Struct RelinKeyGenerator 

pub struct RelinKeyGenerator<'a, 'b> { /* private fields */ }

A builder for creating relinearization key generation shares per party.

Each party uses the RelinKeyGenerator to generate their shares and participate in the “Protocol 2: RelinKeyGen” protocol detailed in Multiparty BFV (p6). The shares need to be aggregated between rounds:

use std::sync::Arc;
use fhe::bfv::{BfvParametersBuilder, RelinearizationKey, SecretKey};
use fhe::mbfv::{Aggregate, CommonRandomPoly, RelinKeyGenerator, RelinKeyShare, round::*};

let parameters = BfvParametersBuilder::new()
        .set_degree(4096)
        .set_moduli(&[0xffffee001, 0xffffc4001, 0x1ffffe0001])
        .set_plaintext_modulus(1 << 10)
        .build_arc()?;

// Party perspective
let mut rng = rand::rng();
let sk_share = SecretKey::random(&parameters, &mut rng);
let crp = CommonRandomPoly::new_vec(&parameters, &mut rng)?;
let rlk_generator = RelinKeyGenerator::new(&sk_share, &crp, &mut rng)?;
let rlk_r1_share = rlk_generator.round_1(&mut rng)?;

// Aggregator perspective
let r1_shares = vec![rlk_r1_share]; // all party shares go here
let rlk_r1_aggregated = RelinKeyShare::<R1Aggregated>::from_shares(r1_shares)?;

// Party perspective
let rlk_r2_share = rlk_generator.round_2(&Arc::new(rlk_r1_aggregated), &mut rng)?;

// Aggregator perspective
let r2_shares = vec![rlk_r2_share]; // all party shares go here
let rlk = RelinearizationKey::from_shares(r2_shares)?;

Implementations

impl<'a, 'b> RelinKeyGenerator<'a, 'b>

pub fn new<R: RngCore + CryptoRng>( sk_share: &'a SecretKey, crp: &'b [CommonRandomPoly], rng: &mut R, ) -> Result<Self>

Create a new relin key generator for a given party.

1. Private input: BFV secret key share
2. Public input: common random polynomial vector

pub fn round_1<R: RngCore + CryptoRng>( &self, rng: &mut R, ) -> Result<RelinKeyShare<R1>>

Generate share for round 1

pub fn round_2<R: RngCore + CryptoRng>( &self, r1: &Arc<RelinKeyShare<R1Aggregated>>, rng: &mut R, ) -> Result<RelinKeyShare<R2>>

Generate share for round 2