Module tfhe::shortint

Available on crate feature shortint only.

Welcome to the TFHE-rs shortint module documentation!

Special module attributes

cbindgen:ignore

Description

This library makes it possible to execute modular operations over encrypted short integer.

It allows to execute an integer circuit on an untrusted server because both circuit inputs and outputs are kept private.

Data are encrypted on the client side, before being sent to the server. On the server side every computation is performed on ciphertexts.

The server however, has to know the integer circuit to be evaluated. At the end of the computation, the server returns the encryption of the result to the user.

Keys

This crates exposes two type of keys:

• The ClientKey is used to encrypt and decrypt and has to be kept secret;
• The ServerKey is used to perform homomorphic operations on the server side and it is meant to be published (the client sends it to the server).

Quick Example

The following piece of code shows how to generate keys and run a small integer circuit homomorphically.

use tfhe::shortint::gen_keys;
use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS;

// We generate a set of client/server keys, using the default parameters:
let (mut client_key, mut server_key) = gen_keys(PARAM_MESSAGE_2_CARRY_2_KS_PBS);

let msg1 = 1;
let msg2 = 0;

// We use the client key to encrypt two messages:
let ct_1 = client_key.encrypt(msg1);
let ct_2 = client_key.encrypt(msg2);

// We use the server public key to execute an integer circuit:
let ct_3 = server_key.unchecked_add(&ct_1, &ct_2);

// We use the client key to decrypt the output of the circuit:
let output = client_key.decrypt(&ct_3);
assert_eq!(output, 1);

Re-exports

• pub use ciphertext::Ciphertext;
• pub use ciphertext::CompressedCiphertext;
• pub use ciphertext::PBSOrder;
• pub use client_key::ClientKey;
• pub use key_switching_key::KeySwitchingKey;
• pub use parameters::CarryModulus;
• pub use parameters::CiphertextModulus;
• pub use parameters::ClassicPBSParameters;
• pub use parameters::EncryptionKeyChoice;
• pub use parameters::MaxNoiseLevel;
• pub use parameters::MessageModulus;
• pub use parameters::MultiBitPBSParameters;
• pub use parameters::PBSParameters;
• pub use parameters::ShortintParameterSet;
• pub use parameters::WopbsParameters;
• pub use public_key::CompactPublicKey;
• pub use public_key::CompressedCompactPublicKey;
• pub use public_key::CompressedPublicKey;
• pub use public_key::PublicKey;
• pub use server_key::CheckError;
• pub use server_key::CompressedServerKey;
• pub use server_key::ServerKey;

Modules

• ciphertext
• client_key
  Module with the definition of the ClientKey.
• engine
  Module with the engine definitions.
• key_switching_key
  This module defines KeySwitchingKey
• oprf
• parameters
  Module with the definition of cryptographic parameters.
• prelude
  Module with the definition of the prelude.
• public_key
  Module with the definition of the encryption PublicKey.
• server_key
  Module with the definition of the ServerKey.
• wopbs
  Module with the definition of the WopbsKey (WithOut padding PBS Key).

Functions

• gen_keys
  Generate a couple of client and server keys.