using System;

using System.IO;

using System.Security.Cryptography;

using System.Threading.Tasks;

​

/// <summary>

/// Serviço responsável por encriptar/descriptar valores através do algoritmo AES-256-CBC

/// </summary>

public class AesCryptographer

{

    private readonly string _key;

​

    public AesCryptographer(string key)

    {

        _key = key;

    }

​

    public async Task<string> Decrypt(string encryptedValue)

    {

        try

        {

            using var rijndael = FactoryRijndael(_key);

            using var memoryStream = new MemoryStream(Convert.FromBase64String(encryptedValue));

            using var cryptoStream = new CryptoStream(memoryStream, rijndael.CreateDecryptor(), CryptoStreamMode.Read);

            using var streamReader = new StreamReader(cryptoStream);

​

            return await streamReader.ReadToEndAsync();

        }

        catch (Exception ex)

        {

            Console.WriteLine("An AES cryptographic error occurred: "+ ex.Message);

            throw;

        }

    }

​

    public async Task<string> Encrypt(string value, string key = null)

    {

        try

        {

            using (var rijndael = FactoryRijndael(_key)) 

            {

                using (var memoryStream = new MemoryStream())

                {

                    using (var cryptoStream = new CryptoStream(memoryStream, rijndael.CreateEncryptor(), CryptoStreamMode.Write))

                    {

                        using (var streamWriter = new StreamWriter(cryptoStream)) 

                        {

                            await streamWriter.WriteAsync(value);

                        }

                    }

​

                    return Convert.ToBase64String(memoryStream.ToArray());

                }

            }

        }

        catch (Exception ex)

        {

            Console.WriteLine("An AES cryptographic error occurred: "+ ex.Message);

            throw;

        }

    }

​

    private static RijndaelManaged FactoryRijndael(string key)

    {

        return new RijndaelManaged { 

            Key = Convert.FromBase64String(key), 

            IV = new byte[16], 

            Mode = CipherMode.CBC 

        };  

    }

}

​

public class Program

{

    public static void Main()

    {

        var key = "MTIzNDU2Nzg5MDEyMzQ1NjEyMzQ1Njc4OTAxMjM0NTY=";

        var aesCryptographer = new AesCryptographer(key);   

        Console.WriteLine("Escreva o conteudo a ser criptografado:");

        string valueToEncrypt = @Console.ReadLine();

        Console.WriteLine("Valor criptografado");

        Console.WriteLine(aesCryptographer.Encrypt(valueToEncrypt).GetAwaiter().GetResult());

    }

}