Those who do not always want to enter a password to read an encrypted .pdf file, can easily remove the encryption from the .pdf file by converting the file one time to a .ps file and back to a .pdf file. At the first converting step you have to supply the password. This may be connected with downloading the file from the server to the FH. The bash script fh_download.sh does exactly this from the command line.
The resulting file can then be commented by a suitable program. On Linux, there is inter alia for this purpose
xournal, other operating systems offer similar programs.