Batboard

Can an XTS3000 be be rekeyed on a digital non-trunking system? If so, what prevents non authorized receivers from being re keyed too?

Yes.

Every radio has a unique ID.

Every authorized radio also has a unique 'shadow key' which, if lost, will keep the radio from being rekeyed until that shadow key is restored by manually reloading it from the KMC.

Elroy

you will also find that many (MANY) Motorola shops keep KVL's in the back room loaded with shadow keys...

they use these loaders when working on various agencies cars and need to request new keys before leaving the shop...