Available in pre-release 3.7
To decrypt a PDF using SumatraPDF from command-line:
SumatraPDF clean -D -p pwd foo-encrypted.pdf foo-decrypted.pdfFlags:
-D: decrypt-p <pwd>: provide password
You can see all flags.
You can also encrypt
SumatraPDF clean -D -p pwd foo-encrypted.pdf foo-decrypted.pdf-D : decrypt-p <pwd> : provide password