# Registry DB
Registry Database census require by far the most involvement with respect to user management. This method comes from the legacy Vocdoni mobile application, which was designed around self-sovereign user identities and subscription to organizations.
The user registry is a private component used by entities to manage and generate census of voters. The registry may have a standard database with the private details of the entity's members and their public keys. Users must secure their own private keys (this is best suited for a mobile application with encrypted memory) and sign-up to the entity by sending their public key hash along with their identifiable information to this private database.
When the entity wants to create a governance process, the administrator will use the registry to select the group of users matching a certain criteria, for example
age < 40. The backend, in this case, will then select users
0,1,2 and create a Merkle tree with the corresponding public key hashes, according to the Census Merkle Tree schema.
# Exporting the census
The registry backend will finally:
- Export the Merkle tree of pubkey hashes and make them available via IPFS or similar
- Publish the Root Hash on the Process Smart Contract
- Publish the IPFS URI of the Merkle tree on the Process Smart Contract
With the census details and the rest of parameters, a process is ready to be created by the entity.