Userhash
From AMule Project FAQ
This user hash is stored in the preferences.dat file and is used to grant earned credits with other clients. aMule (like eMule) can use an asymmetric encryption to avoid exploiting or manipulating other user hash values. The method uses a private and a public key to ensure a correct and unique identification on other clients.
Secure User Identification can be turned on in Preferences -> Connection (since aMule 2.x). It is strongly recommended to use it.
