Merge pull request #38 from privacybydesign/add-method-for-legacy-key…

…share-protocol feat: add method to remove keyshare's P from ProofU for old keyshare protocol
privacybydesign · Dec 12, 2022 · 68a0869 · 68a0869
2 parents 8e9ce1f + a3226e8
commit 68a0869
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/legacy.go b/legacy.go
@@ -14,3 +14,11 @@ func KeyshareResponseLegacy(secret, commit, challenge *big.Int, key *gabikeys.Pu
 		SResponse: new(big.Int).Add(commit, new(big.Int).Mul(challenge, secret)),
 	}
 }
+
+func (p *ProofU) RemoveKeyshareP(b *CredentialBuilder) {
+	if b.keyshareP == nil {
+		return
+	}
+	p.U.Mul(p.U, new(big.Int).ModInverse(b.keyshareP, b.pk.N))
+	p.U.Mod(p.U, b.pk.N)
+}