Protect PDF with Password — Free, 128-bit RC4 Encryption, No Sign-Up

When Should You Password-Protect a PDF?

PDF passwords are appropriate any time you need to control who can open a document. Common use cases include payslips and HR documents sent over email, financial reports shared with specific clients, legal agreements that should only be accessible to named parties, confidential proposals or pricing documents, and personal records such as tax returns or medical documents stored in cloud services. Encryption adds a critical layer of defence if the file ends up in the wrong inbox or gets accessed by an unauthorised party.

128-bit RC4 Encryption — What Does It Mean?

RC4 with a 128-bit key (PDF Revision 3) is a stream cipher that scrambles the PDF's content so it cannot be read without the correct password. It is the encryption standard built into the PDF specification and is supported universally — every PDF reader from Adobe Acrobat to Preview on macOS can open a file protected this way. While newer PDF revisions support AES-256, RC4-128 remains widely compatible and provides strong practical protection against casual or opportunistic access. The password itself is never stored by PdfDocShift — if you lose it, the file cannot be recovered.

Open Password vs. Permissions Password — What Does PdfDocShift Apply?

PDF encryption supports two password types. An open password (user password) prevents the file from being opened without the correct password. A permissions password (owner password) allows the file to open freely but restricts actions such as printing, copying, or editing. PdfDocShift applies a single password as both the open and owner password simultaneously — the protected file requires that password to open, and full document permissions are locked to the same credential. Separate open and permissions passwords are not supported.