only compression
Thu, 27 Jan 2000 17:47:50 +0900

jhartmann> is there a way to abuse gnupg to only compress a file? No
jhartmann> signature, no encryption!

i don't know for sure, but gpg --store may work.  you might want to
look at the man page for gpg, that's where i found --store.

i took the text of rfc2440.txt which was 141371 bytes in size and did:

  cat rfc2440.txt | gpg --store > testfile

the size of testfile was 43799 bytes.

i was able to retrieve the contents by doing:

  cat testfile | gpg > result

the size of result was 141371 bytes and diff-ing it w/ the original file
gave no differences.

you can tweak the compression parameters as well -- i recommend
looking through the man page for that.