tbls: refactor tss struct for testing (#136)

Refactors the tbls.TSS struct to allow for arbitrary data during testing. This allows using know existing validator public keys when testing the scheduler, ensuring that duties that we calculate match those in mainnet.

category: refactor
ticket: #145

tbls/tss.go

@@ -40,22 +40,26 @@ type PubShare struct {
 type TSS struct {
 	Verifier  *share.FeldmanVerifier
 	NumShares int
-}
 
-// Threshold returns the secret sharing threshold.
-func (t TSS) Threshold() int {
-	return len(t.Verifier.Commitments)
+	// PublicKey and Threshold are inferred from verifier commitments in NewTSS.
+
+	PublicKey *bls_sig.PublicKey
+	Threshold int
 }
 
-// PublicKey returns the root public key for given verifiers.
-func (t TSS) PublicKey() (*bls_sig.PublicKey, error) {
-	pk := &bls_sig.PublicKey{}
-	err := pk.UnmarshalBinary(t.Verifier.Commitments[0].ToAffineCompressed())
+func NewTSS(verifier *share.FeldmanVerifier, numShares int) (TSS, error) {
+	pk := new(bls_sig.PublicKey)
+	err := pk.UnmarshalBinary(verifier.Commitments[0].ToAffineCompressed())
 	if err != nil {
-		return nil, errors.Wrap(err, "unmarshal pubkey")
+		return TSS{}, errors.Wrap(err, "unmarshal pubkey")
 	}
 
-	return pk, nil
+	return TSS{
+		Verifier:  verifier,
+		PublicKey: pk,
+		NumShares: numShares,
+		Threshold: len(verifier.Commitments),
+	}, nil
 }
 
 // GenerateTSS returns a new random instance of threshold signing scheme and associated SecretKeyShares.
@@ -73,14 +77,18 @@ func GenerateTSS(t, n int, reader io.Reader) (TSS, []*bls_sig.SecretKeyShare, er
 		return TSS{}, nil, errors.Wrap(err, "generate secret shares")
 	}
 
-	return TSS{Verifier: verifier, NumShares: n}, sks, nil
+	tss, err := NewTSS(verifier, n)
+	if err != nil {
+		return TSS{}, nil, err
+	}
+
+	return tss, sks, nil
 }
 
 // AggregateSignatures aggregates partial signatures over the given message.
 // Returns aggregated signatures and slice of signers identifiers that had valid partial signatures.
 func AggregateSignatures(tss TSS, partialSigs []*bls_sig.PartialSignature, msg []byte) (*bls_sig.Signature, []byte, error) {
-	threshold := tss.Threshold()
-	if len(partialSigs) < threshold {
+	if len(partialSigs) < tss.Threshold {
 		return nil, nil, errors.New("insufficient signatures")
 	}
 
@@ -105,7 +113,7 @@ func AggregateSignatures(tss TSS, partialSigs []*bls_sig.PartialSignature, msg [
 		signers = append(signers, psig.Identifier)
 	}
 
-	if len(validShares) < threshold {
+	if len(validShares) < tss.Threshold {
 		return nil, nil, errors.New("insufficient valid signatures")
 	}
 

tbls/tss_test.go

@@ -33,7 +33,7 @@ func TestGenerateTSS(t *testing.T) {
 	require.NotNil(t, tss)
 	require.NotNil(t, secrets)
 
-	require.Equal(t, threshold, tss.Threshold())
+	require.Equal(t, threshold, tss.Threshold)
 	require.Equal(t, shares, tss.NumShares)
 }
 
@@ -58,9 +58,7 @@ func TestAggregateSignatures(t *testing.T) {
 	sig, _, err := tbls.AggregateSignatures(tss, partialSigs, msg)
 	require.NoError(t, err)
 
-	pubkey, err := tss.PublicKey()
-	require.NoError(t, err)
-	result, err := tbls.Verify(pubkey, msg, sig)
+	result, err := tbls.Verify(tss.PublicKey, msg, sig)
 	require.NoError(t, err)
 	require.Equal(t, true, result)
 }

types/manifest.go

@@ -122,12 +122,7 @@ func (m Manifest) MarshalJSON() ([]byte, error) {
 			verifiers = append(verifiers, c.ToAffineCompressed())
 		}
 
-		pk, err := tss.PublicKey()
-		if err != nil {
-			return nil, errors.Wrap(err, "get pubkey")
-		}
-
-		rawPK, err := pk.MarshalBinary()
+		rawPK, err := tss.PublicKey.MarshalBinary()
 		if err != nil {
 			return nil, errors.Wrap(err, "marshal pubkey")
 		}
@@ -198,12 +193,15 @@ func (m *Manifest) UnmarshalJSON(data []byte) error {
 			commitments = append(commitments, c)
 		}
 
-		dvs = append(dvs, tbls.TSS{
-			Verifier: &sharing.FeldmanVerifier{
-				Commitments: commitments,
-			},
-			NumShares: len(mjson.PeerENRs),
-		})
+		tss, err := tbls.NewTSS(
+			&sharing.FeldmanVerifier{Commitments: commitments},
+			len(mjson.PeerENRs),
+		)
+		if err != nil {
+			return err
+		}
+
+		dvs = append(dvs, tss)
 	}
 
 	*m = Manifest{
@@ -259,7 +257,7 @@ func getDescription(m Manifest) string {
 
 	var threshold int
 	if dv > 0 {
-		threshold = m.DVs[0].Threshold()
+		threshold = m.DVs[0].Threshold
 	}
 
 	return fmt.Sprintf("dv/%d/threshold/%d/peer/%d", dv, threshold, peers)

types/manifest_test.go

@@ -69,11 +69,7 @@ func TestManifestJSON(t *testing.T) {
 			tss2 := manifest2.DVs[i]
 			require.Equal(t, tss1.NumShares, tss2.NumShares)
 			require.Equal(t, tss1.Verifier, tss2.Verifier)
-			pk1, err := tss1.PublicKey()
-			require.NoError(t, err)
-			pk2, err := tss2.PublicKey()
-			require.NoError(t, err)
-			require.Equal(t, pk1, pk2)
+			require.Equal(t, tss1.PublicKey, tss2.PublicKey)
 		}
 	}
 }