The Chicken and Egg Problem for checksums was solved for the IP header
checksum, and the TCP payload checksum back during the 1970s.

When calculating the checksum, set the checksum field itself to zero.
When verifying the checksum, skip over the value that is actually
present.  Perform the calculation as if it was actually set to zero.

CD and DVD images could do the same thing.

It would be enough to append a single 32-bit CRC just to ensure that
your download wasn't corrupted, or that you had a good burn, but if
you wanted to make sure that the Russian Mafia hadn't patched your
kernel, you could add one entire 2048-byte sector to your image, and
fill it all up with one big cryptographic hash.

Don Quixote
-- 
Don Quixote de la Mancha
quix...@dulcineatech.com
http://www.dulcineatech.com

   Dulcinea Technologies Corporation: Software of Elegance and Beauty.
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