Encryption/decryption of PB DOS chain files

[James Desiderio]

I'm developing something that makes use of encrypting and decrypting the chain files before they're ran. The chain files will be acting as data files for the main program to load and utilize, but are protected to prevent direct editing. I know that I can decrypt the chain file to the hard drive and then run the chain file, but was hoping for a more secure method.

EXE/COM encryptors work by decrypting the entire program in memory and running the executable at the specified address. Is it possible to load a chain file into memory and locate its position to decrypt, and then have it run?

Thanks.

[Michael Mattias]

I'll guess no.

Were this Windows rather than DOS, and a DLL rather than a PBC, then I'd say, "maybe," but the inner workings of the "CHAIN" procedure are the very definition of "proprietary."

But there is nothing to stop you from writing your program differently - encrypt only what you have to encrypt, not all the executable code; and that you can do with a simple...

GET #hFile, ,Record
CALL DecryptRecord (Record)

.. and bingo, you're done.

MCM