[Lazarus] delphi - virus

Graeme Geldenhuys graemeg at opensoft.homeip.net
Tue Aug 25 09:36:48 CEST 2009


Florian Klaempfl wrote:
>> Probably the author found a way to keep the checksum ?
> 
> 1) On loading, the checksum is not recalculated but the compiler thrusts
> the header so the checksum can be easily patched.
> 2) FPC uses a CRC, a CRC can be easily faked today.

Without knowing to much about the compiler internals... Wouldn't a SHA1
be a better option than CRC?  For example, Git uses SHA1's to
cryptographically ensure that no revision in the repository has been
tampered with. Just a single byte change generates a completely
different SHA1.

I have a SHA1 implementation in Object Pascal (with some unit tests) if
you are interested - I used it when I was following the Git
implementation from the first revision, implementing Git using Free
Pascal as I go through the revisions. All this just for fun - how sad am
I. ;-)


Regards,
  - Graeme -

-- 
fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal
http://opensoft.homeip.net/fpgui/





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