CODEWITHSUNDEEP
c#
CoronaVirus
CoronaVirus

Reputation: 421

Length of the data to Encrypt is invalid

Getting Exception " length of the data to ENCRYPTION is invalid". 

private static readonly byte[] salt = Encoding.ASCII.GetBytes("S@sh@kt@ VMS");

public static string Encrypt(string textToEncrypt, string encryptionPassword)
{
    byte[] encryptedBytes = null;
    try
    {
        var algorithm = GetAlgorithm(encryptionPassword);
        algorithm.Padding = PaddingMode.None;
        using (ICryptoTransform encryptor = algorithm.CreateEncryptor(algorithm.Key, algorithm.IV))
        {
            byte[] bytesToEncrypt = Encoding.UTF8.GetBytes(textToEncrypt);
            encryptedBytes = InMemoryCrypt(bytesToEncrypt, encryptor);
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
    return Convert.ToBase64String(encryptedBytes);
}

 // Performs an in-memory encrypt/decrypt transformation on a byte array.

private static byte[] InMemoryCrypt(byte[] data, ICryptoTransform transform)
{
    MemoryStream memory = new MemoryStream();
    using (Stream stream = new CryptoStream(memory, transform, CryptoStreamMode.Write))
    {
        stream.Flush();
        stream.Write(data, 0, data.Length);
        //stream.FlushFinalBlock();
    }
    return memory.ToArray();
}

private static RijndaelManaged GetAlgorithm(string encryptionPassword)
{
    // Create an encryption key from the encryptionPassword and salt.
    var key = new Rfc2898DeriveBytes(encryptionPassword, salt);
    // Declare that we are going to use the Rijndael algorithm with the key that we've just got.
    var algorithm = new RijndaelManaged();
    int bytesForKey = algorithm.KeySize/8;
    int bytesForIV = algorithm.BlockSize/8;
    algorithm.Key = key.GetBytes(bytesForKey);
    algorithm.IV = key.GetBytes(bytesForIV);
    return algorithm;
}

And the decryption routine is:

public static string Decrypt(string encryptedText, string encryptionPassword)
{
    var algorithm = GetAlgorithm(encryptionPassword);
    algorithm.Padding = PaddingMode.PKCS7; 
    byte[] descryptedBytes;
    using (ICryptoTransform decryptor = algorithm.CreateDecryptor(algorithm.Key, algorithm.IV))
    {
        byte[] encryptedBytes = Convert.FromBase64String(encryptedText);
        descryptedBytes = InMemoryCrypt(encryptedBytes, decryptor);
    } 
    return Encoding.UTF8.GetString(descryptedBytes); 
}

Upvotes: 1

Views: 7833

Answers (1)

CodesInChaos
CodesInChaos

Reputation: 108800

PaddingMode.None requires that the input is a multiple of the block size. Use somethink like PaddingMode.PKCS7 instread.

A few other issues with your code:

  1. A constant doesn't make a good salt
  2. The constant salt together with deterministic derivation of the IV from the password means that you're reusing (Key, IV) pairs, which should not be done
  3. You don't add authentication/some kind of MAC. That often leads to padding oracles or similar attacks
  4. You read more the native size from the PBKDF2 output. That halves your key derivation speed without slowing down an attacker.

Upvotes: 6

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