I am trying to write some code to detect whether a file has been modified. Some worms re-write the code so that a crc check comes out OK. Can I put in some code in a particular spot and if it's position is shifted, it can be detected.

Does anyone familar with nasm and tasm know the tasm equivalent of section. data Thanks.
Posted on 2002-07-07 08:44:08 by skywalker
Instead of a simple CRC, do a MD5 or SHA... should be very hard to
come up with a matching hash then ;). While this will foil automated
"attacks", it takes a lot more to stop a nasty cr4cker, but oh well.
In masm (when dealing with simplified segment model), you switch
between sections with ".data", ".data?", ".code" - who cares about tasm.
Posted on 2002-07-07 08:55:54 by f0dder

Instead of a simple CRC, do a MD5 or SHA...


Thats interesting! Where can I find more information on MD5 and SHA f0dder?
Posted on 2002-07-07 09:05:54 by JamesE
Should be rather easy to find, both are wellknown cryptographic
hashes. Rudeboy made a MD4/5 implementation in asm quite a
while ago, and there's SHA sources available too. Google :).
Posted on 2002-07-07 09:11:47 by f0dder