#fully #homomorphic #encryption #fhe


Concrete is a fully homomorphic encryption (FHE) library that implements Zama's variant of TFHE

1 release (0 unstable)

1.0.0-beta Jul 6, 2022

#2432 in Cryptography

BSD-3-Clause-Clear and GPL-2.0-or-later

86K SLoC

Concrete Core

This crate contains low-level implementations of homomorphic operators used in the concrete library.

⚠ Warning ⚠

This crate assumes that the user is comfortable with the theory behind FHE. If you prefer to use a simpler API, that will perform sanity checks on your behalf, the higher-level concrete crate should have your back.


Here is a small example of how one could use concrete-core to perform a simple operation homomorphically:

// This examples shows how to multiply a secret value by a public one homomorphically. First
// we import the proper symbols:
use concrete_core::crypto::encoding::{RealEncoder, Cleartext, Encoder, Plaintext};
use concrete_core::crypto::secret::LweSecretKey;
use concrete_core::crypto::LweDimension;
use concrete_core::crypto::lwe::LweCiphertext;
use concrete_core::math::dispersion::LogStandardDev;

// We initialize an encoder that will allow us to turn cleartext values into plaintexts.
let encoder = RealEncoder{offset: 0., delta: 100.};
// Our secret value will be 10.,
let cleartext = Cleartext(10.);
let public_multiplier = Cleartext(5);
// We encode our cleartext
let plaintext = encoder.encode(cleartext);

// We generate a new secret key which is used to encrypt the message
let secret_key_size = LweDimension(710);
let secret_key = LweSecretKey::generate(secret_key_size);

// We allocate a ciphertext and encrypt the plaintext with a secure parameter
let mut ciphertext = LweCiphertext::allocate(0u32, secret_key_size.to_lwe_size());
    &mut ciphertext,

// We perform the homomorphic operation:

// We decrypt the message
let mut output_plaintext = Plaintext(0u32);
secret_key.decrypt_lwe(&mut output_plaintext, &ciphertext);
let output_cleartext = encoder.decode(output_plaintext);

// We check that the result is as expected !
assert_eq!((output_cleartext.0 - 50.).abs() < 0.01);


This software is distributed under the BSD-3-Clause-Clear license. If you have any questions, please contact us at hello@zama.ai.


~312K SLoC