how to fight a password cracker

microsoft.public.dotnet.framework

14 Feb 2007 10:24 AM

Madni

Dear All,

Using pdflib library in C# I have created a pdf file which is
protected using owner password .Different options are disallowed like
print, copy contents etc. Things were working very fine untill i came
to know about some password crackers which could easily crack the
file , eliminating the password , thus making it possible for
operations like printing, copy etc .
The study showed that using user password as well will make the file
strong enough to be decrypted ,but "user password" is not a solution
in my case .

The code which actually creates a pdf file using pdflib is as under :

PDFLib obj = new PDFLib();
obj.begin_document(FileName, "masterpassword=23wdlm3ldjwld4w
permission={noprint}");

Now i wonder even that the file is encrypted using 128-bit
encryption , how a password cracker can retrieve that stored password
form the encrypted file .What operation is performed by the cracker to
remove the password and making the file accessible for all options .

Can any one please help me in this ....

Regards,
Madni