The .pka file is a renamed ZIP archive. Inside it, the activity structure and even the are stored in plain XML files. The password only blocks the graphical unlock button — it does not strongly encrypt the contents.
ferib/PacketTracerRecovery: Password Recovery tool ... - GitHub Crack Activity Wizard Password Cisco Packet Tracer
This allows the user to enter a specific "master" password (often ) to gain full access to the Activity Wizard. Default and Known Passwords: Crack Activity Wizard Password Cisco Packet Tracer