change geli code to write a file in boot time when correct passphrase entered

[s m]

hello all
for some reason, i want to change geli implementation. i wanna write some
thing in a file when entered passphrase in boot time is correct. (i should
change geli module(geom_eli.ko) which is loaded in boot time).
i trace code and i think i can't do it because needed library can not be
loaded in boot time. is it true or not? i mean is there any way to do
that???

thanks in advance
SAM