using System.Security.Cryptography;
string senha = "/HxNCjIzAxuRzW3plGYuvR8EcFSm/m5aciXXSX+03vU=";
var fullCipher = Convert.FromBase64String(senha);
var cipher = new byte[fullCipher.Length - iv.Length];
Buffer.BlockCopy(fullCipher, 0, iv, 0, iv.Length);
Buffer.BlockCopy(fullCipher, iv.Length, cipher, 0, cipher.Length);
var key = Encoding.UTF8.GetBytes("CHAVE_154858_OKIUI_7458_IKJKI_32");
using (var aesAlg = Aes.Create())
using (var decryptor = aesAlg.CreateDecryptor(key, iv))
using (var msDecrypt = new MemoryStream(cipher))
using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
using (var srDecrypt = new StreamReader(csDecrypt))
result = srDecrypt.ReadToEnd();
Console.WriteLine("Fala Navi");
Console.WriteLine("A senha é: " + result);