Such paid programs should also be online.
Many do not is no possibility to buy a very powerful computer, there is no possibility to wait a whole month (after all, a person does not remember in which language he wrote the password in his native language or in English).

Dimma, to provide an online server or farm of servers that could be used by subscribers to brute-force passwords on anything would likely result in SLOWER try rate than using your own dedicated PC since it could be shared by thousands of people grinding the whole process to a near halt! First things first, maximize the local processing capabilities of the local machine, include multi-core AND simultaneous GPU multicore processing. If you then want to rent/lease a server and dedicate it solely to your own brute forcing of a password then you might manage a slightly better speed.

Another optimization would be segmented brute forcing where different machines are dynamically allocated different passphrase search ranges and each machine subdivides their allotted passphrase ranges for each processing core to maximize possible processing available.

Dimma, It is a good suggestion. We will prepare the online tool

Dimma, it is true.

TK, wow, you suggestions are awesome. Thank you so much. We will update this application with your ideas!

Its easy to create your own PDF with a password though. Why would you want to scan a folder to find password-ed ones?

Chris Locke (CS Computer Services), why ? because I wanted to test it in a real life situation with a real password protected file. The program is not intended to play with files you just created...

Aah, it sounded like you were struggling to test the program with a password-protected PDF and you couldn't find one.

Peter Blaise, Thank you! Your suggestions are important for us to improve user experience.

papin, not from the selections shown in the program. There is no custom character input box that would allow accented letters or other odd characters that might still be legal password characters.

papin, same here- the captcha is pain.

> the captcha is pain

Stops the bots though. :-)

George James Ducas, theoretically, this application is capable of calculating the only and correct password. The most important thing I should boost is the speed of calculation.

support@pdfpasswordrecover.com, I am running a new computer with i7 and 64 bit, you are right, needs a faster calculating approach, perhaps running several sequences simultaneously? i wish i could help, but it would help to be faster

support@pdfpasswordrecover.com, may i suggest you optimise the decryption testing routines in processor specific assembly language, wheither CPU or GPU and try and engineer it so the code loops and data segment that is test decrypted should reside within the level 1 caches for as long as possible and if that fails then level 2 cache, do not code the grunt work using any .NET framework, use .NET for the GUI if you must but not for any number crunching!

XP-Man, Sorry for that. This application requires .Net Framework 4.0 or above right now. We will release a new version which supports Win XP soon. We will inform you if you are kind to leave your email address for us.

Chris Locke (CS Computer Services), Correct. This application will try all combinations of passwords and get the correct one.

But can you resume from a point? If the program has been running for 3 weeks, then Windows 10 decides to reboot to install necessary updates, would you have to start at the beginning? That would be a pain...

Hi, Bill Rutan, Sorry for the inconvenience we bring to you. We have never encounter such issue when we are testing our application. Would you mind giving us more detailed information such as your system environment to our support team? You can send an e-mail to: support@pdfpasswordrecover.com

Best Regards!

Bill Rutan, try downloading the file from the vendors site listed as "Homepage:" and using the registration information in the Readme.txt in the giveaway zip bundle.