add tests

Signed-off-by: bytemare <3641580+bytemare@users.noreply.github.com>

commitment.go

@@ -96,7 +96,7 @@ func (c CommitmentList) Participants() []uint64 {
 	return out
 }
 
-// ParticipantsScalar returns the group.Scalar list of participant identifier in the list
+// ParticipantsScalar returns the group.Scalar list of participant identifier in the list.
 func (c CommitmentList) ParticipantsScalar() []*group.Scalar {
 	if len(c) == 0 {
 		return nil
@@ -321,11 +321,11 @@ func (c *Configuration) validateCommitmentListLength(commitments CommitmentList)
 }
 
 // ValidateCommitmentList returns an error if at least one of the following conditions is not met:
-// - list length is within [threshold;max]
-// - no signer identifier in commitments is 0
-// - no singer identifier in commitments is > max signers
-// - no duplicated in signer identifiers
-// - all commitment signer identifiers are registered in the configuration
+// - list length is within [threshold;max].
+// - no signer identifier in commitments is 0.
+// - no singer identifier in commitments is > max signers.
+// - no duplicated in signer identifiers.
+// - all commitment signer identifiers are registered in the configuration.
 func (c *Configuration) ValidateCommitmentList(commitments CommitmentList) error {
 	if !c.verified || !c.keysVerified {
 		if err := c.Init(); err != nil {

encoding.go

@@ -46,6 +46,7 @@ func encodedLength(encID byte, g group.Group, other ...uint64) uint64 {
 	case encConf:
 		return 1 + 3*8 + eLen + other[0]
 	case encSigner:
+		_ = other[3]
 		return other[0] + 2 + 2 + 2 + other[1] + other[2] + other[3]
 	case encSigShare:
 		return 1 + 8 + sLen

frost.go

@@ -231,7 +231,8 @@ func (c *Configuration) ValidateKeyShare(keyShare *KeyShare) error {
 
 	if pk.Equal(keyShare.PublicKey) != 1 {
 		return errors.New(
-			"provided key share has a different public key than the one registered for that signer in the configuration",
+			"provided key share has a different public key than" +
+				"the one registered for that signer in the configuration",
 		)
 	}
 

internal/lambda.go

@@ -19,9 +19,9 @@ import (
 
 // Lambda derives the interpolating value for id in the polynomial made by the participant identifiers.
 // This function assumes that:
-// - id is non-nil and != 0
-// - every scalar in participants is non-nil and != 0
-// - there are no duplicates in participants
+// - id is non-nil and != 0.
+// - every scalar in participants is non-nil and != 0.
+// - there are no duplicates in participants.
 func Lambda(g group.Group, id uint64, participants []*group.Scalar) *group.Scalar {
 	sid := g.NewScalar().SetUInt64(id)
 	numerator := g.NewScalar().One()
@@ -39,6 +39,8 @@ func Lambda(g group.Group, id uint64, participants []*group.Scalar) *group.Scala
 	return numerator.Multiply(denominator.Invert())
 }
 
+// LambdaRegistry holds a signers pre-computed lambda values, indexed by the list of participants they are associated
+// to. A sorted set of participants will yield the same lambda.
 type LambdaRegistry map[string]*group.Scalar
 
 const lambdaRegistryKeyDomainSeparator = "FROST-participants"
@@ -50,9 +52,9 @@ func lambdaRegistryKey(participants []uint64) string {
 
 // New creates a new lambda and for the participant list for the participant id, and registers it.
 // This function assumes that:
-// - id is non-nil and != 0
-// - every participant id is != 0
-// - there are no duplicates in participants
+// - id is non-nil and != 0.
+// - every participant id is != 0.
+// - there are no duplicates in participants.
 func (l LambdaRegistry) New(g group.Group, id uint64, participants []uint64) *group.Scalar {
 	polynomial := secretsharing.NewPolynomialFromListFunc(g, participants, func(p uint64) *group.Scalar {
 		return g.NewScalar().SetUInt64(p)
@@ -63,11 +65,14 @@ func (l LambdaRegistry) New(g group.Group, id uint64, participants []uint64) *gr
 	return lambda
 }
 
+// Get returns the recorded lambda for the list of participants, or nil if it wasn't found.
 func (l LambdaRegistry) Get(participants []uint64) *group.Scalar {
 	key := lambdaRegistryKey(participants)
 	return l[key]
 }
 
+// GetOrNew returns the recorded lambda for the list of participants, or created, records, and returns a new one if
+// it wasn't found.
 func (l LambdaRegistry) GetOrNew(g group.Group, id uint64, participants []uint64) *group.Scalar {
 	lambda := l.Get(participants)
 	if lambda == nil {
@@ -77,17 +82,20 @@ func (l LambdaRegistry) GetOrNew(g group.Group, id uint64, participants []uint64
 	return lambda
 }
 
+// Set records lambda for the given set of participants.
 func (l LambdaRegistry) Set(participants []uint64, lambda *group.Scalar) {
 	key := lambdaRegistryKey(participants)
 	l[key] = lambda
 }
 
+// Delete deletes the lambda for the given set of participants.
 func (l LambdaRegistry) Delete(participants []uint64) {
 	key := lambdaRegistryKey(participants)
 	l[key].Zero()
 	delete(l, key)
 }
 
+// Decode populates the receiver from the byte encoded serialization in data.
 func (l LambdaRegistry) Decode(g group.Group, data []byte) error {
 	offset := 0
 	for offset < len(data) {

tests/commitment_test.go

@@ -17,14 +17,35 @@ import (
 	"github.com/bytemare/frost"
 )
 
+func TestCommitment_Validate_InvalidConfiguration(t *testing.T) {
+	expectedErrorPrefix := "invalid group public key, the key is nil"
+	tt := &tableTest{
+		Ciphersuite: frost.Ristretto255,
+		threshold:   3,
+		maxSigners:  5,
+	}
+	configuration := &frost.Configuration{
+		Ciphersuite:           tt.Ciphersuite,
+		Threshold:             tt.threshold,
+		MaxSigners:            tt.maxSigners,
+		GroupPublicKey:        nil,
+		SignerPublicKeyShares: nil,
+	}
+
+	if err := configuration.ValidateCommitment(nil); err == nil ||
+		!strings.HasPrefix(err.Error(), expectedErrorPrefix) {
+		t.Fatalf("expected %q, got %q", expectedErrorPrefix, err)
+	}
+}
+
 func TestCommitment_Validate_NilCommitment(t *testing.T) {
 	expectedErrorPrefix := "the commitment list has a nil commitment"
 	tt := &tableTest{
 		Ciphersuite: frost.Ristretto255,
 		threshold:   3,
 		maxSigners:  4,
 	}
-	configuration, _ := fullSetup(t, tt)
+	configuration := makeConf(t, tt)
 
 	if err := configuration.ValidateCommitment(nil); err == nil ||
 		!strings.HasPrefix(err.Error(), expectedErrorPrefix) {
@@ -231,6 +252,27 @@ func TestCommitmentList_Sort(t *testing.T) {
 	})
 }
 
+func TestCommitmentList_Validate_InvalidConfiguration(t *testing.T) {
+	expectedErrorPrefix := "invalid group public key, the key is nil"
+	tt := &tableTest{
+		Ciphersuite: frost.Ristretto255,
+		threshold:   3,
+		maxSigners:  5,
+	}
+	configuration := &frost.Configuration{
+		Ciphersuite:           tt.Ciphersuite,
+		Threshold:             tt.threshold,
+		MaxSigners:            tt.maxSigners,
+		GroupPublicKey:        nil,
+		SignerPublicKeyShares: nil,
+	}
+
+	if err := configuration.ValidateCommitmentList(nil); err == nil ||
+		!strings.HasPrefix(err.Error(), expectedErrorPrefix) {
+		t.Fatalf("expected %q, got %q", expectedErrorPrefix, err)
+	}
+}
+
 func TestCommitmentList_Validate_NoCommitments(t *testing.T) {
 	expectedErrorPrefix := "commitment list is empty"
 	tt := &tableTest{
@@ -345,6 +387,28 @@ func TestCommitmentList_Validate_InvalidCommitment(t *testing.T) {
 	}
 }
 
+func TestCommitmentList_Validate_NilCommitment(t *testing.T) {
+	expectedErrorPrefix := "the commitment list has a nil commitment"
+	tt := &tableTest{
+		Ciphersuite: frost.Ristretto255,
+		threshold:   3,
+		maxSigners:  4,
+	}
+	configuration, signers := fullSetup(t, tt)
+	coms := make(frost.CommitmentList, len(signers))
+
+	for i, s := range signers {
+		coms[i] = s.Commit()
+	}
+
+	coms[2] = nil
+
+	if err := configuration.ValidateCommitmentList(coms); err == nil ||
+		!strings.HasPrefix(err.Error(), expectedErrorPrefix) {
+		t.Fatalf("expected %q, got %q", expectedErrorPrefix, err)
+	}
+}
+
 func TestCommitmentList_Validate_NotSorted(t *testing.T) {
 	expectedErrorPrefix := "commitment list is not sorted by signer identifiers"
 	tt := &tableTest{

tests/encoding_test.go

@@ -374,7 +374,7 @@ func TestEncoding_Configuration_InvalidGroupPublicKey(t *testing.T) {
 	})
 }
 
-func TestEncoding_Configuration_InvalidPublicKeyShare(t *testing.T) {
+func TestEncoding_Configuration_BadPublicKeyShare(t *testing.T) {
 	expectedErrorPrefix := "could not decode signer public key share for signer 1: "
 
 	testAll(t, func(t *testing.T, test *tableTest) {
@@ -407,6 +407,35 @@ func TestEncoding_Configuration_InvalidPublicKeyShare(t *testing.T) {
 	})
 }
 
+func TestEncoding_Configuration_InvalidPublicKeyShares(t *testing.T) {
+	expectedErrorPrefix := "invalid number of public keys (lower than threshold or above maximum)"
+
+	testAll(t, func(t *testing.T, test *tableTest) {
+		keyShares, groupPublicKey, _ := debug.TrustedDealerKeygen(
+			test.Ciphersuite,
+			nil,
+			test.threshold,
+			test.maxSigners,
+		)
+		publicKeyShares := getPublicKeyShares(keyShares)
+
+		configuration := &frost.Configuration{
+			Ciphersuite:           test.Ciphersuite,
+			Threshold:             test.threshold,
+			MaxSigners:            test.maxSigners,
+			GroupPublicKey:        groupPublicKey,
+			SignerPublicKeyShares: publicKeyShares,
+		}
+		configuration.SignerPublicKeyShares = configuration.SignerPublicKeyShares[:test.threshold-1]
+		encoded := configuration.Encode()
+
+		decoded := new(frost.Configuration)
+		if err := decoded.Decode(encoded); err == nil || !strings.HasPrefix(err.Error(), expectedErrorPrefix) {
+			t.Fatalf("expected %q, got %q", expectedErrorPrefix, err)
+		}
+	})
+}
+
 func TestEncoding_Configuration_CantVerify_InvalidPubKey(t *testing.T) {
 	expectedErrorPrefix := "invalid group public key, the key is the group generator (base element)"