how to get rid of the MD5 in .ndb sig files

hi, everyone,

 I am doing some kindof research on string match right now and I was trying to
use ClamAV-signatures(daily.ndb and main.ndb, obtained by sigtool) as a simulation source.
but I do not know how to retrieve the original signatures which are
encrypted with MD5 in a file format: ndb, right? so if I wanna turn
those encrypted sigs back,or say decrypt them, what exactly can I do?

thank you very much~
Really really appreciate your help~

P.S.,
some examples of .ndb rule:
Trojan.Packed-6:1:EP+0:807c2408015690eb
Email.Phishing.RB-1738:4:*:687474703a2f2f7777772e706f737465696e632e636f6d2f