Deflate compression algorithm

modulename: deflate.ko

configname: CONFIG_CRYPTO_DEFLATE

Linux Kernel Configuration
└─>Cryptographic options
└─>Deflate compression algorithm
In linux kernel since version 2.6.12  
This is the Deflate algorithm (RFC1951), specified for use in
IPSec with the IPCOMP protocol (RFC3173, RFC2394).

You will most probably want this if using IPSec.

source code: