Wrong size of the encrypted data (AES)

Question

I need to perform encryption array of byte []. I used the example available on the Microsoft. Unfortunately, the encrypted data is truncated to the size that is a multiple of 16. If, in the example of the data I will add 8 times byte 0, the data will be encrypted properly. Padding has been set, but I do not see anything to change it. How to solve this problem, the data do not become cut off.

public byte[] EncryptAES(byte[] plainBytes)
{
    System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();
    byte[] FKey = encoding.GetBytes("A002AD9AD73C402190C3E733D82CEA00");
    byte[] FIV = encoding.GetBytes("zyxwvutsrqponmlk");

    // Check arguments.
    if (plainBytes == null || plainBytes.Length <= 0)
        throw new ArgumentNullException("plainText");
    if (FKey == null || FKey.Length <= 0)
        throw new ArgumentNullException("Key");
    if (FIV == null || FIV.Length <= 0)
        throw new ArgumentNullException("Key");
    byte[] encrypted;
    // Create an RijndaelManaged object
    // with the specified key and IV.
    using (RijndaelManaged rijAlg = new RijndaelManaged())
    {
        rijAlg.Key = FKey;
        rijAlg.IV = FIV;
        rijAlg.Padding = PaddingMode.Zeros;
        rijAlg.Mode = CipherMode.CBC;

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

        // Create the streams used for encryption.
        using (MemoryStream msEncrypt = new MemoryStream())
        {
            using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
            {
                // plainBytes.Length = 2216 
                csEncrypt.Write(plainBytes, 0, plainBytes.Length);

                // encrypted.Length = 2208
                encrypted = msEncrypt.ToArray();
            }
        }
    }

    // Return the encrypted bytes from the memory stream.
    return encrypted;
}

Answer 1

Just calling FlushFinalBlock() resolves the multiple of 16 problem.

Answer 2

try this

    using (MemoryStream msEncrypt = new MemoryStream())
    {
        using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
        {
            csEncrypt.Write(plainBytes, 0, plainBytes.Length);
        }
        encrypted = msEncrypt.ToArray();
    }

Answer 3

It is also important to be careful while decrypting data with CryptoStream. It is advisable to read it using a loop. Calling Read only once can lead to truncated results.

using (var crypto = new CryptoStream(stream, decryptor, CryptoStreamMode.Read))
{
    plainTextBytes = new byte[cleanCipherBytes.Length];

    int read = 0, rem = plainTextBytes.Length;

    do
    {
        read = crypto.Read(plainTextBytes, read, rem);
        rem -= read;
    }
    while (read > 0);
}

This took me quite a while to figure out. I hope it saves someone else's time.