Concrete Operates oN Ciphertexts Rapidly by Extending TfhE

Concrete is a fully homomorphic encryption (FHE) library that implements Zama's variant of TFHE. Concrete is based on the Learning With Errors (LWE) problem and on the Ring Learning With Errors (RLWE) problem, which are well studied cryptographic hardness assumptions believed to be secure even against quantum computers.

Use concrete in your own project

You can use cargo new play_with_fhe to create a new project. You need to add the Concrete library as a dependency in your Rust project.

To do so, simply add the dependency in the Cargo.toml file. Here is a simple example:

[package]
name = "play_with_fhe"
version = "0.1.0"
authors = ["FHE Curious"]
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
concrete = "^0.1"

Now, you can run your project with the RUSTFLAGS="-C target-cpu=native" cargo run --release command.

Example

use concrete::*;

fn main() -> Result<(), CryptoAPIError> {
  // generate a secret key
  let secret_key = LWESecretKey::new(&LWE128_630);

  // the two values to add
  let m1 = 8.2;
  let m2 = 5.6;

  // specify the range and precision to encode messages into plaintexts
  // here we encode in [0, 10[ with 8 bits of precision and 1 bit of padding
  let encoder = Encoder::new(0., 10., 8, 1)?;

  // encode the messages into plaintexts
  let p1 = encoder.encode_single(m1)?;
  let p2 = encoder.encode_single(m2)?;

  // encrypt plaintexts
  let mut c1 = VectorLWE::encrypt(&secret_key, &p1)?;
  let c2 = VectorLWE::encrypt(&secret_key, &p2)?;

  // add the two ciphertexts homomorphically
  c1.add_with_padding_inplace(&c2)?;

  // decrypt and decode the result
  let m3 = c1.decrypt_decode(&secret_key)?;

  // print the result and compare to non-FHE addition
  println!("Real: {} + {} = {}", m1, m2, m1 + m2);
  println!(
    "FHE: {} + {} = {}",
    p1.decode()?[0],
    p2.decode()?[0],
    m3[0]
  );
  Ok(())
}