how to verify Debian programs via checksums ?

[mark david mcCreary <mdm@one-man-isp.com>]

I've seem to have had some binary files become corrupt, and I get 

	cannot execute binary file

I figured out which package they were in via

	dpkg -S pgm-name

Removed the package and re-installed it, since the update command 
thought everything was hunky dory.

I probably have other corrupt programs on my disk and want to find them.

I'm using Debian Woody.  How would I loop thru all installed Debian 
packages, and compare the program of each package to the official 
Debian repository.

Something like an MD5 checksum ?

Or what other resources do I have at my disposal ?

Thank  you.

mark