“Padding is invalid and cannot be removed” using AesManaged - windows-phone-8

Question

I am getting error "Padding is invalid and cannot be removed."
when trying to decrypt file contents in chunks(using buffer). I am able to decrypt whole file at once but not in blocks. I found many links regarding this problem and most of them suggested to set Padding of AesManaged object
like aesManaged.Padding = PaddingMode.None
But this property is not available in window phone application.
Below is method:
internal static byte[] DecryptBytes(byte[] cipherText, string password)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
byte[] decryptedBytes= new byte[cipherText.Length];
using (var rijAlg = new AesManaged { KeySize = 256, BlockSize = 128 })
{
var key = new Rfc2898DeriveBytes(password, Encoding.UTF8.GetBytes(Salt));
rijAlg.Key = key.GetBytes(rijAlg.KeySize / 8);
rijAlg.IV = key.GetBytes(rijAlg.BlockSize / 8);
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for decryption.
using (var msDecrypt = new MemoryStream())
{
using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Write))
{
csDecrypt.Write(cipherText, 0, cipherText.Length);
csDecrypt.FlushFinalBlock();
}
decryptedBytes = msDecrypt.ToArray();
}
}
return decryptedBytes;
}
Please suggest issue in above code or any other workaround

Answer 1

Don't use aesManaged.Padding = PaddingMode.None it will only hide the error, not solve it. You would get the error for incorrectly derived keys, incorrect ciphertext or - for smaller ciphertext - incorrect IV.
Print out the values of all the inputs in hexadecimals right before you perform the decrypt, then compare them with the ones obtained for encryption.