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Amiga Plus 2004 #11
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Amiga Plus CD - 2004 - No. 11.iso
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AmiSoft
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Util
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crypt
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sign7800.lha
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sign7800.readme
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2004-06-23
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Short: Generator of a valid digital signature for an Atari 7800 cartridge
Author: Bruce Tomlin. Amiga port by Wojciech Pasiecznik/Voy/SSG^Dial^SWAT
Uploader: Wojciech Pasiecznik/Voy/SSG^Dial^SWAT (voydial@wp.pl)
Version: 1.0
Requires: MC68000+, ixemul.library
Type: util/crypt
This program will generate a valid digital signature for an Atari 7800
cartridge ROM image.
The code was created by hand-decompiling the original 7800 encryption
program for the Atari ST into plain C code, so it does not rely on any
external libraries and should compile for almost any operating system
with no muss and no fuss.
To run it:
==========
sign7800 -t filename to test for a valid existing signature only
sign7800 filename to generate a signature printed to stdout
sign7800 -w filename to generate a signature and update the image
'Filename' is the name of the file with the cartridge data in it. It
must be a binary file, with a size that is a multiple of 4K bytes. An
extra 128 bytes is allowed, so that you can use it with a .A78 file.
The '-t' option only tests to see if an existing signature is valid.
The '-w' option causes the file to be updated with a new signature if
it was not aready valid. A write will not happen if there is a problem
with $FFF8, $FFF9, or the reset vector, or if there is already a valid
signature in the file. Even with an already valid signature, a new
signature is still computed and printed to stdout.
WARNING: using the '-w' option should be safe if your file is really a 7800
cartridge image, but if it isn't, there is a possibility that data loss
to the last 128 bytes of the file could occur! Be sure that you have a
backup copy of or can re-create whatever file you use with the '-w' option!