public virtual byte[] Update(byte[] b, int off, int len)
{
if (initiated)
{
return(cipher.Update(b, off, len));
}
else
{
int left = Math.Min(iv.Length - ivptr, len);
Array.Copy(b, off, iv, ivptr, left);
off += left;
len -= left;
ivptr += left;
if (ivptr == iv.Length)
{
cipher = new AESCipher(false, key, iv);
initiated = true;
if (len > 0)
{
return(cipher.Update(b, off, len));
}
}
return(null);
}
}
/// <summary>
/// Creates a new instance of
/// <see cref="OutputStreamAesEncryption"/>
/// </summary>
/// <param name="out">
/// the
/// <see cref="System.IO.Stream"/>
/// instance to be used as the destination for the encrypted content
/// </param>
/// <param name="key">the byte array containing the key for encryption</param>
/// <param name="off">offset of the key in the byte array</param>
/// <param name="len">the length of the key in the byte array</param>
public OutputStreamAesEncryption(Stream @out, byte[] key, int off, int len)
: base(@out)
{
byte[] iv = IVGenerator.GetIV();
byte[] nkey = new byte[len];
Array.Copy(key, off, nkey, 0, len);
cipher = new AESCipher(true, nkey, iv);
try {
Write(iv);
}
catch (System.IO.IOException e) {
throw new PdfException(PdfException.PdfEncryption, e);
}
}
