Encrypt any PDF with AES-256 — the same standard used by banks and governments. Instant encryption, no account required.
AES-256 is the encryption standard used by financial institutions, government agencies, and security professionals. When you encrypt a PDF with AES-256, the content is mathematically scrambled in a way that cannot be reversed without the correct password.
The encryption is applied to every content stream in the document — text, images, fonts. The result is a standard encrypted PDF that opens in any PDF viewer, prompting for the password.
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Maximum file size: 50MB
PDF encryption applies AES-256 to all document content streams. The encryption key is derived from your password using a key derivation function. Without the correct password, the document content cannot be decrypted. The encrypted PDF is a standard PDF file that any viewer can open — it just requires the password first.
Use cases include:
Encrypting financial documents before sharing with accountants or advisors.
Securing legal documents before sending to counterparties.
Encrypting personal identification documents stored in cloud services.
Protecting confidential business documents before distribution.
Securing sensitive reports before emailing to stakeholders.
AES-256 encrypted PDFs provide strong, standard-compliant protection for sensitive documents.
Upload, set password, download encrypted document.
Upload the PDF you want to encrypt.
Set a strong password. This will be the decryption key.
Download the AES-256 encrypted PDF.
Upload, set password, download encrypted PDF. The encryption is immediate.
Your password is processed through PBKDF2 with a random salt to derive a 256-bit encryption key.
Each content stream in the PDF is encrypted using AES-256 in CBC mode.
The encryption dictionary is added to the document catalog with algorithm parameters.
The output is a standard encrypted PDF that any viewer can open with the correct password.
AES-256 encryption in PDFs follows the PDF specification's encryption dictionary.
A 256-bit key is derived from your password using PBKDF2 (Password-Based Key Derivation Function 2) with a random salt. The salt ensures that the same password produces different keys for different documents.
Each content stream (text, images, embedded fonts) is encrypted individually using AES-256 in CBC mode. The encryption is applied at the stream level, not the file level.
The encryption dictionary in the document catalog records the algorithm version, key length, and permissions flags. This allows PDF viewers to identify the encryption parameters and prompt for the password.
For documents requiring serious security, AES-256 is the appropriate standard.
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AES-256 is the encryption standard for serious document security.
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Find answers to common questions about our PDF tools
Encrypting a PDF scrambles the document content using an encryption algorithm (AES-256) so it can only be read by someone with the decryption key — which is derived from the password. Without the password, the file is unreadable.
AES-256 (Advanced Encryption Standard with 256-bit key). This is the current industry standard used by banks, governments, and security-conscious organizations. It's considered computationally unbreakable with a strong password.
In practice, yes. When you add a password to a PDF, the document is encrypted using that password. The password is the key to the encryption. Without the password, the encryption cannot be reversed.
Yes. All standard PDF viewers support AES-256 encrypted PDFs. Recipients enter the password when prompted and the viewer decrypts the content for display.
Try opening the encrypted PDF without entering the password — the viewer will prompt for a password or display an error. This confirms the encryption is active.
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