- Install QPDF (http://qpdf.sourceforge.net/)
choco install qpdf
- Encrypt single PDF file (http://qpdf.sourceforge.net/files/qpdf-manual.html#ref.encryption-options)
Default restrictions
qpdf --encrypt USER_PASSWORD_HERE OWNER_PASSWORD_HERE -- input.pdf input_encrypted.pdf
Custom restrictions
qpdf --encrypt USER_PASSWORD_HERE OWNER_PASSWORD_HERE -modify=none -modify-other=n -extract=n -annotate=n -print=low -- input.pdf input_encrypted.pdf