If you have forgotten the password for a Protected PDF File, you might be interested in knowing about some free Password Recovery Tools that can be used to Recover Lost PDF File Password.
Recover Lost PDF File Password
Once a PDF File is protected by Password, it can only be opened or accesed by entering the Password that was used to protect that particular file.
This means that if you do not know the password for a protected PDF File, you will have to either remove the password from protected PDF File or Recover the Lost Password.
With this understanding, let us take a look at Common Password Recovery Methods and some better known PDF Password Recovery Programs.
1. Common Password Recovery Methods
A PDF file typically has two types of passwords – The User and Owner Passwords
- User Password – Used to prevent people from opening or viewing a PDF file
- Owner Password – Used to prevent people from printing, copying, editing, adding or deleting pages from a PDF file.
Most Password Recovery Programs make use of Brute-Force, Dictionary and Mask Attack methods to recover Lost PDF File Passwords.
Dictionary Attack – The Dictionary method tries to guess the lost password by trying out different combination of words, phrases and characters that are available in a specially maintained dictionary.
Mask Attack – This Password Recovery Method tries crack the password in short time by using common knowledge about human nature and how most people design passwords.
Brute-Force Attack – If above methods fail, Brute Force method is employed, which basically comprises of a software program designed to try out all possible word and character combinations, until the password is craked.
Although, the term “Brute Force” may sound powerful and cool, it is actually the most inefficient way to Recover Lost File Passwords.
For example, the Brute Force Method may end up using millions of trial and errors, in order to crack a simple nine digit password (johny1988) that only makes use of Name and Date of birth.
This can happen, because there are practically 13,537,086,546,263,600 ways to come up with a simple 9-digit password containing any 5 digit first Name and Year of birth.
While this may be hard to believe, it is actually supported by the following mathematical calculation:
1. 26 Upper Letter Alphabets + 26 Lower Letter Alphabets + 10 numerals= 62.
2. This means there are 62^9 possible ways to create a 9-Digit Password using any of the 26 upper case letters, 26 lower case letters and 10 numerals (1 to 9 and 0).
2. Password Recovery Tools
Now, that we have a basic understanding of various password recovery methods, let us move ahead and take a look at some of the password recovery programs that are available in the market.
1. PDF Crack
PDFCrack can recover both User and Owner passwords for PDF Files protected with 128-bit RC4 encryption.
PDF Crack is really easy to use – just upload the file from your computer and hit the crack button. You can find this tool at pdfcrack.com
2. Stellar PDF Password Recovery
Stellar PDF Password Recovery is a powerful program that can employ both Dictionary Method and Brute Force Attack to recover lost PDF File Passwords.
Dictionary Attack uses an algorithm to search for the password in a specially maintained dictionary that contains all the previously searched passwords and possible values for the password being searched.
As mentioned above, the Brute-Force method tries to crack the password by trying out all possible letter, number and character combinations that can be used to create a Password.
You can find the trial and paid versions of this password recovery tool at stellarinfo.com
3. Jihosoft PDF Password Recovery
This is another better known Password Recovery Tool capable of recovering both user and owner passwords. This program makes use of Brute Force, Dictionary and Mask Attack methods to recover Lost PDF File Password.
You can access the trial and paid versions of this Password Recovery Tool at jihosoft.com
Above information is intended to help regular users who may have lost, misplaced or forgotten the password for their own Protected PDF files.
You should never try to guess or recover the password for files that you do not own and that have been protected for a reason.