DEFLATE compression tools

[Tom Scavo]

I'm trying to write a bash script that DEFLATEs and base-64 encodes an
AuthnRequest as described in SAML Core. I can use openssl to base-64
encode but I can't find a bash tool that will do DEFLATE compression.

(Yes, I know I can retrieve an AuthnRequest from a suitably configured
SP but the ability to construct an AuthnRequest locally is more
flexible.)

May I ask how the Shib SP does this?

Thanks,

Tom