using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace PEP_Tool
{
    internal class Crypto
    {
        public static byte[] GetHashKey(string hashKey, string Salt = "D99CFBD250C45D34B954C74E2054A282")
        {
            // Initialize
            UTF8Encoding encoder = new UTF8Encoding();
            // Get the salt
            string salt = !string.IsNullOrEmpty(Salt) ? Salt : "I am a nice little salt";
            byte[] saltBytes = encoder.GetBytes(salt);
            // Setup the hasher
            Rfc2898DeriveBytes rfc = new Rfc2898DeriveBytes(hashKey, saltBytes);
            // Return the key
            return rfc.GetBytes(16);
        }
        public static string Decrypt(byte[] key, string encryptedString)
        {
            // Initialize
            AesManaged decryptor = new AesManaged();
            byte[] encryptedData = Convert.FromBase64String(encryptedString);
            // Set the key
            decryptor.Key = key;
            decryptor.IV = key;
            // create a memory stream
            using (MemoryStream decryptionStream = new MemoryStream())
            {
                // Create the crypto stream
                using (CryptoStream decrypt = new CryptoStream(decryptionStream, decryptor.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    // Encrypt
                    decrypt.Write(encryptedData, 0, encryptedData.Length);
                    decrypt.Flush();
                    decrypt.Close();
                    // Return the unencrypted data
                    byte[] decryptedData = decryptionStream.ToArray();
                    return UTF8Encoding.UTF8.GetString(decryptedData, 0, decryptedData.Length);
                }
            }
        }
    }
}