Two Types of PDF Passwords
An open password (also called a user password) controls who can open and read the document. Anyone without this password will see a prompt when they try to open the file. A permissions password (also called an owner password) does not prevent opening the file but restricts what the reader can do — printing, copying text, editing, and form-filling.
AES-256 Encryption: What It Means
PDF encryption strength depends on the algorithm used. Older tools use 40-bit or 128-bit RC4 encryption, which is weak and can be broken with modern hardware. AES-256 (Advanced Encryption Standard with 256-bit keys) is the current standard — the same encryption used for securing government and financial data worldwide.
How to Choose a Strong Password
A strong PDF password should be at least 12 characters long and combine uppercase letters, lowercase letters, numbers, and special characters. Avoid names, dates, or common words. Importantly: if you lose the password, there is no recovery option. Store the password in a secure password manager before sending the protected file.
How to Password Protect a PDF Online - Step by Step
Open the ToolMint Protect PDF tool. Upload the PDF you want to protect. Enter your chosen password and confirm it. Select the encryption level — AES-256 is recommended. Optionally set permission restrictions. Click Protect PDF and download the encrypted file. Verify protection by opening the downloaded file — you should be prompted for the password immediately.
When to Remove a Password Instead
If you receive a password-protected PDF that you are authorized to edit and the protection is no longer needed, use the Unlock PDF tool to remove it. This is useful when merging several protected files into one. Only remove passwords from files you are authorized to access.