It’s possible to use passwords to protect PDF files from being opened, printed, or altered. A PDF file that has been secured with the help of a robust password has supposedly enough protection to avoid duplication or distribution by unauthorized users (assuming, of course, that the authorized recipient who has been given the password does not share it with others). The creator of a PDF file can use password protection to limit user access to the file (document contents are encrypted), prevent printing, copying of text from the file, and editing the content in the document. However, the question arises: what happens if the password has been forgotten?
Numerous tools to remove a password from PDF can be used to gain access to a PDF despite a lost password. Here, it is important to mention that PDF password protection remover tools were initially invented to be used only under appropriate circumstances – that is, only if the original creator has lost the password or the user has a legal right to view and modify the PDF but does not have it. However, as with all applications, they were quickly misused to help unauthorized users unlock a PDF or remove permissions so that they can copy and share the document.
One might ask: how did PDF password remover tools become so effective? This article provides a clue – “Adobe’s PDF protection scheme is a classic example of security through obscurity. They encrypt the content of a PDF file and hope that no one figures out how to decrypt it.”
PDF cracking programs are highly effective in decrypting PDF files and many of them are available for free. They use various methods to remove a password from a PDF, such as dictionary attacks. Dictionary attacks use a massive database of popular and common passwords and try all of them to see if any work. The process takes maybe a few minutes for thousands of passwords. Typical passwords NOT to use include: 123456, 123456789, password,. admin, 12345678, qwerty, 1234567, 111111, photoshop, 123123, 1234567890, 000000, abc123, 1234, adobe1, macromedia, azerty, iloveyou, aaaaaa, 654321, fred. If you want to share PDF files securely, then using obvious passwords is not going to provide much protection.
ElcomSoft’s Advanced PDF Password Recovery software makes it easy to remove both password encryption and usage restrictions from Adobe Acrobat PDF files. It provides super-fast guaranteed recovery of PDF files with 40-bit encryption.
ElcomSoft’s CEO said that document-level password protection technically isn’t DRM (digital rights management). Because of the plug-in architecture of Acrobat and PDF readers, it makes PDF a less-secure platform for DRM.
A single click of a button in pdf-Recover will remove the password from a PDF, regardless of whether it has been encrypted using 40-bit RC4, 128-bit RC4 or even the latest 128-bit AES Adobe 8 Generation technology.
ElcomSoft claim that despite the 256-bit encryption, Acrobat 9 passwords are susceptible to more efficient brute forcing than Acrobat 8 due to poor implementation – a password checking routine consisting of just one call to the SHA256 hash function.
Types of PDF Passwords
In the Adobe PDF standard there are two passwords you can apply to encrypt a PDF file:
The stronger the document open password, the longer it will take to crack or remove a password from the PDF with PDF user password remover tools. The permissions password, however, can be broken trivially no matter how strong it is. This is due to inherent weaknesses (or flaws) in the design of the Acrobat Standard Security handler. See How Secure Is PDF?.
In fact, when it comes to removing PDF permissions, you don’t even need to use a password removal program – there are other, simpler methods – see Removing PDF Restrictions. These make it trivial to remove permissions from a PDF and do what you like with the document.
You therefore must add a Document Open password to the PDF or the permissions password can be easily removed. However, the dilemma is that the people you are sending protected PDF files to need to have the Document Open passwords in order to read them. So, protection is only provided if someone (i.e. an unauthorized user) gets hold of a password-protected PDF, not knowing what the password is. But even here PDF password remover companies provide PDF cracking tools that will remove anything but the strongest of Document Open passwords.
Types of PDF Password remover tools & technology
If you are looking at password remover tools for your legitimate use (to unlock PDF files that you have forgotten the password for) then you will need to exercise a great deal of caution with freely available password remover tools. Many password removal tools that are free require the user to download irrelevant software onto their computer. Some password removal tools, for example a well-known software called “PDF Unlocker”, gets the user to install unnecessary plug-ins and browser toolbars in order to use it. It is important to be careful while downloading such tools, as these additional extensions and plug-ins are often nothing but completely unnecessary bloatware that will slow a computer. A free online PDF password remover tool, or a well-known paid password remover tool such as Elcomsoft EDPR, might therefore be a wiser choice.
Current cracking tools use several techniques to remove a PDF User password and unlock PDF files:
How to remove password from PDF files
To remove PDF password protection from a PDF file, look into some of these safe PDF password remover tools:
All of the PDF password remover tools can easily remove the Permissions password (and thus the document restrictions) in seconds.
The document open password (or owner password) may be harder to remove, depending on the strength of the password used (length and character combination) and the encryption algorithm. To remove the PDF document open password, you will have to purchase PDF user password remover software, as freeware only lets you remove the permissions password from a PDF (remove PDF restrictions). Some companies, such as Elcomsoft, specialize in PDF user password remover tools using various methods such as dictionary attacks and brute force to eventually crack the password.
Be wary of PDF cracking tools that offer an online service, because you have to upload your PDF file to their servers, where it’s decrypted. If you have confidential information stored in the PDF, you may therefore want to consider PDF password removal tools that you install on your computer. Otherwise, you’re granting a third-party the ability to read and copy your sensitive information.
Removing permissions from a PDF without password removal tools
PDF permissions (also called PDF restrictions), are ‘protected’ with the use of an Permissions password. However the Permissions password can be easily removed in seconds without using PDF password remover tools:
The reason PDF permisssions password removal is so simple is that Adobe relies on the honor system for PDF password security (i.e. please obey the restrictions placed on this document). So it would be fair to say that applying PDF Permissions passwords are a waste of time because all of the above methods effectively renders them useless.
Remove protection from PDF files – is it that easy?
A well-known technology website offered technical experts the opportunity to crack a 10,000+ entry-encrypted password document and asked them to breach the security of the file. The winner of the project was able to get over 95 percent of the entries while the other participants were able to crack 75 percent, in a matter of few hours. How the ‘crackers’ did it was through the unfortunate and irresponsible use of non-randomized passwords by the account holders. Some of the commonly used passwords in the encrypted file included “123456,” “1234567,” “password,” hello123,” “hello1,” “admin” etc.
Unlocking password protected PDF files is more likely if the password protecting them is simple and weak – PDF documents are only as safe as the passwords that are safeguarding them. To prevent the data breach of a PDF file, make use of passwords that are more than seven characters long and that also include at least one number and one special character. Experts widely agree that simple words such as a straight dictionary word should not be used. Also, refrain from using short length passwords. See PDF Password Tips.
The concerns regarding locking PDF documents with passwords are extremely valid given the value and importance of the contents contained within them. Having said that, it is also important for users to be extremely cautious when sharing PDF files and documents amongst one another, as this may cause documents to be inadvertently leaked to unauthorized parties. There have been cases where even after much caution, documents have fallen into unintended hands. This is why it is extremely important to integrate additional safety measures into documents.
Protection against PDF password remover tools
To prevent users from removing the password from a PDF, employ a secure solution that does not use passwords for protection or expose keys to users or any third-party interfaces or applications.
Locklizard PDF protection software, for example, protects PDF documents without the use of passwords so there are none to forget or pass on to others.
We use AES encryption, real-time licensing, and public key technology, with keys that are never exposed to any interface for attack so that unauthorized users cannot unlock PDF files or remove permissions. We do not rely on Adobe for security (the Adobe Security Handler is seriously flawed) or insecure plugins to any third-party applications. See our DRM Technology for the methods we use to protect PDFs from unauthorized use or misuse. PDF files are locked to individual devices so they cannot be shared and additionally can be locked to IP ranges and country locations.
Protect and control your PDF documents securely no matter where they reside.
The decryption keys of a PDF file are linked to its user password. To remove password encryption from a PDF, then, you have to use a PDF user password remover. Usually, this means paying for a solution, such as Elcomsoft Password Recovery, as free tools typically only remove the permissions password.
If you’re talking about the permissions password, absolutely. You can successfully remove permissions from a PDF 100% of the time since password restrictions are completely useless. The open password you will have to crack using traditional password cracking methods, which are very effective if it is short to medium length, but too slow to be worthwhile on long passwords with many numbers and symbols.
In short: it depends how secure the password is. Modern technology can crack simple passwords of up 10 characters instantly. Add more characters and particularly symbols, numbers, and capital letters, and you could be looking at anywhere from an hour to 7 quadrillion years. Check out our infographic for more detail.
There are no apps in the Google Play store that will remove the password from a PDF file when you do not know it. If you just need to remove the permissions from a PDF, you can upload it from your phone to an online tool. However, this will provide the website owner with a decrypted version of your document, which is not recommended for confidential material.
An open password cannot be removed online or with a mobile app, so you will have to use a computer and software like Elcomsoft.
No, Locklizard does not use passwords as a security method to protect PDF files. There are no passwords to enter or remove. Only authorized users can open protected PDF files and permissions cannot be removed using third-party tools.
Locklizard provides an easy way to create a protected PDF document on your desktop which you can distribute over the Internet without fear of it being copied and shared with unauthorized users. The encrypted PDF file is locked to a user’s device, and editing, copy & paste, and printing is prevented by default. Locked PDF files cannot be modified in a PDF editor (so watermarks cannot be removed), or saved to a new PDF file that is unprotected. And if you want to allow printing then we prevent saving to a PDF printer such as MicroSoft print to PDF.
Locklizard uses secure and transparent key management with a licensing system and DRM controls to ensure your PDF documents are fully protected regardless of their location.