You can do this with the OpenSSL command line tool:
openssl zlib -d < $IN > $OUT
Unfortunately, at least on Ubuntu, the zlib
subcommand is disabled in the default build configuration (--no-zlib
--no-zlib-dynamic
), so you would need to compile openssl
from source to use it. But it is enabled by default on Arch, for example.
Edit: Seems like the zlib
command is no longer supported on Arch either. This answer might not be useful anymore :(