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3.4.3 Merge the nonce calculation from DLEqProof and MultiDLEqProof into a

Browse source 
single function

3.4.3 actually describes getting rid of DLEqProof for a thin wrapper around
MultiDLEqProof. That can't be done due to DLEqProof not requiring the std
features, enabling Vecs, which MultiDLEqProof relies on.

Merging the verification statement does simplify the code a bit. While merging
the proof could also be, it has much less value due to the simplicity of
proving (nonce * G, scalar * G).
This commit is contained in:
Luke Parker 2023-02-24 05:11:01 -05:00
parent 6104d606be
commit 65376e93e5
No known key found for this signature in database
1 changed files with 19 additions and 12 deletions
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31
crypto/dleq/src/lib.rs
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@ -140,6 +140,21 @@ impl<G: PrimeGroup> DLEqProof<G> {
DLEqProof { c, s }
}
// Transcript a specific generator/nonce/point (G/R/A), as used when verifying a proof.
// This takes in the generator/point, and then the challenge and solution to calculate the nonce.
fn verify_statement<T: Transcript>(
transcript: &mut T,
generator: G,
point: G,
c: G::Scalar,
s: G::Scalar,
) {
// s = r + ca
// sG - cA = R
// R, A
Self::transcript(transcript, generator, (generator * s) - (point * c), point);
}
/// Verify the specified points share a discrete logarithm across the specified generators.
pub fn verify<T: Transcript>(
&self,
@ -153,10 +168,7 @@ impl<G: PrimeGroup> DLEqProof<G> {
transcript.domain_separate(b"dleq");
for (generator, point) in generators.iter().zip(points) {
// s = r + ca
// sG - cA = R
// R, A
Self::transcript(transcript, *generator, (*generator * self.s) - (*point * self.c), *point);
Self::verify_statement(transcript, *generator, *point, self.c, self.s);
}
if self.c != challenge(transcript) {
@ -212,7 +224,7 @@ impl<G: PrimeGroup> MultiDLEqProof<G> {
where
G::Scalar: Zeroize,
{
transcript.domain_separate(b"multi-dleq");
transcript.domain_separate(b"multi_dleq");
let mut nonces = vec![];
for (i, (scalar, generators)) in scalars.iter().zip(generators).enumerate() {
@ -256,7 +268,7 @@ impl<G: PrimeGroup> MultiDLEqProof<G> {
Err(DLEqError::InvalidProof)?;
}
transcript.domain_separate(b"multi-dleq");
transcript.domain_separate(b"multi_dleq");
for (i, (generators, points)) in generators.iter().zip(points).enumerate() {
if points.len() != generators.len() {
Err(DLEqError::InvalidProof)?;
@ -264,12 +276,7 @@ impl<G: PrimeGroup> MultiDLEqProof<G> {
transcript.append_message(b"discrete_logarithm", i.to_le_bytes());
for (generator, point) in generators.iter().zip(points) {
DLEqProof::transcript(
transcript,
*generator,
(*generator * self.s[i]) - (*point * self.c),
*point,
);
DLEqProof::verify_statement(transcript, *generator, *point, self.c, self.s[i]);
}
}