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After developing your circuit, you may want to deploy it. However, sharing the details of your circuit with every client might not be desirable. Further, you might want to perform the computation in dedicated servers. In this case, you can use the Client and Server features of Concrete-Numpy.

Development of the circuit

You can develop your circuit like we've discussed in the previous chapters. Here is a simple example:
import concrete.numpy as cnp
@cnp.compiler({"x": "encrypted"})
def function(x):
return x + 42
inputset = range(10)
circuit = function.compile(inputset)
Once you have your circuit, you can save everything the server needs like so:
All you need to do now is to send server.zip to your computation server.

Setting up a server

You can load the server.zip you get from the development machine as follows:
import concrete.numpy as cnp
server = cnp.Server.load("server.zip")
At this point, you will need to wait for requests from clients. The first likely request is for ClientSpecs.
Clients need ClientSpecs to generate keys and request computation. You can serialize ClientSpecs like so:
serialized_client_specs: str = server.client_specs.serialize()
Then, you can send it to the clients requesting it.

Setting up clients

After getting the serialized ClientSpecs from a server, you can create the client object like this:
client_specs = cnp.ClientSpecs.unserialize(serialized_client_specs)
client = cnp.Client(client_specs)

Generating keys (on the client)

Once you have the Client object, you can perform key generation:
This method generates encryption/decryption keys and evaluation keys.
The server requires evaluation keys linked to the encryption keys that you just generated. You can serialize your evaluation keys as shown below:
serialized_evaluation_keys: bytes = client.evaluation_keys.serialize()
After serialization, you can send the evaluation keys to the server.
Serialized evaluation keys are very big in size, so you may want to cache them on the server instead of sending them with each request.

Encrypting inputs (on the client)

You are now ready to encrypt your inputs and request the server to perform the computation. You can do it like so:
serialized_args: bytes = client.encrypt(7).serialize()
The only thing left to do is to send serialized args to the server.

Performing computation (on the server)

Upon having the serialized evaluation keys and serialized arguments, you can unserialize them like so:
unserialized_evaluation_keys = cnp.EvaluationKeys.unserialize(serialized_evaluation_keys)
unserialized_args = server.client_specs.unserialize_public_args(serialized_args)
And you can perform the computation as well:
public_result = server.run(unserialized_args, unserialized_evaluation_keys)
serialized_public_result: bytes = public_result.serialize()
Finally, you can send the serialized public result back to the client, so they can decrypt it and get the result of the computation.

Decrypting the result (on the client)

Once you have received the public result of the computation from the server, you can unserialize it:
unserialized_public_result = client.specs.unserialize_public_result(serialized_public_result)
Finally, you can decrypt the result like so:
result = client.decrypt(unserialized_public_result)
assert result == 49