# Add a password to a PDF Encrypt a PDF so it requires a password to open, in a Zap. Connect the PDF Blocks app once: no code, and no document is stored after the Zap runs. Use this action to add a password to a PDF document, encrypting it so it can only be opened by someone who knows the password. ## Input <ParamField name="PDF Document" type="file" required> The content of the input PDF document. </ParamField> <ParamField name="Password" type="string" required> The password required to open the file. Must be between 4 and 32 characters. Characters must fall within the ASCII printable range (positions 32–126), which includes letters, numbers, spaces, and common symbols such as periods, colons, and mathematical operators. </ParamField> <ParamField name="Encryption Algorithm" type="string" required> The encryption method to use. One of `AES-128` or `AES-256`. We recommend using AES-128 as it strikes a balance between security and compatibility. </ParamField> ## Output <ParamField name="File" type="file"> A file with the password-protected PDF document. You can use it as input to other steps in your zap. </ParamField>