As explained in the introduction, some types (Serverkey, Ciphertext) are meant to be shared with the server that does the computations.
The easiest way to send these data to a server is to use the serialization and deserialization features. TFHE-rs uses the serde framework, so serde's Serialize and Deserialize are implemented.
To be able to serialize our data, a data format needs to be picked. Here, bincode is a good choice, mainly because it is binary format.
# Cargo.toml[dependencies]# ...bincode ="1.3.3"
// main.rsuse std::io::Cursor;use tfhe::integer::{gen_keys_radix, ServerKey, RadixCiphertext};use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS;fnmain() ->Result<(), Box<dyn std::error::Error>> {// We generate a set of client/server keys, using the default parameters:let num_block =4;let (client_key, server_key) =gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS, num_block);let msg1 =201;let msg2 =12;// message_modulus^vec_lengthlet modulus = client_key.parameters().message_modulus().0.pow(num_block asu32) asu64;let ct_1 = client_key.encrypt(msg1);let ct_2 = client_key.encrypt(msg2);letmut serialized_data =Vec::new(); bincode::serialize_into(&mut serialized_data, &server_key)?; bincode::serialize_into(&mut serialized_data, &ct_1)?; bincode::serialize_into(&mut serialized_data, &ct_2)?;// Simulate sending serialized data to a server and getting// back the serialized resultlet serialized_result =server_function(&serialized_data)?;let result:RadixCiphertext= bincode::deserialize(&serialized_result)?;let output:u64= client_key.decrypt(&result);assert_eq!(output, (msg1 + msg2) % modulus);Ok(())}fnserver_function(serialized_data:&[u8]) ->Result<Vec<u8>, Box<dyn std::error::Error>> {letmut serialized_data =Cursor::new(serialized_data);let server_key:ServerKey= bincode::deserialize_from(&mut serialized_data)?;let ct_1:RadixCiphertext= bincode::deserialize_from(&mut serialized_data)?;let ct_2:RadixCiphertext= bincode::deserialize_from(&mut serialized_data)?;let result = server_key.unchecked_add(&ct_1, &ct_2);let serialized_result = bincode::serialize(&result)?;Ok(serialized_result)}