Encrypt your own or other people's PDF documents with up to 256 bit key strength (AES). Add a password to open it so that users can only view the encrypted document by entering the correct password.

To guarantee the recipients of your PDF documents that the corresponding document is original and has not been manipulated afterwards, a feature for digital signing is available in Secure-PDF. With a PKCS#12 certificate you can assign your digital signature to the document. Or just sign a PDF file by a signature image.