tbls: replace verifier with pubshares (#604)

Refactors tbls to use pubshares from start and remove verifier from the workflow.

category: refactor
ticket: #596

cluster/cluster_test.go

@@ -99,16 +99,8 @@ func TestEncode(t *testing.T) {
 		Validators: []cluster.DistValidator{
 			{
 				PubKey: testutil.RandomETHAddress(),
-				Verifiers: [][]byte{
-					testutil.RandomBytes32(),
-					testutil.RandomBytes32(),
-				},
 			}, {
 				PubKey: testutil.RandomETHAddress(),
-				Verifiers: [][]byte{
-					testutil.RandomBytes32(),
-					testutil.RandomBytes32(),
-				},
 			},
 		},
 	}

cluster/distvalidator.go

@@ -32,10 +32,6 @@ type DistValidator struct {
 	// It can be used to verify a partial signature created by any node in the cluster.
 	PubShares [][]byte `json:"public_shares,omitempty"`
 
-	// Verifiers are the threshold verifier commitments.
-	// Deprecated: Use PubShares.
-	Verifiers [][]byte `json:"threshold_verifiers,omitempty"`
-
 	// FeeRecipientAddress Ethereum address override for this validator, defaults to definition withdrawal address.
 	FeeRecipientAddress string `json:"fee_recipient_address,omitempty"`
 }
@@ -52,9 +48,9 @@ func (v DistValidator) HashTreeRootWith(hh *ssz.Hasher) error {
 	// Field (0) 'PubKey'
 	hh.PutBytes([]byte(v.PubKey))
 
-	for _, verifier := range v.Verifiers {
-		// Field (1+i) 'Verifier'
-		hh.PutBytes(verifier)
+	for _, pubshare := range v.PubShares {
+		// Field (1+i) 'Pubshare'
+		hh.PutBytes(pubshare)
 	}
 
 	// Field (N) 'FeeRecipientAddress'

cluster/test_cluster.go

@@ -65,15 +65,9 @@ func NewForT(t *testing.T, dv, k, n, seed int) (Lock, []*ecdsa.PrivateKey, [][]*
 		pk, err := tss.PublicKey().MarshalBinary()
 		require.NoError(t, err)
 
-		var verifiers [][]byte
-		for _, commitment := range tss.Verifier().Commitments {
-			verifiers = append(verifiers, commitment.ToAffineCompressed())
-		}
-
 		var pubshares [][]byte
 		for i := 0; i < n; i++ {
-			share, err := tss.PublicShare(i + 1) // Share indexes are 1-indexed.
-			require.NoError(t, err)
+			share := tss.PublicShare(i + 1) // Share indexes are 1-indexed.
 
 			b, err := share.MarshalBinary()
 			require.NoError(t, err)
@@ -84,7 +78,6 @@ func NewForT(t *testing.T, dv, k, n, seed int) (Lock, []*ecdsa.PrivateKey, [][]*
 		vals = append(vals, DistValidator{
 			PubKey:    fmt.Sprintf("%#x", pk),
 			PubShares: pubshares,
-			Verifiers: verifiers,
 		})
 		dvShares = append(dvShares, shares)
 	}

cluster/testdata/TestEncode_lock_json.golden

@@ -31,20 +31,12 @@
  },
  "distributed_validators": [
   {
-   "distributed_public_key": "0x7b182e046410f44bc4b0f3f03a0d06820a30f257",
-   "threshold_verifiers": [
-    "NCyLgFXEZtiGRB0lmQbWms2JS5aK6fDrnZZc5qRpPE4=",
-    "vogVAbfZhGtm6wK1flzae2y6aJHWFr1obDe4NGE6yLo="
-   ]
+   "distributed_public_key": "0x7b182e046410f44bc4b0f3f03a0d06820a30f257"
   },
   {
-   "distributed_public_key": "0xa22c008ffe688352734ae4e3f1217acd5f832708",
-   "threshold_verifiers": [
-    "eVeydxnOPzGI3+V97r9vgllaEPe7ViygTVw9J5QpWMY=",
-    "2zJiZwZJ87yX2aIxZzXt5oKl3+bxoBH7yYrQ++eQADw="
-   ]
+   "distributed_public_key": "0x342c8b8055c466d886441d259906d69acd894b96"
   }
  ],
  "signature_aggregate": "bbXBREw6NNMqXEp/++jRgfftO4z+kE+T+PBtKbzZ7YQ=",
- "lock_hash": "wcS2qPDhSo0jvYr6tM+7pk4H+nsglA/cf8+baqBnuK0="
+ "lock_hash": "c1GjLXPvkrYyXHyyATXvQ64yEjCcc/YmXl4PrK5MeDQ="
 }

cluster/testdata/TestEncode_lock_yaml.golden

@@ -23,12 +23,6 @@ cluster_definition:
   - otcjnEC0WsOVDZQfxP4cDLlq0yLWIoIpX7/hHiakMwc=
 distributed_validators:
 - distributed_public_key: "0x7b182e046410f44bc4b0f3f03a0d06820a30f257"
-  threshold_verifiers:
-  - NCyLgFXEZtiGRB0lmQbWms2JS5aK6fDrnZZc5qRpPE4=
-  - vogVAbfZhGtm6wK1flzae2y6aJHWFr1obDe4NGE6yLo=
-- distributed_public_key: "0xa22c008ffe688352734ae4e3f1217acd5f832708"
-  threshold_verifiers:
-  - eVeydxnOPzGI3+V97r9vgllaEPe7ViygTVw9J5QpWMY=
-  - 2zJiZwZJ87yX2aIxZzXt5oKl3+bxoBH7yYrQ++eQADw=
+- distributed_public_key: "0x342c8b8055c466d886441d259906d69acd894b96"
 signature_aggregate: bbXBREw6NNMqXEp/++jRgfftO4z+kE+T+PBtKbzZ7YQ=
-lock_hash: wcS2qPDhSo0jvYr6tM+7pk4H+nsglA/cf8+baqBnuK0=
+lock_hash: c1GjLXPvkrYyXHyyATXvQ64yEjCcc/YmXl4PrK5MeDQ=

cmd/createcluster.go

@@ -337,10 +337,7 @@ func newLock(conf clusterConfig, dvs []tbls.TSS, peers []p2p.Peer) (cluster.Lock
 
 		var pubshares [][]byte
 		for i := 0; i < dv.NumShares(); i++ {
-			share, err := dv.PublicShare(i + 1) // Shares are 1-indexed.
-			if err != nil {
-				return cluster.Lock{}, err
-			}
+			share := dv.PublicShare(i + 1) // Shares are 1-indexed.
 			b, err := share.MarshalBinary()
 			if err != nil {
 				return cluster.Lock{}, errors.Wrap(err, "marshal pubshare")

core/validatorapi/validatorapi_test.go

@@ -626,8 +626,7 @@ func TestComponent_ProposerDuties(t *testing.T) {
 
 	// Create keys (just use normal keys, not split tbls)
 	pubkey := tss.PublicKey()
-	pubshare, err := tss.PublicShare(vIdx)
-	require.NoError(t, err)
+	pubshare := tss.PublicShare(vIdx)
 
 	eth2Share, err := tblsconv.KeyToETH2(pubshare)
 	require.NoError(t, err)

dkg/dkg.go

@@ -328,12 +328,9 @@ func aggLockHashSig(data map[core.PubKey][]core.ParSignedData, shares map[core.P
 			var pubshare *bls_sig.PublicKey
 			switch dkgAlgo {
 			case "keycast":
-				pubshare, err = tbls.GetPubShare(s.ShareIdx, shares[pk].Verifier)
-				if err != nil {
-					return nil, nil, errors.Wrap(err, "get pubshare from verifier")
-				}
+				pubshare = shares[pk].PublicShares[s.ShareIdx]
 			case "frost":
-				pubshare = shares[pk].PublicShares[uint32(s.ShareIdx)]
+				pubshare = shares[pk].PublicShares[s.ShareIdx]
 			default:
 				return nil, nil, errors.New("invalid dkg algo")
 			}
@@ -493,7 +490,6 @@ func dvsFromShares(shares []share) ([]cluster.DistValidator, error) {
 
 		dvs = append(dvs, cluster.DistValidator{
 			PubKey:    fmt.Sprintf("%#x", msg.PubKey),
-			Verifiers: msg.Verifiers,
 			PubShares: msg.PubShares,
 		})
 	}

dkg/frost.go

@@ -219,7 +219,7 @@ func makeShares(
 	targetID uint32,
 ) ([]share, error) {
 	// Get set of public shares for each validator.
-	pubShares := make(map[uint32]map[uint32]*bls_sig.PublicKey) // map[ValIdx]map[SourceID]*bls_sig.PublicKey
+	pubShares := make(map[uint32]map[int]*bls_sig.PublicKey) // map[ValIdx]map[SourceID]*bls_sig.PublicKey
 	for key, result := range r2Result {
 		if key.TargetID != targetID {
 			// Not for us.
@@ -232,10 +232,10 @@ func makeShares(
 
 		m, ok := pubShares[key.ValIdx]
 		if !ok {
-			m = make(map[uint32]*bls_sig.PublicKey)
+			m = make(map[int]*bls_sig.PublicKey)
 			pubShares[key.ValIdx] = m
 		}
-		m[key.SourceID] = pubShare
+		m[int(key.SourceID)] = pubShare
 	}
 
 	// Sort shares by vIdx

dkg/keycast.go

@@ -21,8 +21,6 @@ import (
 	"io"
 	"sort"
 
-	"github.com/coinbase/kryptology/pkg/core/curves"
-	"github.com/coinbase/kryptology/pkg/sharing"
 	"github.com/coinbase/kryptology/pkg/signatures/bls/bls_sig"
 
 	"github.com/obolnetwork/charon/app/errors"
@@ -46,16 +44,13 @@ type share struct {
 	PubKey      *bls_sig.PublicKey
 	SecretShare *bls_sig.SecretKeyShare
 
-	// One of the two below will be populated,
-	Verifier     *sharing.FeldmanVerifier
-	PublicShares map[uint32]*bls_sig.PublicKey // map[shareIdx]*bls_sig.PublicKey
+	PublicShares map[int]*bls_sig.PublicKey // map[shareIdx]*bls_sig.PublicKey
 }
 
 // shareMsg is the share message wire format sent by the dealer.
 type shareMsg struct {
 	PubKey      []byte
 	PubShares   [][]byte
-	Verifiers   [][]byte
 	SecretShare []byte
 }
 
@@ -169,12 +164,7 @@ func leadKeyCast(ctx context.Context, tp kcTransport, def cluster.Definition, ra
 func createShares(numValidators, numNodes, threshold int, random io.Reader) ([][]share, error) {
 	resp := make([][]share, numNodes)
 	for i := 0; i < numValidators; i++ {
-		pubkey, secret, err := tbls.Keygen()
-		if err != nil {
-			return nil, err
-		}
-
-		shares, verifier, err := tbls.SplitSecret(secret, threshold, numNodes, random)
+		tss, shares, err := tbls.GenerateTSS(threshold, numNodes, random)
 		if err != nil {
 			return nil, err
 		}
@@ -185,9 +175,9 @@ func createShares(numValidators, numNodes, threshold int, random io.Reader) ([][
 
 		for ni := 0; ni < numNodes; ni++ {
 			resp[ni] = append(resp[ni], share{
-				PubKey:      pubkey,
-				Verifier:    verifier,
-				SecretShare: shares[ni],
+				PubKey:       tss.PublicKey(),
+				PublicShares: tss.PublicShares(),
+				SecretShare:  shares[ni],
 			})
 		}
 	}
@@ -202,13 +192,6 @@ func msgFromShare(s share) (shareMsg, error) {
 		return shareMsg{}, errors.Wrap(err, "marshal pubkey")
 	}
 
-	var verifiers [][]byte
-	if s.Verifier != nil {
-		for _, commitment := range s.Verifier.Commitments {
-			verifiers = append(verifiers, commitment.ToAffineCompressed())
-		}
-	}
-
 	// Sort pub shares by id/index.
 	var pubSharesIDs []int
 	for id := range s.PublicShares {
@@ -218,7 +201,7 @@ func msgFromShare(s share) (shareMsg, error) {
 
 	var pubShares [][]byte
 	for _, id := range pubSharesIDs {
-		b, err := s.PublicShares[uint32(id)].MarshalBinary()
+		b, err := s.PublicShares[id].MarshalBinary()
 		if err != nil {
 			return shareMsg{}, errors.Wrap(err, "marshal public share")
 		}
@@ -232,7 +215,6 @@ func msgFromShare(s share) (shareMsg, error) {
 
 	return shareMsg{
 		PubKey:      pubkey,
-		Verifiers:   verifiers,
 		SecretShare: secretShare,
 		PubShares:   pubShares,
 	}, nil
@@ -245,24 +227,14 @@ func shareFromMsg(msg shareMsg) (share, error) {
 		return share{}, errors.Wrap(err, "unmarshal pubkey")
 	}
 
-	var commitments []curves.Point
-	for _, v := range msg.Verifiers {
-		c, err := curves.BLS12381G1().Point.FromAffineCompressed(v)
-		if err != nil {
-			return share{}, errors.Wrap(err, "verifier hex")
-		}
-
-		commitments = append(commitments, c)
-	}
-
-	pubShares := make(map[uint32]*bls_sig.PublicKey)
+	pubShares := make(map[int]*bls_sig.PublicKey)
 	for id, bytes := range msg.PubShares {
 		pubShare := new(bls_sig.PublicKey)
 		if err := pubShare.UnmarshalBinary(bytes); err != nil {
 			return share{}, errors.Wrap(err, "unmarshal public share")
 		}
 
-		pubShares[uint32(id+1)] = pubShare // Public shares IDs are 1-indexed.
+		pubShares[id+1] = pubShare // Public shares IDs are 1-indexed.
 	}
 
 	secretShare := new(bls_sig.SecretKeyShare)
@@ -272,7 +244,6 @@ func shareFromMsg(msg shareMsg) (share, error) {
 
 	return share{
 		PubKey:       pubKey,
-		Verifier:     &sharing.FeldmanVerifier{Commitments: commitments},
 		SecretShare:  secretShare,
 		PublicShares: pubShares,
 	}, nil

tbls/tss.go

@@ -60,18 +60,14 @@ func KeygenWithSeed(reader io.Reader) (*bls_sig.PublicKey, *bls_sig.SecretKey, e
 // TSS (threshold signing scheme) wraps PubKey (PublicKey), Verifiers (the coefficients of the public polynomial)
 // and threshold (number of shares).
 type TSS struct {
-	verifier  *share.FeldmanVerifier
+	pubshares map[int]*bls_sig.PublicKey
 	numShares int
+	threshold int
 
 	// publicKey inferred from verifier commitments in NewTSS.
 	publicKey *bls_sig.PublicKey
 }
 
-// Verifier returns the feldman verifier containing the public shares of the threshold signature scheme.
-func (t TSS) Verifier() *share.FeldmanVerifier {
-	return t.verifier
-}
-
 // NumShares returns the number of shares in the threshold signature scheme.
 func (t TSS) NumShares() int {
 	return t.numShares
@@ -84,12 +80,16 @@ func (t TSS) PublicKey() *bls_sig.PublicKey {
 
 // Threshold returns the minimum number of partial signatures required to aggregate the threshold signature.
 func (t TSS) Threshold() int {
-	return len(t.verifier.Commitments)
+	return t.threshold
 }
 
 // PublicShare returns a share's public key by share index (identifier).
-func (t TSS) PublicShare(shareIdx int) (*bls_sig.PublicKey, error) {
-	return GetPubShare(shareIdx, t.verifier)
+func (t TSS) PublicShare(shareIdx int) *bls_sig.PublicKey {
+	return t.pubshares[shareIdx]
+}
+
+func (t TSS) PublicShares() map[int]*bls_sig.PublicKey {
+	return t.pubshares
 }
 
 func NewTSS(verifier *share.FeldmanVerifier, numShares int) (TSS, error) {
@@ -99,10 +99,19 @@ func NewTSS(verifier *share.FeldmanVerifier, numShares int) (TSS, error) {
 		return TSS{}, errors.Wrap(err, "unmarshal pubkey")
 	}
 
+	pubshares := make(map[int]*bls_sig.PublicKey)
+	for i := 1; i <= numShares; i++ {
+		pubshares[i], err = getPubShare(i, verifier)
+		if err != nil {
+			return TSS{}, err
+		}
+	}
+
 	return TSS{
-		verifier:  verifier,
+		pubshares: pubshares,
 		publicKey: pk,
 		numShares: numShares,
+		threshold: len(verifier.Commitments),
 	}, nil
 }
 
@@ -153,10 +162,7 @@ func VerifyAndAggregate(tss TSS, partialSigs []*bls_sig.PartialSignature, msg []
 
 	for _, psig := range partialSigs {
 		// TODO(dhruv): add break condition if valid shares >= threshold
-		pubShare, err := tss.PublicShare(int(psig.Identifier))
-		if err != nil {
-			return nil, nil, errors.Wrap(err, "get Public Share")
-		}
+		pubShare := tss.PublicShare(int(psig.Identifier))
 
 		sig := &bls_sig.Signature{Value: psig.Signature}
 		ok, err := blsScheme.Verify(pubShare, msg, sig)
@@ -247,8 +253,8 @@ func SplitSecret(secret *bls_sig.SecretKey, t, n int, reader io.Reader) ([]*bls_
 	return sks, verifier, nil
 }
 
-// GetPubShare returns the public key share for the i'th/identifier/shareIdx share from the verifier commitments.
-func GetPubShare(identifier int, verifier *share.FeldmanVerifier) (*bls_sig.PublicKey, error) {
+// getPubShare returns the public key share for the i'th/identifier/shareIdx share from the verifier commitments.
+func getPubShare(identifier int, verifier *share.FeldmanVerifier) (*bls_sig.PublicKey, error) {
 	curve := curves.GetCurveByName(verifier.Commitments[0].CurveName())
 	if curve != curves.BLS12381G1() {
 		return nil, errors.New("curve mismatch")

tbls/tss_test.go

@@ -53,8 +53,7 @@ func TestAggregateSignatures(t *testing.T) {
 
 		partialSigs[i] = psig
 
-		pubshare, err := tss.PublicShare(int(psig.Identifier))
-		require.NoError(t, err)
+		pubshare := tss.PublicShare(int(psig.Identifier))
 
 		ok, err := tbls.Verify(pubshare, msg, &bls_sig.Signature{Value: psig.Signature})
 		require.NoError(t, err)