Encrypt PDF
Secure your PDF documents with password protection - 100% client-side
Add AES-256 password protection to PDF documents, restricting access and controlling printing, copying, and editing permissions. Encryption runs entirely in your browser — your password never leaves your device.
AES-256 PDF Encryption: Passwords, Permissions, and Standards
PDF encryption uses a symmetric cipher — AES-128 or AES-256 in modern PDFs — to encrypt the document's content streams, making them unreadable without the correct decryption key. The key is derived from the user-supplied password using a key derivation function (PDF 2.0 uses PBKDF2 with SHA-256; older formats use MD5-based derivation, which is significantly weaker).
PDF distinguishes between two password types: the user password controls document opening access, while the owner password controls permission flags — printing, copying text, modifying content, and adding comments. Setting only an owner password protects permissions without requiring a password to open the document. Setting only a user password prevents opening without requiring additional password for operations.
AES-256 encryption (PDF 1.7 extension level 8 and PDF 2.0) is the currently recommended standard. Older 40-bit RC4 (PDF 1.1) and 128-bit RC4 (PDF 1.4) encryption are trivially broken by modern tools and should never be used for actually sensitive documents. Our tool generates AES-256 encrypted PDFs by default.
Protect confidential business documents
Encrypt financial reports, HR records, and strategic plans before distributing them outside your organization.
Restrict copying and printing
Set permission flags to allow viewing but prevent copying content or printing — useful for licensed content or proprietary reports.
Secure personal documents
Add password protection to tax returns, medical records, and personal correspondence stored or emailed digitally.
Enforce edit restrictions on finalized documents
Lock a finalized contract or report against editing so recipients can view and print but not alter content.
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Upload the PDF to encrypt
Select or drag in the PDF you want to password-protect. All content and formatting will be preserved exactly in the encrypted output.
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Set user and/or owner passwords
Enter a user password to require for opening the document, and/or an owner (permissions) password to control what operations are allowed. Use a strong, unique password — AES-256 is only as secure as the password you choose.
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Configure permission flags
Select which operations to allow: printing (low or high quality), content copying, annotations, form filling, and content modification. Unselected permissions are restricted.
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Encrypt and download
Click Encrypt PDF to apply AES-256 encryption in your browser, then download the protected file.
AES-256 encryption standard
Uses the strongest PDF encryption available — AES-256 per PDF 2.0 specification — not the outdated RC4-based older formats.
Dual password support
Set separate user and owner passwords for fine-grained control: one group can open and view, while only admins can modify permissions.
Granular permission flags
Control exactly which operations are allowed — printing resolution, text extraction, form filling, and annotations — independently of each other.
Zero-knowledge processing
Password derivation and document encryption happen entirely in your browser — the password is never transmitted to any server.
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