Lock and secure sensitive PDF documents with our free PDF Password Protector. Apply strong open passwords with enterprise AES-256 or RC4-128 encryption directly inside your browser with complete privacy and zero server uploads.
Upload your sensitive PDF document into the client-side encryption workspace.
Set user open passwords and owner permissions (printing, copying, editing restrictions).
Click Encrypt PDF to apply AES 128-bit/256-bit encryption and download your protected PDF.
Applies strong AES 256-bit or RC4 128-bit encryption to restrict unauthorized document opening.
Requires password confirmation input matching to eliminate accidental lockout errors.
100% local WebCrypto browser processing guarantees passwords and PDF bytes never leave your device.
PDF security specification dictates that password protection creates an /Encrypt dictionary within the PDF trailer. For enterprise AES-256 encryption (/V 5 /R 6 standard handler), a 256-bit file encryption key (FEK) is computed using PBKDF2 hash iterations and AES-CBC cipher blocks.
When an open password is defined, the encryption engine wraps internal object streams—such as page text arrays, embedded TTF/OTF fonts, and image XObjects—with AES or RC4 encryption primitives while preserving the structural catalog hierarchy.
Executing client-side encryption via WebCrypto and @pdfsmaller/pdf-encrypt processes all byte stream mutations directly in browser RAM, ensuring passwords and document contents remain 100% confidential without external transmission.