Available in pre-release 3.7

In application #

To decrypt a PDF in SumatraPDF:
Or:
  • open encrypted PDF document
  • right-click for context menu
  • Document > Decrypt PDF

From command-line #

To decrypt a PDF using SumatraPDF from command-line:
SumatraPDF clean -D -p pwd foo-encrypted.pdf foo-decrypted.pdf
Flags:
  • -D : decrypt
  • -p <pwd> : provide password
You can see all flags.
You can also encrypt