It really depends on the encryption algorithms , If It's a two-way hashing algorithm (can be both encrypted and decrypted using a key) then It shouldn't be that hard but It could be very hard to do If its one-way hashing algorithm such as MD5 and will require brute-force / dictionary attacks. I personally would use the second kind of services If it's effective.
Yes, I can try both of them. I am still accepting new opinions and idea to this service. If I do not get too many of them soon, you will have a private hash decrypting service from me, OmegaStarScream lol.