How to Encrypt a PDF with AES-256: Complete Guide
How to password-protect a PDF with AES-256 encryption. The military standard explained simply.
What is AES-256 encryption?
AES-256 (Advanced Encryption Standard with a 256-bit key) is the most secure symmetric encryption standard in the world. It is used by governments, militaries, and banks to protect the most sensitive data.
For a PDF, AES-256 encryption means the file content is unreadable without the password. Even if someone intercepts the file, they cannot read it without the key.
AES-256 is considered unbreakable with current technology. It would take billions of years for a supercomputer to brute-force a 256-bit key.
Why encrypt locally?
Encryption only makes sense if the document is in clear text before encryption. If you use an online tool, your document transits in clear text to their servers, then is encrypted there. The benefit of encryption is negated by the transit.
SafePDF encrypts your PDFs on your machine, before any possible transfer. The password never leaves your computer. The encrypted file can then be safely shared by email, cloud, or USB drive.
SafePDF uses qpdf, a recognized open-source tool, for AES-256 encryption.
How to encrypt a PDF with SafePDF
1. Open the "Encrypt PDF" tool in SafePDF.
2. Select your PDF file.
3. Enter a strong password (minimum 12 characters, mix of letters, numbers, and symbols).
4. Confirm the password.
5. Click "Encrypt". The file is encrypted locally with AES-256.
6. Save the encrypted PDF.
Warning: there is no way to recover an encrypted PDF if you forget the password. Keep it safe.
PDF password best practices
Use a password of at least 12 characters.
Mix uppercase, lowercase, numbers, and symbols.
Do not reuse the same password as for other services.
Communicate the password via a different channel than the file (e.g., PDF by email, password by SMS).
In business, use a password manager to securely share access.
SafePDF processes all your PDFs 100% locally. No file ever leaves your machine.