Tengo algún texto, encriptado por AesManaged de C #, que debe ser descifrado en una aplicación de WinRT Metro. No puedo cambiar el código de cifrado, ya que el código tiene otras dependencias que no se pueden cambiar.

La función de cifrado se ve así:

// Note: Edited out possibly real password and salt:
Guid password = Guid.Parse("AAAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA");
Guid salt = Guid.Parse("AAAAAAAAA-BBBB-BBBB-BBBB-AAAAAAAAAAAA");

string EncryptedValue(string data)
{   
byte[] passwordBytes = password.ToByteArray();
byte[] saltBytes = salt.ToByteArray();

byte[] bKey = new byte[16];
for(int i = 0; i < 16; i++)
{
    bKey[i] = passwordBytes[i];
}

string encryptedData = String.Empty;
using (System.Security.Cryptography.AesManaged aesAlg = new System.Security.Cryptography.AesManaged())
{
    aesAlg.Key = bKey;
    aesAlg.IV = saltBytes;

    // Create a decrytor to perform the stream transform.
    System.Security.Cryptography.ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

    // Create the streams used for encryption.
    using (MemoryStream msEncrypt = new MemoryStream())
    {
        using (System.Security.Cryptography.CryptoStream csEncrypt = new System.Security.Cryptography.CryptoStream(msEncrypt, encryptor, System.Security.Cryptography.CryptoStreamMode.Write))
        {
            using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
            {

                //Write all data to the stream.
                swEncrypt.Write(data);
            }

            encryptedData = Convert.ToBase64String(msEncrypt.ToArray());
        }
    }
}

return encryptedData;
}

Ejemplo de datos:

   // Decrypted value is: 2029
   var _id = EncryptedSettingsBase.Decrypt("ROSNJ1XnAozF7LC0wW8AOg==");

Leí el siguiente post:http://social.msdn.microsoft.com/Forums/en-US/winappswithcsharp/thread/7cfcc576-1c2c-4a50-a546-09a45d3ff41f que parece el mismo problema, sin embargo, no he podido hacer que su sugerencia funcione, ya que tengo la excepción: 'Error de datos (comprobación de redundancia cíclica). (Excepción de HRESULT: 0x80070017) '.

internal class EncryptedSettingsBase
{
    public static string Decrypt(string cipherText)
    {
        var passwordBytes = (new Guid("AAAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA")).ToByteArray();
        var salt = (new Guid("AAAAAAAAA-BBBB-AAAA-AAAA-AAAAAAAAAAAA")).ToString();

        byte[] bKey = new byte[16];
        for (int i = 0; i < 16; i++)
        {
            bKey[i] = passwordBytes[i];
        }

        IBuffer pwBuffer = CryptographicBuffer.CreateFromByteArray(bKey);
        IBuffer saltBuffer = CryptographicBuffer.ConvertStringToBinary(salt, BinaryStringEncoding.Utf16LE);
        IBuffer cipherBuffer = CryptographicBuffer.DecodeFromBase64String(cipherText);

        // Derive key material for password size 32 bytes for AES256 algorithm
        KeyDerivationAlgorithmProvider keyDerivationProvider = KeyDerivationAlgorithmProvider.OpenAlgorithm("PBKDF2_SHA1");
        // using salt and 1000 iterations
        KeyDerivationParameters pbkdf2Parms = KeyDerivationParameters.BuildForPbkdf2(saltBuffer, 1000);

        // create a key based on original key and derivation parmaters
        CryptographicKey keyOriginal = keyDerivationProvider.CreateKey(pwBuffer);
        IBuffer keyMaterial = CryptographicEngine.DeriveKeyMaterial(keyOriginal, pbkdf2Parms, 32);
        CryptographicKey derivedPwKey = keyDerivationProvider.CreateKey(pwBuffer);

        // derive buffer to be used for encryption salt from derived password key 
        IBuffer saltMaterial = CryptographicEngine.DeriveKeyMaterial(derivedPwKey, pbkdf2Parms, 16);

        // display the keys - because KeyDerivationProvider always gets cleared after each use, they are very similar unforunately
        string keyMaterialString = CryptographicBuffer.EncodeToBase64String(keyMaterial);
        string saltMaterialString = CryptographicBuffer.EncodeToBase64String(saltMaterial);

        SymmetricKeyAlgorithmProvider symProvider = SymmetricKeyAlgorithmProvider.OpenAlgorithm("AES_CBC_PKCS7");
        // create symmetric key from derived password material
        CryptographicKey symmKey = symProvider.CreateSymmetricKey(keyMaterial);

        // encrypt data buffer using symmetric key and derived salt material
        IBuffer resultBuffer = CryptographicEngine.Decrypt(symmKey, cipherBuffer, saltMaterial);
        string result = CryptographicBuffer.ConvertBinaryToString(BinaryStringEncoding.Utf16LE, resultBuffer);
        return result;
    }
}

Probablemente estoy haciendo algo tonto, pero no entiendo completamente estas cosas. Alguien sabe donde me voy mal?

Cualquier ayuda es muy apreciada.

Saludos, Jon