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Clean and optimise the aggregate_expiration_signatures function

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This commit is contained in:
aniampio
2023-11-21 17:37:55 +00:00
parent 45739442d6
commit a977af65f9
1 changed files with 31 additions and 38 deletions
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common/nym_offline_compact_ecash/src/scheme/expiration_date_signatures.rs
+31 -38
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@@ -74,45 +74,41 @@ pub fn aggregate_expiration_signatures(
indices: &[u64],
vkeys: &[VerificationKeyAuth],
signatures: &[PartialExpirationDateSignature]) -> Result<Vec<ExpirationDateSignature>>{
// check if we have enough unique partial signatures to meet the required threshold
if !(indices.iter().unique_by(|&index| index).count() == indices.len()){
// Check if vkeys and signatures have the same length
if vkeys.len() != signatures.len() {
return Err(CompactEcashError::ExpirationDate(
"Mismatched lengths of vkeys and signatures".to_string(),
));
}
// Check if we have enough unique partial signatures to meet the required threshold
if indices.iter().unique_by(|&index| index).count() != indices.len() {
return Err(CompactEcashError::ExpirationDate(
"Not enough unique indices shares".to_string(),
));
}
// evaluate at 0 the Lagrange basis polynomials k_i
// Evaluate at 0 the Lagrange basis polynomials k_i
let coefficients = generate_lagrangian_coefficients_at_origin(indices);
let mut exp_date_signs: Vec<ExpirationDateSignature> = Vec::new();
for l in 0..params.L() {
let m0: u64 = expiration_date;
let m1: u64 = expiration_date - constants::VALIDITY_PERIOD + l;
let m2 = constants::TYPE_EXP;
let m0_bytes: [u8; 8] = m0.to_le_bytes();
let m1_bytes: [u8; 8] = m1.to_le_bytes();
let m0_scalar = Scalar::from(m0);
let m1_scalar = Scalar::from(m1);
let m2_scalar = Scalar::from_bytes(&m2).unwrap();
let mut concatenated_attributes = Vec::new();
concatenated_attributes.extend_from_slice(&m0_bytes);
concatenated_attributes.extend_from_slice(&m1_bytes);
let m0: Scalar = Scalar::from(expiration_date);
let m1: Scalar = Scalar::from(expiration_date - constants::VALIDITY_PERIOD + l);
let m2: Scalar = Scalar::from_bytes(&constants::TYPE_EXP).unwrap();
// Compute the hash
let h = hash_g1(concatenated_attributes);
let h = hash_g1([m0.to_bytes(), m1.to_bytes(), m2.to_bytes()].concat());
// Verify each partial signature
for (vkey, sig) in vkeys.iter().zip(signatures.iter()) {
if sig.h != h {
// return Err(CompactEcashError::ExpirationDate(
// "Failed to verify the commitment hash".to_string(),
// ));
return Err(CompactEcashError::ExpirationDate(
"Failed to verify the commitment hash".to_string(),
));
}
// Verify the signature correctness
let partially_signed_attributes = [m0_scalar, m1_scalar, m2_scalar]
let partially_signed_attributes = [m0, m1, m2]
.iter()
.zip(vkey.beta_g2.iter())
.map(|(m, beta_i)| beta_i * Scalar::from(*m))
@@ -124,39 +120,36 @@ pub fn aggregate_expiration_signatures(
&sig.s.to_affine(),
params.grp().prepared_miller_g2(),
) {
// return Err(CompactEcashError::ExpirationDate(
// "Verification of the partial expiration date signature failed".to_string(),
// ));
return Err(CompactEcashError::ExpirationDate(
"Verification of the partial expiration date signature failed".to_string(),
));
}
}
// compute the aggregated signature of the expiration date
let aggr_s: G1Projective = coefficients.clone()
.into_iter()
// Compute the aggregated signature of the expiration date
let aggr_s: G1Projective = coefficients
.iter()
.zip(signatures.iter())
.map(|(coeff, sig)| sig.s * coeff)
.sum();
let aggr_sig = ExpirationDateSignature{
h : signatures[0].h,
s : aggr_s,
};
let aggr_sig = ExpirationDateSignature { h, s: aggr_s };
let signed_attributes = [m0_scalar, m1_scalar, m2_scalar]
let signed_attributes = [m0, m1, m2]
.iter()
.zip(vk_auth.beta_g2.iter())
.map(|(m, beta_i)| beta_i * Scalar::from(*m))
.sum::<G2Projective>();
// check validity of the aggregated signature
// Check the validity of the aggregated signature
if !check_bilinear_pairing(
&aggr_sig.h.to_affine(),
&G2Prepared::from((vk_auth.alpha + signed_attributes).to_affine()),
&aggr_sig.s.to_affine(),
params.grp().prepared_miller_g2(),
) {
// return Err(CompactEcashError::ExpirationDate(
// "Verification of the aggregated expiration date signature failed".to_string(),
// ));
return Err(CompactEcashError::ExpirationDate(
"Verification of the aggregated expiration date signature failed".to_string(),
));
}
exp_date_signs.push(aggr_sig);
}