How PACKERS work?

[romeo_8693]

u must have heard about this cute little soft's known as packers or exe compressors.how do they work?(theory)and how the integrity of the file maintained?(any pointers will do)

[ramprasad]

rather than PACKERS, refer them as INSTALLERS.

It is nothing but windows copy tool, which also checks for integrity and MD5 checksum.

uses regsrv to register dlls...

[romeo_8693]

dude i know installers.packers are progs that compress the exe itself,so dat it can be reverse engineered(to some extent)!!!