
El Advanced Encryption Standard (AES), también conocido como Rijndael Encryption, fue desarrollado por dos criptógrafos belgas, Vincent Rijmen y Joan Daemen. AES ofrece una función para compartir o almacenar sus archivos de manera altamente segura. En este blog no hablamos de criptografía o AES, solo explica cómo cifrar y descifrar una cadena usando AES.
En el sistema de cifrado .Net Rijndael (Clase RijndaelManaged) es parte de la criptografía (System.Security.Cryptography). Esta clase nos permite cifrar y descifrar contraseñas o cualquier cadena de texto que quieran cifrar en c#.
public class SecurityManager
{
static readonly string password = "P455W0rd";
public static string Encrypt(string plainText)
{
if (plainText == null)
{
return null;
}
// Get the bytes of the string
var bytesToBeEncrypted = Encoding.UTF8.GetBytes(plainText);
var passwordBytes = Encoding.UTF8.GetBytes(password);
// Hash the password with SHA256
passwordBytes = SHA512.Create().ComputeHash(passwordBytes);
var bytesEncrypted = Encrypt(bytesToBeEncrypted, passwordBytes);
return Convert.ToBase64String(bytesEncrypted);
}
/// <summary>
/// Decrypt a string.
/// </summary>
/// <param name="encryptedText">String to be decrypted</param>
/// <exception cref="FormatException"></exception>
public static string Decrypt(string encryptedText)
{
if (encryptedText == null)
{
return null;
}
// Get the bytes of the string
var bytesToBeDecrypted = Convert.FromBase64String(encryptedText);
var passwordBytes = Encoding.UTF8.GetBytes(password);
passwordBytes = SHA512.Create().ComputeHash(passwordBytes);
var bytesDecrypted = Decrypt(bytesToBeDecrypted, passwordBytes);
return Encoding.UTF8.GetString(bytesDecrypted);
}
private static byte[] Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = null;
var saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.KeySize = 256;
AES.BlockSize = 128;
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}
private static byte[] Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
{
byte[] decryptedBytes = null;
var saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.KeySize = 256;
AES.BlockSize = 128;
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
cs.Close();
}
decryptedBytes = ms.ToArray();
}
}
return decryptedBytes;
}
}