README

DEFENCE

DOS-era copy-protection toolkit (Turbo Pascal + x86 assembly) that binds a target EXE/COM to a machine via a ROM-derived key. It ships a Turbo Vision front-end plus small DOS utilities that perform unpacking, encryption, and stub injection. This repo is primarily historical/archival and targets 16-bit DOS environments.

Components

• DEFENCE.PAS - Turbo Vision UI that orchestrates the protection pipeline.
• ENCRYPT.ASM -> encrypt.com - encrypts the target using a ROM-derived key.
• TAIL.ASM / tail.org -> tail.com - runtime stub appended to the target.
• COM2END.ASM -> com2end.com - appends a COM stub to an EXE/COM.
• DCRYPT.ASM -> dcrypt.com - post-processing step used in the pipeline.
• TRACE.ASM -> trace.com - optional patcher for CALL offset16 sequences.
• CHECK.ASM -> check.com - sanity check for EXE header/size.
• Turbo Vision units: dialogs.pas, views.pas, stddlg.pas, etc.

Build

You need a DOS environment (or DOSBox) with Turbo Pascal 7.0 and Turbo Assembler/TLINK.

Example (DOS):

tasm encrypt.asm
tlink /t encrypt.obj

M.BAT is a local helper script for TASM/TLINK; adjust paths to your setup.

Usage

The GUI (DEFENCE.EXE) drives the same pipeline as MAKE.BAT. The batch script can be used directly:

MAKE.BAT <target.exe>

Pipeline (simplified):

1. Backup the target and copy it to asd.exe.
2. Unpack with unp (external; not included).
3. Prepare the tail stub (tail.org -> tail.com).
4. Optionally patch calls with trace.com.
5. Encrypt with encrypt.com.
6. Append the stub with com2end.
7. Finalize with dcrypt.com and replace the original file.

Notes

• 16-bit DOS only. The tooling accesses ROM/BIOS data directly and will not run on modern OSes without emulation.
• unp is referenced but not included in this repo.
• MIT License. See LICENSE.