Remove DLEq proofs from CLSAG multisig

1) Removes the key image DLEq on the Monero side of things, as the produced
   signature share serves as a DLEq for it.
2) Removes the nonce DLEqs from modular-frost as they're unnecessary for
   monero-serai. Updates documentation accordingly.

Without the proof the nonces are internally consistent, the produced signatures
from modular-frost can be argued as a batch-verifiable CP93 DLEq (R0, R1, s),
or as a GSP for the CP93 DLEq statement (which naturally produces (R0, R1, s)).

The lack of proving the nonces consistent does make the process weaker, yet
it's also unnecessary for the class of protocols this is intended to service.
To provide DLEqs for the nonces would be to provide PoKs for the nonce
commitments (in the traditional Schnorr case).

Cargo.lock

@@ -4642,7 +4642,6 @@ dependencies = [
  "dalek-ff-group",
  "digest 0.10.7",
  "dkg",
- "dleq",
  "flexible-transcript",
  "hex",
  "minimal-ed448",
@@ -4679,7 +4678,6 @@ dependencies = [
  "curve25519-dalek",
  "dalek-ff-group",
  "digest_auth",
- "dleq",
  "flexible-transcript",
  "group",
  "hex",

coins/monero/Cargo.toml

@@ -43,7 +43,6 @@ multiexp = { path = "../../crypto/multiexp", version = "0.4", default-features =
 
 # Needed for multisig
 transcript = { package = "flexible-transcript", path = "../../crypto/transcript", version = "0.3", default-features = false, features = ["recommended"], optional = true }
-dleq = { path = "../../crypto/dleq", version = "0.4", default-features = false, features = ["serialize"], optional = true }
 frost = { package = "modular-frost", path = "../../crypto/frost", version = "0.8", default-features = false, features = ["ed25519"], optional = true }
 
 monero-generators = { path = "generators", version = "0.4", default-features = false }
@@ -91,7 +90,6 @@ std = [
   "multiexp/std",
 
   "transcript/std",
-  "dleq/std",
 
   "monero-generators/std",
 
@@ -106,7 +104,7 @@ std = [
 
 cache-distribution = ["async-lock"]
 http-rpc = ["digest_auth", "simple-request", "tokio"]
-multisig = ["transcript", "frost", "dleq", "std"]
+multisig = ["transcript", "frost", "std"]
 binaries = ["tokio/rt-multi-thread", "tokio/macros", "http-rpc"]
 experimental = []
 

coins/monero/src/ringct/clsag/mod.rs

@@ -27,8 +27,6 @@ use crate::{
 mod multisig;
 #[cfg(feature = "multisig")]
 pub use multisig::{ClsagDetails, ClsagAddendum, ClsagMultisig};
-#[cfg(feature = "multisig")]
-pub(crate) use multisig::add_key_image_share;
 
 /// Errors returned when CLSAG signing fails.
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
@@ -279,8 +277,10 @@ impl Clsag {
         nonce.deref() *
           hash_to_point(&inputs[i].2.decoys.ring[usize::from(inputs[i].2.decoys.i)][0]),
       );
-      clsag.s[usize::from(inputs[i].2.decoys.i)] =
+      // Effectively r - cx, except cx is (c_p x) + (c_c z), where z is the delta between a ring
-        (-((p * inputs[i].0.deref()) + c)) + nonce.deref();
+      // member's commitment and our input commitment (which will only have a known discrete log
+      // over G if the amounts cancel out)
+      clsag.s[usize::from(inputs[i].2.decoys.i)] = nonce.deref() - ((p * inputs[i].0.deref()) + c);
       inputs[i].0.zeroize();
       nonce.zeroize();
 

coins/monero/src/ringct/clsag/multisig.rs

@@ -1,5 +1,8 @@
 use core::{ops::Deref, fmt::Debug};
-use std_shims::io::{self, Read, Write};
+use std_shims::{
+  io::{self, Read, Write},
+  collections::HashMap,
+};
 use std::sync::{Arc, RwLock};
 
 use rand_core::{RngCore, CryptoRng, SeedableRng};
@@ -9,11 +12,13 @@ use zeroize::{Zeroize, ZeroizeOnDrop, Zeroizing};
 
 use curve25519_dalek::{scalar::Scalar, edwards::EdwardsPoint};
 
-use group::{ff::Field, Group, GroupEncoding};
+use group::{
+  ff::{Field, PrimeField},
+  Group, GroupEncoding,
+};
 
 use transcript::{Transcript, RecommendedTranscript};
 use dalek_ff_group as dfg;
-use dleq::DLEqProof;
 use frost::{
   dkg::lagrange,
   curve::Ed25519,
@@ -26,10 +31,6 @@ use crate::ringct::{
   clsag::{ClsagInput, Clsag},
 };
 
-fn dleq_transcript() -> RecommendedTranscript {
-  RecommendedTranscript::new(b"monero_key_image_dleq")
-}
-
 impl ClsagInput {
   fn transcript<T: Transcript>(&self, transcript: &mut T) {
     // Doesn't domain separate as this is considered part of the larger CLSAG proof
@@ -43,6 +44,7 @@ impl ClsagInput {
       // They're just a unreliable reference to this data which will be included in the message
       // if in use
       transcript.append_message(b"member", [u8::try_from(i).expect("ring size exceeded 255")]);
+      // This also transcripts the key image generator since it's derived from this key
       transcript.append_message(b"key", pair[0].compress().to_bytes());
       transcript.append_message(b"commitment", pair[1].compress().to_bytes())
     }
@@ -70,13 +72,11 @@ impl ClsagDetails {
 #[derive(Clone, PartialEq, Eq, Zeroize, Debug)]
 pub struct ClsagAddendum {
   pub(crate) key_image: dfg::EdwardsPoint,
-  dleq: DLEqProof<dfg::EdwardsPoint>,
 }
 
 impl WriteAddendum for ClsagAddendum {
   fn write<W: Write>(&self, writer: &mut W) -> io::Result<()> {
-    writer.write_all(self.key_image.compress().to_bytes().as_ref())?;
+    writer.write_all(self.key_image.compress().to_bytes().as_ref())
-    self.dleq.write(writer)
   }
 }
 
@@ -97,9 +97,8 @@ pub struct ClsagMultisig {
   transcript: RecommendedTranscript,
 
   pub(crate) H: EdwardsPoint,
-  // Merged here as CLSAG needs it, passing it would be a mess, yet having it beforehand requires
+  key_image_shares: HashMap<[u8; 32], dfg::EdwardsPoint>,
-  // an extra round
+  image: Option<dfg::EdwardsPoint>,
-  image: EdwardsPoint,
 
   details: Arc<RwLock<Option<ClsagDetails>>>,
 
@@ -117,7 +116,8 @@ impl ClsagMultisig {
       transcript,
 
       H: hash_to_point(&output_key),
-      image: EdwardsPoint::identity(),
+      key_image_shares: HashMap::new(),
+      image: None,
 
       details,
 
@@ -135,20 +135,6 @@ impl ClsagMultisig {
   }
 }
 
-pub(crate) fn add_key_image_share(
-  image: &mut EdwardsPoint,
-  generator: EdwardsPoint,
-  offset: Scalar,
-  included: &[Participant],
-  participant: Participant,
-  share: EdwardsPoint,
-) {
-  if image.is_identity().into() {
-    *image = generator * offset;
-  }
-  *image += share * lagrange::<dfg::Scalar>(participant, included).0;
-}
-
 impl Algorithm<Ed25519> for ClsagMultisig {
   type Transcript = RecommendedTranscript;
   type Addendum = ClsagAddendum;
@@ -160,23 +146,10 @@ impl Algorithm<Ed25519> for ClsagMultisig {
 
   fn preprocess_addendum<R: RngCore + CryptoRng>(
     &mut self,
-    rng: &mut R,
+    _rng: &mut R,
     keys: &ThresholdKeys<Ed25519>,
   ) -> ClsagAddendum {
-    ClsagAddendum {
+    ClsagAddendum { key_image: dfg::EdwardsPoint(self.H) * keys.secret_share().deref() }
-      key_image: dfg::EdwardsPoint(self.H) * keys.secret_share().deref(),
-      dleq: DLEqProof::prove(
-        rng,
-        // Doesn't take in a larger transcript object due to the usage of this
-        // Every prover would immediately write their own DLEq proof, when they can only do so in
-        // the proper order if they want to reach consensus
-        // It'd be a poor API to have CLSAG define a new transcript solely to pass here, just to
-        // try to merge later in some form, when it should instead just merge xH (as it does)
-        &mut dleq_transcript(),
-        &[dfg::EdwardsPoint::generator(), dfg::EdwardsPoint(self.H)],
-        keys.secret_share(),
-      ),
-    }
   }
 
   fn read_addendum<R: Read>(&self, reader: &mut R) -> io::Result<ClsagAddendum> {
@@ -190,7 +163,7 @@ impl Algorithm<Ed25519> for ClsagMultisig {
       Err(io::Error::other("non-canonical key image"))?;
     }
 
-    Ok(ClsagAddendum { key_image: xH, dleq: DLEqProof::<dfg::EdwardsPoint>::read(reader)? })
+    Ok(ClsagAddendum { key_image: xH })
   }
 
   fn process_addendum(
@@ -199,33 +172,29 @@ impl Algorithm<Ed25519> for ClsagMultisig {
     l: Participant,
     addendum: ClsagAddendum,
   ) -> Result<(), FrostError> {
-    // TODO: This check is faulty if two shares are additive inverses of each other
+    if self.image.is_none() {
-    if self.image.is_identity().into() {
       self.transcript.domain_separate(b"CLSAG");
+      // Transcript the ring
       self.input().transcript(&mut self.transcript);
+      // Transcript the mask
       self.transcript.append_message(b"mask", self.mask().to_bytes());
+
+      // Init the image to the offset
+      self.image = Some(dfg::EdwardsPoint(self.H) * view.offset());
     }
 
+    // Transcript this participant's contribution
     self.transcript.append_message(b"participant", l.to_bytes());
-
-    addendum
-      .dleq
-      .verify(
-        &mut dleq_transcript(),
-        &[dfg::EdwardsPoint::generator(), dfg::EdwardsPoint(self.H)],
-        &[view.original_verification_share(l), addendum.key_image],
-      )
-      .map_err(|_| FrostError::InvalidPreprocess(l))?;
-
     self.transcript.append_message(b"key_image_share", addendum.key_image.compress().to_bytes());
-    add_key_image_share(
+
-      &mut self.image,
+    // Accumulate the interpolated share
-      self.H,
+    let interpolated_key_image_share =
-      view.offset().0,
+      addendum.key_image * lagrange::<dfg::Scalar>(l, view.included());
-      view.included(),
+    *self.image.as_mut().unwrap() += interpolated_key_image_share;
-      l,
+
-      addendum.key_image.0,
+    self
-    );
+      .key_image_shares
+      .insert(view.verification_share(l).to_bytes(), interpolated_key_image_share);
 
     Ok(())
   }
@@ -253,7 +222,7 @@ impl Algorithm<Ed25519> for ClsagMultisig {
     #[allow(non_snake_case)]
     let (clsag, pseudo_out, p, c) = Clsag::sign_core(
       &mut rng,
-      &self.image,
+      &self.image.expect("verifying a share despite never processing any addendums").0,
       &self.input(),
       self.mask(),
       self.msg.as_ref().unwrap(),
@@ -262,7 +231,8 @@ impl Algorithm<Ed25519> for ClsagMultisig {
     );
     self.interim = Some(Interim { p, c, clsag, pseudo_out });
 
-    (-(dfg::Scalar(p) * view.secret_share().deref())) + nonces[0].deref()
+    // r - p x, where p is the challenge for the keys
+    *nonces[0] - dfg::Scalar(p) * view.secret_share().deref()
   }
 
   #[must_use]
@@ -274,11 +244,13 @@ impl Algorithm<Ed25519> for ClsagMultisig {
   ) -> Option<Self::Signature> {
     let interim = self.interim.as_ref().unwrap();
     let mut clsag = interim.clsag.clone();
+    // We produced shares as `r - p x`, yet the signature is `r - p x - c x`
+    // Substract `c x` (saved as `c`) now
     clsag.s[usize::from(self.input().decoys.i)] = sum.0 - interim.c;
     if clsag
       .verify(
         &self.input().decoys.ring,
-        &self.image,
+        &self.image.expect("verifying a signature despite never processing any addendums").0,
         &interim.pseudo_out,
         self.msg.as_ref().unwrap(),
       )
@@ -296,10 +268,61 @@ impl Algorithm<Ed25519> for ClsagMultisig {
     share: dfg::Scalar,
   ) -> Result<Vec<(dfg::Scalar, dfg::EdwardsPoint)>, ()> {
     let interim = self.interim.as_ref().unwrap();
-    Ok(vec![
+
+    // For a share `r - p x`, the following two equalities should hold:
+    // - `(r - p x)G == R.0 - pV`, where `V = xG`
+    // - `(r - p x)H == R.1 - pK`, where `K = xH` (the key image share)
+    //
+    // This is effectively a discrete log equality proof for:
+    // V, K over G, H
+    // with nonces
+    // R.0, R.1
+    // and solution
+    // s
+    //
+    // Which is a batch-verifiable rewrite of the traditional CP93 proof
+    // (and also writable as Generalized Schnorr Protocol)
+    //
+    // That means that given a proper challenge, this alone can be certainly argued to prove the
+    // key image share is well-formed and the provided signature so proves for that.
+
+    // This is a bit funky as it doesn't prove the nonces are well-formed however. They're part of
+    // the prover data/transcript for a CP93/GSP proof, not part of the statement. This practically
+    // is fine, for a variety of reasons (given a consistent `x`, a consistent `r` can be
+    // extracted, and the nonces as used in CLSAG are also part of its prover data/transcript).
+
+    let key_image_share = self.key_image_shares[&verification_share.to_bytes()];
+
+    // Hash every variable relevant here, using the hahs output as the random weight
+    let mut weight_transcript =
+      RecommendedTranscript::new(b"monero-serai v0.1 ClsagMultisig::verify_share");
+    weight_transcript.append_message(b"G", dfg::EdwardsPoint::generator().to_bytes());
+    weight_transcript.append_message(b"H", self.H.to_bytes());
+    weight_transcript.append_message(b"xG", verification_share.to_bytes());
+    weight_transcript.append_message(b"xH", key_image_share.to_bytes());
+    weight_transcript.append_message(b"rG", nonces[0][0].to_bytes());
+    weight_transcript.append_message(b"rH", nonces[0][1].to_bytes());
+    weight_transcript.append_message(b"c", dfg::Scalar(interim.p).to_repr());
+    weight_transcript.append_message(b"s", share.to_repr());
+    let weight = weight_transcript.challenge(b"weight");
+    let weight = dfg::Scalar(Scalar::from_bytes_mod_order_wide(&weight.into()));
+
+    let part_one = vec![
       (share, dfg::EdwardsPoint::generator()),
-      (dfg::Scalar(interim.p), verification_share),
+      // -(R.0 - pV) == -R.0 + pV
       (-dfg::Scalar::ONE, nonces[0][0]),
-    ])
+      (dfg::Scalar(interim.p), verification_share),
+    ];
+
+    let mut part_two = vec![
+      (weight * share, dfg::EdwardsPoint(self.H)),
+      // -(R.1 - pK) == -R.1 + pK
+      (-weight, nonces[0][1]),
+      (weight * dfg::Scalar(interim.p), key_image_share),
+    ];
+
+    let mut all = part_one;
+    all.append(&mut part_two);
+    Ok(all)
   }
 }

coins/monero/src/wallet/send/multisig.rs

@@ -18,6 +18,7 @@ use transcript::{Transcript, RecommendedTranscript};
 use frost::{
   curve::Ed25519,
   Participant, FrostError, ThresholdKeys,
+  dkg::lagrange,
   sign::{
     Writable, Preprocess, CachedPreprocess, SignatureShare, PreprocessMachine, SignMachine,
     SignatureMachine, AlgorithmMachine, AlgorithmSignMachine, AlgorithmSignatureMachine,
@@ -27,7 +28,7 @@ use frost::{
 use crate::{
   random_scalar,
   ringct::{
-    clsag::{ClsagInput, ClsagDetails, ClsagAddendum, ClsagMultisig, add_key_image_share},
+    clsag::{ClsagInput, ClsagDetails, ClsagAddendum, ClsagMultisig},
     RctPrunable,
   },
   transaction::{Input, Transaction},
@@ -261,8 +262,13 @@ impl SignMachine<Transaction> for TransactionSignMachine {
     included.push(self.i);
     included.sort_unstable();
 
-    // Convert the unified commitments to a Vec of the individual commitments
+    // Start calculating the key images, as needed on the TX level
     let mut images = vec![EdwardsPoint::identity(); self.clsags.len()];
+    for (image, (generator, offset)) in images.iter_mut().zip(&self.key_images) {
+      *image = generator * offset;
+    }
+
+    // Convert the serialized nonces commitments to a parallelized Vec
     let mut commitments = (0 .. self.clsags.len())
       .map(|c| {
         included
@@ -291,14 +297,7 @@ impl SignMachine<Transaction> for TransactionSignMachine {
             // provides the easiest API overall, as this is where the TX is (which needs the key
             // images in its message), along with where the outputs are determined (where our
             // outputs may need these in order to guarantee uniqueness)
-            add_key_image_share(
+            images[c] += preprocess.addendum.key_image.0 * lagrange::<dfg::Scalar>(*l, &included).0;
-              &mut images[c],
-              self.key_images[c].0,
-              self.key_images[c].1,
-              &included,
-              *l,
-              preprocess.addendum.key_image.0,
-            );
 
             Ok((*l, preprocess))
           })

crypto/frost/Cargo.toml

@@ -38,7 +38,6 @@ ciphersuite = { path = "../ciphersuite", version = "^0.4.1", default-features =
 multiexp = { path = "../multiexp", version = "0.4", default-features = false, features = ["std", "batch"] }
 
 schnorr = { package = "schnorr-signatures", path = "../schnorr", version = "^0.5.1", default-features = false, features = ["std"] }
-dleq = { path = "../dleq", version = "^0.4.1", default-features = false, features = ["std", "serialize"] }
 
 dkg = { path = "../dkg", version = "^0.5.1", default-features = false, features = ["std"] }
 

crypto/frost/src/algorithm.rs

@@ -39,6 +39,13 @@ pub trait Algorithm<C: Curve>: Send + Sync + Clone {
 
   /// Obtain the list of nonces to generate, as specified by the generators to create commitments
   /// against per-nonce.
+  ///
+  /// The Algorithm is responsible for all transcripting of these nonce specifications/generators.
+  ///
+  /// The prover will be passed the commitments, and the commitments will be sent to all other
+  /// participants. No guarantees the commitments are internally consistent (have the same discrete
+  /// logarithm across generators) are made. Any Algorithm which specifies multiple generators for
+  /// a single nonce must handle that itself.
   fn nonces(&self) -> Vec<Vec<C::G>>;
 
   /// Generate an addendum to FROST"s preprocessing stage.

crypto/frost/src/nonce.rs

@@ -1,13 +1,9 @@
 // FROST defines its nonce as sum(Di, Ei * bi)
-// Monero needs not just the nonce over G however, yet also over H
-// Then there is a signature (a modified Chaum Pedersen proof) using multiple nonces at once
 //
-// Accordingly, in order for this library to be robust, it supports generating an arbitrary amount
+// In order for this library to be robust, it supports generating an arbitrary amount of nonces,
-// of nonces, each against an arbitrary list of generators
+// each against an arbitrary list of generators
 //
 // Each nonce remains of the form (d, e) and made into a proper nonce with d + (e * b)
-// When representations across multiple generators are provided, a DLEq proof is also provided to
-// confirm their integrity
 
 use core::ops::Deref;
 use std::{
@@ -24,32 +20,8 @@ use transcript::Transcript;
 use ciphersuite::group::{ff::PrimeField, Group, GroupEncoding};
 use multiexp::multiexp_vartime;
 
-use dleq::MultiDLEqProof;
-
 use crate::{curve::Curve, Participant};
 
-// Transcript used to aggregate binomial nonces for usage within a single DLEq proof.
-fn aggregation_transcript<T: Transcript>(context: &[u8]) -> T {
-  let mut transcript = T::new(b"FROST DLEq Aggregation v0.5");
-  transcript.append_message(b"context", context);
-  transcript
-}
-
-// Every participant proves for their commitments at the start of the protocol
-// These proofs are verified sequentially, requiring independent transcripts
-// In order to make these transcripts more robust, the FROST transcript (at time of preprocess) is
-// challenged in order to create a commitment to it, carried in each independent transcript
-// (effectively forking the original transcript)
-//
-// For FROST, as defined by the IETF, this will do nothing (and this transcript will never even be
-// constructed). For higher level protocols, the transcript may have contextual info these proofs
-// will then be bound to
-fn dleq_transcript<T: Transcript>(context: &[u8]) -> T {
-  let mut transcript = T::new(b"FROST Commitments DLEq v0.5");
-  transcript.append_message(b"context", context);
-  transcript
-}
-
 // Each nonce is actually a pair of random scalars, notated as d, e under the FROST paper
 // This is considered a single nonce as r = d + be
 #[derive(Clone, Zeroize)]
@@ -69,7 +41,7 @@ impl<C: Curve> GeneratorCommitments<C> {
   }
 }
 
-// A single nonce's commitments and relevant proofs
+// A single nonce's commitments
 #[derive(Clone, PartialEq, Eq)]
 pub(crate) struct NonceCommitments<C: Curve> {
   // Called generators as these commitments are indexed by generator later on
@@ -121,12 +93,6 @@ impl<C: Curve> NonceCommitments<C> {
       t.append_message(b"commitment_E", commitments.0[1].to_bytes());
     }
   }
-
-  fn aggregation_factor<T: Transcript>(&self, context: &[u8]) -> C::F {
-    let mut transcript = aggregation_transcript::<T>(context);
-    self.transcript(&mut transcript);
-    <C as Curve>::hash_to_F(b"dleq_aggregation", transcript.challenge(b"binding").as_ref())
-  }
 }
 
 /// Commitments for all the nonces across all their generators.
@@ -135,51 +101,26 @@ pub(crate) struct Commitments<C: Curve> {
   // Called nonces as these commitments are indexed by nonce
   // So to get the commitments for the first nonce, it'd be commitments.nonces[0]
   pub(crate) nonces: Vec<NonceCommitments<C>>,
-  // DLEq Proof proving that each set of commitments were generated using a single pair of discrete
-  // logarithms
-  pub(crate) dleq: Option<MultiDLEqProof<C::G>>,
 }
 
 impl<C: Curve> Commitments<C> {
-  pub(crate) fn new<R: RngCore + CryptoRng, T: Transcript>(
+  pub(crate) fn new<R: RngCore + CryptoRng>(
     rng: &mut R,
     secret_share: &Zeroizing<C::F>,
     planned_nonces: &[Vec<C::G>],
-    context: &[u8],
   ) -> (Vec<Nonce<C>>, Commitments<C>) {
     let mut nonces = vec![];
     let mut commitments = vec![];
 
-    let mut dleq_generators = vec![];
-    let mut dleq_nonces = vec![];
     for generators in planned_nonces {
       let (nonce, these_commitments): (Nonce<C>, _) =
         NonceCommitments::new(&mut *rng, secret_share, generators);
 
-      if generators.len() > 1 {
-        dleq_generators.push(generators.clone());
-        dleq_nonces.push(Zeroizing::new(
-          (these_commitments.aggregation_factor::<T>(context) * nonce.0[1].deref()) +
-            nonce.0[0].deref(),
-        ));
-      }
-
       nonces.push(nonce);
       commitments.push(these_commitments);
     }
 
-    let dleq = if !dleq_generators.is_empty() {
+    (nonces, Commitments { nonces: commitments })
-      Some(MultiDLEqProof::prove(
-        rng,
-        &mut dleq_transcript::<T>(context),
-        &dleq_generators,
-        &dleq_nonces,
-      ))
-    } else {
-      None
-    };
-
-    (nonces, Commitments { nonces: commitments, dleq })
   }
 
   pub(crate) fn transcript<T: Transcript>(&self, t: &mut T) {
@@ -187,58 +128,20 @@ impl<C: Curve> Commitments<C> {
     for nonce in &self.nonces {
       nonce.transcript(t);
     }
-
-    // Transcripting the DLEqs implicitly transcripts the exact generators used for the nonces in
-    // an exact order
-    // This means it shouldn't be possible for variadic generators to cause conflicts
-    if let Some(dleq) = &self.dleq {
-      t.append_message(b"dleq", dleq.serialize());
-    }
   }
 
-  pub(crate) fn read<R: Read, T: Transcript>(
+  pub(crate) fn read<R: Read>(reader: &mut R, generators: &[Vec<C::G>]) -> io::Result<Self> {
-    reader: &mut R,
-    generators: &[Vec<C::G>],
-    context: &[u8],
-  ) -> io::Result<Self> {
     let nonces = (0 .. generators.len())
       .map(|i| NonceCommitments::read(reader, &generators[i]))
       .collect::<Result<Vec<NonceCommitments<C>>, _>>()?;
 
-    let mut dleq_generators = vec![];
+    Ok(Commitments { nonces })
-    let mut dleq_nonces = vec![];
-    for (generators, nonce) in generators.iter().cloned().zip(&nonces) {
-      if generators.len() > 1 {
-        let binding = nonce.aggregation_factor::<T>(context);
-        let mut aggregated = vec![];
-        for commitments in &nonce.generators {
-          aggregated.push(commitments.0[0] + (commitments.0[1] * binding));
-        }
-        dleq_generators.push(generators);
-        dleq_nonces.push(aggregated);
-      }
-    }
-
-    let dleq = if !dleq_generators.is_empty() {
-      let dleq = MultiDLEqProof::read(reader, dleq_generators.len())?;
-      dleq
-        .verify(&mut dleq_transcript::<T>(context), &dleq_generators, &dleq_nonces)
-        .map_err(|_| io::Error::other("invalid DLEq proof"))?;
-      Some(dleq)
-    } else {
-      None
-    };
-
-    Ok(Commitments { nonces, dleq })
   }
 
   pub(crate) fn write<W: Write>(&self, writer: &mut W) -> io::Result<()> {
     for nonce in &self.nonces {
       nonce.write(writer)?;
     }
-    if let Some(dleq) = &self.dleq {
-      dleq.write(writer)?;
-    }
     Ok(())
   }
 }

crypto/frost/src/sign.rs

@@ -125,14 +125,8 @@ impl<C: Curve, A: Algorithm<C>> AlgorithmMachine<C, A> {
     let mut params = self.params;
 
     let mut rng = ChaCha20Rng::from_seed(*seed.0);
-    // Get a challenge to the existing transcript for use when proving for the commitments
+    let (nonces, commitments) =
-    let commitments_challenge = params.algorithm.transcript().challenge(b"commitments");
+      Commitments::new::<_>(&mut rng, params.keys.secret_share(), &params.algorithm.nonces());
-    let (nonces, commitments) = Commitments::new::<_, A::Transcript>(
-      &mut rng,
-      params.keys.secret_share(),
-      &params.algorithm.nonces(),
-      commitments_challenge.as_ref(),
-    );
     let addendum = params.algorithm.preprocess_addendum(&mut rng, &params.keys);
 
     let preprocess = Preprocess { commitments, addendum };
@@ -141,27 +135,18 @@ impl<C: Curve, A: Algorithm<C>> AlgorithmMachine<C, A> {
     let mut blame_entropy = [0; 32];
     rng.fill_bytes(&mut blame_entropy);
     (
-      AlgorithmSignMachine {
+      AlgorithmSignMachine { params, seed, nonces, preprocess: preprocess.clone(), blame_entropy },
-        params,
-        seed,
-        commitments_challenge,
-        nonces,
-        preprocess: preprocess.clone(),
-        blame_entropy,
-      },
       preprocess,
     )
   }
 
   #[cfg(any(test, feature = "tests"))]
   pub(crate) fn unsafe_override_preprocess(
-    mut self,
+    self,
     nonces: Vec<Nonce<C>>,
     preprocess: Preprocess<C, A::Addendum>,
   ) -> AlgorithmSignMachine<C, A> {
     AlgorithmSignMachine {
-      commitments_challenge: self.params.algorithm.transcript().challenge(b"commitments"),
-
       params: self.params,
       seed: CachedPreprocess(Zeroizing::new([0; 32])),
 
@@ -255,8 +240,6 @@ pub struct AlgorithmSignMachine<C: Curve, A: Algorithm<C>> {
   params: Params<C, A>,
   seed: CachedPreprocess,
 
-  #[zeroize(skip)]
-  commitments_challenge: <A::Transcript as Transcript>::Challenge,
   pub(crate) nonces: Vec<Nonce<C>>,
   // Skips the preprocess due to being too large a bound to feasibly enforce on users
   #[zeroize(skip)]
@@ -285,11 +268,7 @@ impl<C: Curve, A: Algorithm<C>> SignMachine<A::Signature> for AlgorithmSignMachi
 
   fn read_preprocess<R: Read>(&self, reader: &mut R) -> io::Result<Self::Preprocess> {
     Ok(Preprocess {
-      commitments: Commitments::read::<_, A::Transcript>(
+      commitments: Commitments::read::<_>(reader, &self.params.algorithm.nonces())?,
-        reader,
-        &self.params.algorithm.nonces(),
-        self.commitments_challenge.as_ref(),
-      )?,
       addendum: self.params.algorithm.read_addendum(reader)?,
     })
   }

crypto/frost/src/tests/mod.rs

@@ -12,7 +12,7 @@ use crate::{
 
 /// Tests for the nonce handling code.
 pub mod nonces;
-use nonces::{test_multi_nonce, test_invalid_commitment, test_invalid_dleq_proof};
+use nonces::test_multi_nonce;
 
 /// Vectorized test suite to ensure consistency.
 pub mod vectors;
@@ -267,6 +267,4 @@ pub fn test_ciphersuite<R: RngCore + CryptoRng, C: Curve, H: Hram<C>>(rng: &mut
   test_schnorr_blame::<R, C, H>(rng);
 
   test_multi_nonce::<R, C>(rng);
-  test_invalid_commitment::<R, C>(rng);
-  test_invalid_dleq_proof::<R, C>(rng);
 }

crypto/frost/src/tests/nonces.rs

@@ -9,14 +9,12 @@ use transcript::{Transcript, RecommendedTranscript};
 
 use ciphersuite::group::{ff::Field, Group, GroupEncoding};
 
-use dleq::MultiDLEqProof;
 pub use dkg::tests::{key_gen, recover_key};
 
 use crate::{
   Curve, Participant, ThresholdView, ThresholdKeys, FrostError,
   algorithm::Algorithm,
-  sign::{Writable, SignMachine},
+  tests::{algorithm_machines, sign},
-  tests::{algorithm_machines, preprocess, sign},
 };
 
 #[derive(Clone)]
@@ -157,75 +155,3 @@ pub fn test_multi_nonce<R: RngCore + CryptoRng, C: Curve>(rng: &mut R) {
   let machines = algorithm_machines(&mut *rng, &MultiNonce::<C>::new(), &keys);
   sign(&mut *rng, &MultiNonce::<C>::new(), keys.clone(), machines, &[]);
 }
-
-/// Test malleating a commitment for a nonce across generators causes the preprocess to error.
-pub fn test_invalid_commitment<R: RngCore + CryptoRng, C: Curve>(rng: &mut R) {
-  let keys = key_gen::<R, C>(&mut *rng);
-  let machines = algorithm_machines(&mut *rng, &MultiNonce::<C>::new(), &keys);
-  let (machines, mut preprocesses) = preprocess(&mut *rng, machines, |_, _| {});
-
-  // Select a random participant to give an invalid commitment
-  let participants = preprocesses.keys().collect::<Vec<_>>();
-  let faulty = *participants
-    [usize::try_from(rng.next_u64() % u64::try_from(participants.len()).unwrap()).unwrap()];
-
-  // Grab their preprocess
-  let mut preprocess = preprocesses.remove(&faulty).unwrap();
-
-  // Mutate one of the commitments
-  let nonce =
-    preprocess.commitments.nonces.get_mut(usize::try_from(rng.next_u64()).unwrap() % 2).unwrap();
-  let generators_len = nonce.generators.len();
-  nonce.generators[usize::try_from(rng.next_u64()).unwrap() % generators_len].0
-    [usize::try_from(rng.next_u64()).unwrap() % 2] = C::G::random(&mut *rng);
-
-  // The commitments are validated at time of deserialization (read_preprocess)
-  // Accordingly, serialize it and read it again to make sure that errors
-  assert!(machines
-    .iter()
-    .next()
-    .unwrap()
-    .1
-    .read_preprocess::<&[u8]>(&mut preprocess.serialize().as_ref())
-    .is_err());
-}
-
-/// Test malleating the DLEq proof for a preprocess causes it to error.
-pub fn test_invalid_dleq_proof<R: RngCore + CryptoRng, C: Curve>(rng: &mut R) {
-  let keys = key_gen::<R, C>(&mut *rng);
-  let machines = algorithm_machines(&mut *rng, &MultiNonce::<C>::new(), &keys);
-  let (machines, mut preprocesses) = preprocess(&mut *rng, machines, |_, _| {});
-
-  // Select a random participant to give an invalid DLEq proof
-  let participants = preprocesses.keys().collect::<Vec<_>>();
-  let faulty = *participants
-    [usize::try_from(rng.next_u64() % u64::try_from(participants.len()).unwrap()).unwrap()];
-
-  // Invalidate it by replacing it with a completely different proof
-  let dlogs = [Zeroizing::new(C::F::random(&mut *rng)), Zeroizing::new(C::F::random(&mut *rng))];
-  let mut preprocess = preprocesses.remove(&faulty).unwrap();
-  preprocess.commitments.dleq = Some(MultiDLEqProof::prove(
-    &mut *rng,
-    &mut RecommendedTranscript::new(b"Invalid DLEq Proof"),
-    &nonces::<C>(),
-    &dlogs,
-  ));
-
-  assert!(machines
-    .iter()
-    .next()
-    .unwrap()
-    .1
-    .read_preprocess::<&[u8]>(&mut preprocess.serialize().as_ref())
-    .is_err());
-
-  // Also test None for a proof will cause an error
-  preprocess.commitments.dleq = None;
-  assert!(machines
-    .iter()
-    .next()
-    .unwrap()
-    .1
-    .read_preprocess::<&[u8]>(&mut preprocess.serialize().as_ref())
-    .is_err());
-}

crypto/frost/src/tests/vectors.rs

@@ -14,7 +14,7 @@ use ciphersuite::group::{ff::PrimeField, GroupEncoding};
 use crate::{
   curve::Curve,
   Participant, ThresholdCore, ThresholdKeys,
-  algorithm::{IetfTranscript, Hram, IetfSchnorr},
+  algorithm::{Hram, IetfSchnorr},
   sign::{
     Writable, Nonce, GeneratorCommitments, NonceCommitments, Commitments, Preprocess,
     PreprocessMachine, SignMachine, SignatureMachine, AlgorithmMachine,
@@ -191,7 +191,6 @@ pub fn test_with_vectors<R: RngCore + CryptoRng, C: Curve, H: Hram<C>>(
             nonces: vec![NonceCommitments {
               generators: vec![GeneratorCommitments(these_commitments)],
             }],
-            dleq: None,
           },
           addendum: (),
         };
@@ -301,12 +300,8 @@ pub fn test_with_vectors<R: RngCore + CryptoRng, C: Curve, H: Hram<C>>(
     }
 
     // Also test it at the Commitments level
-    let (generated_nonces, commitments) = Commitments::<C>::new::<_, IetfTranscript>(
+    let (generated_nonces, commitments) =
-      &mut TransparentRng(randomness),
+      Commitments::<C>::new::<_>(&mut TransparentRng(randomness), &share, &[vec![C::generator()]]);
-      &share,
-      &[vec![C::generator()]],
-      &[],
-    );
 
     assert_eq!(generated_nonces.len(), 1);
     assert_eq!(generated_nonces[0].0, [nonces[0].clone(), nonces[1].clone()]);