Comparing to other blockchains (like Bitcoin/Ethereum), the specifics of Universa network and Universa Blockchain technology is that the Universa Blockchain normally does not store the data of the contracts in its distributed ledger. The Universa Blockchain works as a storage for contract validity only, but not for the content of the smart contract.
Thus, to work with the Universa contracts using some Universa client, it is not sufficient just to know the private key of the user, and get all the data of the user from the blockchain; the client should actually store the smart contracts (and private keys, if there are multiple of them) which are being worked with. Thus, each Universa client should have some Client Data Storage, which keeps track of all the involved and processed smart contracts.
There are multiple approaches of Client Data Storage, e.g.:
In Web Client
The Web Client stores the smart contracts using the end-user-encrypted Crypto Cloud. It also allows to export the contracts into downloadable
.unicon files, and to import these
.unicon files into the Crypto Cloud.
Storing the contracts in Crypto Cloud is extremely convenient and mostly transparent to the user. Using the Crypto-Cloud-enabled features like Chat, one may easily re-register the smart contract to another user and immediately send it to the new owner using. But please note that some other Univeras users are not necessarily using either the Web Client or Crypto Cloud, so for them to access the smart contracts, you may need to transfer them using different means, even fallback to sending them the
.unicon files of the contracts.
The Uniclient CLI tool may work with
.unicon files directly, as well as have some basic means of storing the contracts on the filesystem. Please note Uniclient doesn’t support the Crypto Cloud storage.
In hardware Universa clients
For other blockchains, the “hardware wallet” (like Ledger Nano S, Trezor, etc) is typically just a secure device (in the flash drive formfactor) storing the private key and performing operations using it, but not allowing the private key itself to be copied out and stolen. Basically, each such a “hardware wallet” is just a “secure key storage”, while some apps running on the computer (where this device is connected) are working as the clients.
In Universa, it is really possible to implement a fully hardware client running all the operations on itself, and using Internet just to register the contracts, or check their state. Such a hardware client will even contain the embedded Client Data Storage, not requiring any external storages (even the Crypto Cloud) to keep the smart contracts being worked with.
In client APIs/libraries
The software developers using the client APIs are usually assumed to implement their own Client Data Storage for their own means. For some more specific details, the Software development: best practices could be consulted.