DOS ain't dead - PK Zippers self destruct - NOT BUG it checks PSP for PK sig

PK Zippers self destruct - NOT BUG it checks PSP for PK sig (Announce)

posted by Arjay, 20.09.2016, 19:28

> Phil Katz
> implemented an anti-hack check to see if the PSP (Program Segment Prefix)
> contains his initials PK at an offset which his PKLite unpacker adds,

Checking Ben's code and reminded myself of when I looked into this about 15 years ago. Phil's PKLite professional code adds PK into 5Ch+5Dh of the loading programs PSP. Those offsets are the first 2 bytes of of a 16 byte array used for Unopened Standard FCB 1. FCB (File Control Blocks) were a C/PM legacy which had already been superseded by file handles by the time PKLite came out.

So basically to stop the anti-hack self destruct code in PKUNZIP/PKZip for DOS you just need to make sure the PK signature is present in some way in the PSP at 5Ch+5Dh when they run. Ben's code -K+ code in http://unp.bencastricum.nl/ is the easiest way.

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Complete thread:

PK Zippers self destruct - w3a537, 31.08.2016, 06:23 (Announce)
- PK Zippers self destruct - Guti, 31.08.2016, 08:23
  - PK Zippers self destruct - w3a537, 31.08.2016, 20:26
    - PK Zippers self destruct - RayeR, 02.09.2016, 11:51
      - PK Zippers self destruct - w3a537, 03.09.2016, 03:20
        PK Zippers self destruct - w3a537, 03.09.2016, 03:23
        PK Zippers self destruct - RayeR, 03.09.2016, 03:31
        PK Zippers self destruct - Laaca, 03.09.2016, 20:41
        PK Zippers self destruct - Rugxulo, 04.09.2016, 00:56
        PK Zippers self destruct - tom, 03.09.2016, 09:29
        PK Zippers self destruct - Brian_extended, 03.09.2016, 16:41
        PK Zippers self destruct - tom, 03.09.2016, 19:21
    - PK Zippers self destruct - Doug, 09.09.2016, 06:46
      - PK Zippers self destruct - w3a537, 09.09.2016, 07:33
        PK Zippers self destruct - w3a537, 09.09.2016, 07:38
        PK Zippers self destruct - RayeR, 10.09.2016, 10:37
- PK Zippers self destruct - Ninho, 10.09.2016, 10:40
- PK Zippers self destruct - NOT BUG it checks PSP for PK sig - Arjay, 20.09.2016, 19:15
  - PK Zippers self destruct - NOT BUG it checks PSP for PK sig - Arjay, 20.09.2016, 19:28