we need to encrypt the emails that contain PDFs that are coming from our laboratory management system to our clients. we do not have access to our clients machines. we dont want to issue everyone passwords because 1. they might forget it, 2. we dont want them to have to enter the password every time they view the PDF. is there a free or NOT free way to encyrpt these emails so that the client does not have to do anything to be able to open them?
is there a pdf tool that will allow for the receiving party to just enter the password ONCE and not have to do it at all after that>?
Using password-based PDF encryption is probably not secure, as the passwords would have to be very complex to avoid brute-forcing.
Instead, issue each user an SSL certificate and use S/MIME to encrypt each email. The certificate can be installed into Thunderbird or the Windows store on the client machine. If it’s stored w/o a password, decrypting the email will be automatic. Certificates can also be revoked this way.