
             var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();
 
 
             var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations);
             try
             {
                 var keyBytes = password.GetBytes(Keysize / 8);
                 using (var symmetricKey = new RijndaelManaged())
                 {
                     symmetricKey.BlockSize = 256;
                     symmetricKey.Mode = CipherMode.CBC;
                     symmetricKey.Padding = PaddingMode.PKCS7;
                     using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
                     {
                         using (var memoryStream = new MemoryStream(cipherTextBytes))
                         {
                             using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                             {
                                 var plainTextBytes = new byte[cipherTextBytes.Length];
                                 var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                                 memoryStream.Close();
                                 cryptoStream.Close();
                                 return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
                             }
                         }
                     }
                 }
             }
             catch
             {
                 return cipherText;
             }
         }
 
         private static byte[] Generate256BitsOfRandomEntropy()
         {
             var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
             var rngCsp = new RNGCryptoServiceProvider();
                 // Fill the array with cryptographically secure random bytes.
                 rngCsp.GetBytes(randomBytes);
             return randomBytes;
         }
     }
 }

You can easily call the methods like :

 using Efencryptor;
 class Example {
     //whatever you want
     protected readonly string mypassword = "1234513454dfahda5853ag8f3fsdhfaj3542,265";
     void Main()
     {
         string data = "1565435";
         string encrypted = Efencryptor.Encrypt(data,mypassword);
         string decrypted = Efencryptor.Decrypt(encrypted, mypassword);
     }
 
 }

But what is someone decompile the script and find the method to encrypt there score ?