Trouble loading PDF document

GemBox.Pdf
5

Hi Arild,

Please try to apply the following code on your file:

var desktop = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);

var fileName = "your-file-name.pdf";

var str = new string(Array.ConvertAll(File.ReadAllBytes(Path.Combine(desktop, fileName)), b => (char)b));

if (str.Contains("/XRef") || str.Contains("/ObjStm"))
{
    Console.WriteLine("PDF file probably contains cross-reference stream or object stream and cannot be processed.");
    return;
}

// Strip all streams.
str = Regex.Replace(str, @"(?<start>\bstream(\r\n|\n))(?<data>(.|\n)*?)(?<end>(\r\n|\r|\n)endstream\b)", m => m.Groups["start"].Value + new string(' ', m.Groups["data"].Length) + m.Groups["end"].Value);

// Strip all literal strings.
bool hasBalancedParentheses;
do
{
    hasBalancedParentheses = false;
    str = Regex.Replace(str, @"\((.|\n)*?\)", m =>
    {
        var lastIndex = m.Value.LastIndexOf('(');
        if (lastIndex > 0 && str[lastIndex - 1] != '\\')
        {
            hasBalancedParentheses = true;
            return '(' + new string(' ', m.Length - 1);
        }

        return '(' + new string(' ', m.Length - 2) + ')';
    });
}
while (hasBalancedParentheses);

// Strip all hexadecimal strings.
str = Regex.Replace(str, @"((?<!<)<(?!<))[^>]*?>", m => '<' + new string('0', m.Length - 2) + '>');

File.WriteAllBytes(Path.Combine(desktop, Path.GetFileNameWithoutExtension(fileName) + "-stripped" + Path.GetExtension(fileName)), Array.ConvertAll(str.ToCharArray(), c => (byte)c));

If your file doesn’t contain cross-reference streams (/XRef) nor object streams( /ObjStm), this code should be able to replace the content of all streams and literal strings with spaces and content of all hexadecimal strings with zeros without making the cross-reference table invalid.

Changing other objects is not required because PDF encryption encrypts only strings and streams.

Regards,
Stipo