Removing password from password protected pdf file

[Peng Yu]

On Thu, Feb 4, 2010 at 10:13 AM, Patton Echols <p.echols at comcast.net> wrote:
> On 02/04/2010 07:51 AM, Peng Yu wrote:
>> There are a couple of password removing software for pdf on windows.
>> I'm wondering if there is such a software in ubuntu or, more broadly,
>> in linux. Could somebody share with me if you know it?
>>
> Do you know the password and want to disable it?  Try pdftk  It is  CLI
> program in the repositories.  You will need to read the man page after
> install.  But it is fairly straightforward.
>
> If you are looking for a method to discover or crack an unknown
> password, I don't know of any but someone else might.

I want a software that can crack the password.