Replace indices by "id"s.
The previous implementation was using an "index" to refer to a particular FROST participant. These references are handled in a different manner now, so they were changed to "id"s (identifiers).
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parent
55cca1b3ba
commit
4ff263fa62
93
src/frost.rs
93
src/frost.rs
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@ -62,11 +62,12 @@ impl From<jubjub::ExtendedPoint> for Public {
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/// reconstruct the secret; in this case we use Shamir's secret sharing.
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#[derive(Clone)]
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pub struct Share {
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receiver_index: u64,
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/// The receiver id.
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receiver_id: u64,
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/// Secret Key.
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pub(crate) value: Secret,
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value: Secret,
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/// The commitments to be distributed among signers.
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pub(crate) commitment: ShareCommitment,
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commitment: ShareCommitment,
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}
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/// A Jubjub point that is a commitment to one coefficient of our secret
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@ -105,8 +106,8 @@ pub struct GroupCommitment(pub(crate) jubjub::AffinePoint);
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pub struct SharePackage {
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/// The public signing key that represents the entire group.
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pub(crate) group_public: VerificationKey<SpendAuth>,
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/// Denotes the participant index each share is owned by.
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pub index: u64,
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/// Denotes the participant id each share is owned by.
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pub id: u64,
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/// This participant's public key.
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pub(crate) public: Public,
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/// This participant's share.
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@ -128,7 +129,7 @@ impl TryFrom<SharePackage> for KeyPackage {
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verify_share(&sharepackage.share)?;
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Ok(KeyPackage {
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index: sharepackage.index,
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id: sharepackage.id,
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secret_share: sharepackage.share.value,
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public: sharepackage.public,
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group_public: sharepackage.group_public,
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@ -144,7 +145,7 @@ impl TryFrom<SharePackage> for KeyPackage {
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/// [`KeyPackage`]s, which they store to later use during signing.
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#[allow(dead_code)]
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pub struct KeyPackage {
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index: u64,
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id: u64,
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secret_share: Secret,
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public: Public,
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group_public: VerificationKey<SpendAuth>,
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@ -189,13 +190,13 @@ pub fn keygen_with_dealer<R: RngCore + CryptoRng>(
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for share in shares {
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let signer_public = Public(SpendAuth::basepoint() * share.value.0);
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sharepackages.push(SharePackage {
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index: share.receiver_index,
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id: share.receiver_id,
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share: share.clone(),
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public: signer_public,
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group_public,
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});
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signer_pubkeys.insert(share.receiver_index, signer_public);
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signer_pubkeys.insert(share.receiver_id, signer_public);
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}
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Ok((
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@ -216,7 +217,7 @@ pub fn keygen_with_dealer<R: RngCore + CryptoRng>(
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fn verify_share(share: &Share) -> Result<(), &'static str> {
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let f_result = SpendAuth::basepoint() * share.value.0;
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let x = Scalar::from(share.receiver_index as u64);
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let x = Scalar::from(share.receiver_id as u64);
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let (_, result) = share.commitment.0.iter().fold(
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(Scalar::one(), jubjub::ExtendedPoint::identity()),
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@ -328,7 +329,7 @@ fn generate_shares<R: RngCore + CryptoRng>(
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value += secret.0;
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shares.push(Share {
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receiver_index: id,
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receiver_id: id,
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value: Secret(value),
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commitment: commitment.clone(),
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});
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@ -390,19 +391,19 @@ impl SigningNonces {
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/// SigningCommitment can be used for exactly *one* signature.
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#[derive(Copy, Clone)]
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pub struct SigningCommitments {
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/// The participant index
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pub(crate) index: u64,
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/// The participant id.
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id: u64,
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/// The hiding point.
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pub(crate) hiding: jubjub::ExtendedPoint,
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hiding: jubjub::ExtendedPoint,
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/// The binding point.
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pub(crate) binding: jubjub::ExtendedPoint,
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binding: jubjub::ExtendedPoint,
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}
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impl From<(u64, &SigningNonces)> for SigningCommitments {
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/// For SpendAuth signatures only, not Binding signatures, in RedJubjub/Zcash.
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fn from((index, nonces): (u64, &SigningNonces)) -> Self {
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fn from((id, nonces): (u64, &SigningNonces)) -> Self {
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Self {
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index,
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id,
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hiding: SpendAuth::basepoint() * nonces.hiding,
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binding: SpendAuth::basepoint() * nonces.binding,
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}
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@ -429,8 +430,8 @@ pub struct SignatureResponse(pub(crate) Scalar);
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/// with all other signer's shares into the joint signature.
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#[derive(Clone, Copy, Default)]
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pub struct SignatureShare {
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/// Represents the participant index.
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pub(crate) index: u64,
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/// Represents the participant id.
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pub(crate) id: u64,
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/// This participant's signature over the message.
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pub(crate) signature: SignatureResponse,
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}
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@ -467,18 +468,14 @@ impl SignatureShare {
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/// perform the first round. Batching entails generating more than one
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/// nonce/commitment pair at a time. Nonces should be stored in secret storage
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/// for later use, whereas the commitments are published.
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<<<<<<< HEAD
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=======
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///
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>>>>>>> 316082b (Change the type of the identifiers from u8 to u64)
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/// The number of nonces is limited to 255. This limit can be increased if it
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/// turns out to be too conservative.
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// TODO: Make sure the above is a correct statement, fix if needed in:
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// https://github.com/ZcashFoundation/redjubjub/issues/111
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pub fn preprocess<R>(
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num_nonces: u8,
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participant_index: u64,
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participant_id: u64,
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rng: &mut R,
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) -> (Vec<SigningNonces>, Vec<SigningCommitments>)
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where
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@ -489,7 +486,7 @@ where
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for _ in 0..num_nonces {
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let nonces = SigningNonces::new(rng);
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signing_commitments.push(SigningCommitments::from((participant_index, &nonces)));
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signing_commitments.push(SigningCommitments::from((participant_id, &nonces)));
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signing_nonces.push(nonces);
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}
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@ -498,7 +495,7 @@ where
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/// Generates the binding factor that ensures each signature share is strongly
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/// bound to a signing set, specific set of commitments, and a specific message.
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fn gen_rho_i(index: u64, signing_package: &SigningPackage) -> Scalar {
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fn gen_rho_i(id: u64, signing_package: &SigningPackage) -> Scalar {
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// Hash signature message with HStar before deriving the binding factor.
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//
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// To avoid a collision with other inputs to the hash that generates the
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@ -512,11 +509,11 @@ fn gen_rho_i(index: u64, signing_package: &SigningPackage) -> Scalar {
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let mut hasher = HStar::default();
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hasher
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.update("FROST_rho".as_bytes())
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.update(index.to_be_bytes())
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.update(id.to_be_bytes())
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.update(message_hash.to_bytes());
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for item in signing_package.signing_commitments.iter() {
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hasher.update(item.index.to_be_bytes());
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hasher.update(item.id.to_be_bytes());
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let hiding_bytes = jubjub::AffinePoint::from(item.hiding).to_bytes();
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hasher.update(hiding_bytes);
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let binding_bytes = jubjub::AffinePoint::from(item.binding).to_bytes();
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@ -543,8 +540,8 @@ fn gen_group_commitment(
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}
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let rho_i = bindings
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.get(&commitment.index)
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.ok_or("No matching commitment index")?;
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.get(&commitment.id)
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.ok_or("No matching commitment id")?;
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accumulator += commitment.hiding + (commitment.binding * rho_i)
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}
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@ -568,17 +565,17 @@ fn gen_challenge(
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/// Generates the lagrange coefficient for the i'th participant.
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fn gen_lagrange_coeff(
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signer_index: u64,
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signer_id: u64,
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signing_package: &SigningPackage,
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) -> Result<Scalar, &'static str> {
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let mut num = Scalar::one();
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let mut den = Scalar::one();
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for commitment in signing_package.signing_commitments.iter() {
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if commitment.index == signer_index {
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if commitment.id == signer_id {
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continue;
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}
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num *= Scalar::from(commitment.index as u64);
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den *= Scalar::from(commitment.index as u64) - Scalar::from(signer_index as u64);
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num *= Scalar::from(commitment.id as u64);
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den *= Scalar::from(commitment.id as u64) - Scalar::from(signer_id as u64);
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}
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if den == Scalar::zero() {
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@ -608,11 +605,11 @@ pub fn sign(
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HashMap::with_capacity(signing_package.signing_commitments.len());
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for comm in signing_package.signing_commitments.iter() {
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let rho_i = gen_rho_i(comm.index, &signing_package);
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bindings.insert(comm.index, rho_i);
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let rho_i = gen_rho_i(comm.id, &signing_package);
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bindings.insert(comm.id, rho_i);
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}
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let lambda_i = gen_lagrange_coeff(share_package.index, &signing_package)?;
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let lambda_i = gen_lagrange_coeff(share_package.id, &signing_package)?;
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let group_commitment = gen_group_commitment(&signing_package, &bindings)?;
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@ -623,7 +620,7 @@ pub fn sign(
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);
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let participant_rho_i = bindings
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.get(&share_package.index)
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.get(&share_package.id)
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.ok_or("No matching binding!")?;
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// The Schnorr signature share
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@ -632,7 +629,7 @@ pub fn sign(
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+ (lambda_i * share_package.share.value.0 * challenge);
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Ok(SignatureShare {
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index: share_package.index,
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id: share_package.id,
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signature: SignatureResponse(signature),
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})
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}
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@ -661,8 +658,8 @@ pub fn aggregate(
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HashMap::with_capacity(signing_package.signing_commitments.len());
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for comm in signing_package.signing_commitments.iter() {
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let rho_i = gen_rho_i(comm.index, &signing_package);
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bindings.insert(comm.index, rho_i);
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let rho_i = gen_rho_i(comm.id, &signing_package);
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bindings.insert(comm.id, rho_i);
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}
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let group_commitment = gen_group_commitment(&signing_package, &bindings)?;
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@ -670,16 +667,16 @@ pub fn aggregate(
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let challenge = gen_challenge(&signing_package, &group_commitment, &pubkeys.group_public);
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for signing_share in signing_shares {
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let signer_pubkey = pubkeys.signer_pubkeys[&signing_share.index];
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let lambda_i = gen_lagrange_coeff(signing_share.index, &signing_package)?;
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let signer_pubkey = pubkeys.signer_pubkeys[&signing_share.id];
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let lambda_i = gen_lagrange_coeff(signing_share.id, &signing_package)?;
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let signer_commitment = signing_package
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.signing_commitments
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.iter()
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.find(|comm| comm.index == signing_share.index)
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.find(|comm| comm.id == signing_share.id)
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.ok_or("No matching signing commitment for signer")?;
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let commitment_i =
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signer_commitment.hiding + (signer_commitment.binding * bindings[&signing_share.index]);
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signer_commitment.hiding + (signer_commitment.binding * bindings[&signing_share.id]);
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signing_share.check_is_valid(&signer_pubkey, lambda_i, commitment_i, challenge)?;
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}
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@ -719,9 +716,9 @@ mod tests {
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if j == i {
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continue;
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}
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num *= Scalar::from(shares[j].receiver_index as u64);
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den *= Scalar::from(shares[j].receiver_index as u64)
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- Scalar::from(shares[i].receiver_index as u64);
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num *= Scalar::from(shares[j].receiver_id as u64);
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den *= Scalar::from(shares[j].receiver_id as u64)
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- Scalar::from(shares[i].receiver_id as u64);
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}
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if den == Scalar::zero() {
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return Err("Duplicate shares provided");
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@ -19,8 +19,8 @@ fn check_sign_with_dealer() {
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for share in &shares {
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// Generate one (1) nonce and one SigningCommitments instance for each
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// participant, up to _threshold_.
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let (nonce, commitment) = frost::preprocess(1, share.index, &mut rng);
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nonces.insert(share.index, nonce);
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let (nonce, commitment) = frost::preprocess(1, share.id, &mut rng);
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nonces.insert(share.id, nonce);
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commitments.push(commitment[0]);
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}
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@ -35,10 +35,10 @@ fn check_sign_with_dealer() {
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};
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// Round 2: each participant generates their signature share
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for (participant_index, nonce) in nonces {
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for (participant_id, nonce) in nonces {
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let share_package = shares
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.iter()
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.find(|share| participant_index == share.index)
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.find(|share| participant_id == share.id)
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.unwrap();
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let nonce_to_use = nonce[0];
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// Each participant generates their signature share.
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