diff --git a/go/tdh2/lib/group/nist/curve.go b/go/tdh2/lib/group/nist/curve.go
index 9da4915..f90d2f8 100644
--- a/go/tdh2/lib/group/nist/curve.go
+++ b/go/tdh2/lib/group/nist/curve.go
@@ -38,12 +38,12 @@ func (p *curvePoint) Equal(p2 group.Point) bool {
 	// Make sure both coordinates are normalized.
 	// Apparently Go's elliptic curve code doesn't always ensure this.
 	M := p.c.p.P
-	p.x.Mod(p.x, M)
-	p.y.Mod(p.y, M)
-	cp2.x.Mod(cp2.x, M)
-	cp2.y.Mod(cp2.y, M)
+	x1 := new(big.Int).Mod(p.x, M)
+	y1 := new(big.Int).Mod(p.y, M)
+	x2 := new(big.Int).Mod(cp2.x, M)
+	y2 := new(big.Int).Mod(cp2.y, M)
 
-	return p.x.Cmp(cp2.x) == 0 && p.y.Cmp(cp2.y) == 0
+	return x1.Cmp(x2) == 0 && y1.Cmp(y2) == 0
 }
 
 func (p *curvePoint) Null() group.Point {
@@ -134,6 +134,8 @@ func (p *curvePoint) UnmarshalBinary(buf []byte) error {
 		if p.x == nil || !p.Valid() {
 			return errors.New("invalid elliptic curve point")
 		}
+	} else if buf[0] != 0x04 {
+		return errors.New("invalid elliptic curve point: non-canonical identity encoding")
 	} else {
 		// All bytes are 0, so we initialize x and y
 		p.x = big.NewInt(0)
diff --git a/go/tdh2/tdh2easy/tdh2easy.go b/go/tdh2/tdh2easy/tdh2easy.go
index 132b800..1c38c33 100644
--- a/go/tdh2/tdh2easy/tdh2easy.go
+++ b/go/tdh2/tdh2easy/tdh2easy.go
@@ -117,7 +117,7 @@ func (m *MasterSecret) Unmarshal(data []byte) error {
 	return m.m.Unmarshal(data)
 }
 
-func (m MasterSecret) UnmarshalJSON(data []byte) error {
+func (m *MasterSecret) UnmarshalJSON(data []byte) error {
 	return m.Unmarshal(data)
 }
 
diff --git a/go/tdh2/tdh2easy/tdh2easy_test.go b/go/tdh2/tdh2easy/tdh2easy_test.go
index 07121ba..023c09c 100644
--- a/go/tdh2/tdh2easy/tdh2easy_test.go
+++ b/go/tdh2/tdh2easy/tdh2easy_test.go
@@ -58,6 +58,27 @@ func TestPrivateShareMarshal(t *testing.T) {
 	}
 }
 
+func TestPrivateShareMarshalJSON(t *testing.T) {
+	_, _, want, err := GenerateKeys(2, 3)
+	if err != nil {
+		t.Fatalf("GenerateKeys: %v", err)
+	}
+	b, err := want[0].MarshalJSON()
+	if err != nil {
+		t.Fatalf("MarshalJSON: %v", err)
+	}
+	var got PrivateShare
+	if err := got.UnmarshalJSON(b); err != nil {
+		t.Fatalf("UnmarshalJSON: %v", err)
+	}
+	if !reflect.DeepEqual(got.p, want[0].p) {
+		t.Errorf("got=%v want=%v", got, want[0])
+	}
+	if err := got.UnmarshalJSON([]byte("broken")); err == nil {
+		t.Errorf("Unmarshal did not fail")
+	}
+}
+
 func TestDecryptionShareMarshal(t *testing.T) {
 	_, pk, sh, err := GenerateKeys(2, 3)
 	if err != nil {
@@ -87,6 +108,35 @@ func TestDecryptionShareMarshal(t *testing.T) {
 	}
 }
 
+func TestDecryptionShareMarshalJSON(t *testing.T) {
+	_, pk, sh, err := GenerateKeys(2, 3)
+	if err != nil {
+		t.Fatalf("GenerateKeys: %v", err)
+	}
+	c, err := Encrypt(pk, []byte("msg"))
+	if err != nil {
+		t.Fatalf("Encrypt: %v", err)
+	}
+	want, err := Decrypt(c, sh[0])
+	if err != nil {
+		t.Fatalf("Decrypt: %v", err)
+	}
+	b, err := want.MarshalJSON()
+	if err != nil {
+		t.Fatalf("MarshalJSON: %v", err)
+	}
+	var got DecryptionShare
+	if err := got.UnmarshalJSON(b); err != nil {
+		t.Fatalf("UnmarshalJSON: %v", err)
+	}
+	if !reflect.DeepEqual(got.d, want.d) {
+		t.Errorf("got=%v want=%v", got, want)
+	}
+	if err := got.UnmarshalJSON([]byte("broken")); err == nil {
+		t.Errorf("UnmarshalJSON did not fail")
+	}
+}
+
 func TestPublicKeyMarshal(t *testing.T) {
 	_, want, _, err := GenerateKeys(2, 3)
 	if err != nil {
@@ -108,6 +158,27 @@ func TestPublicKeyMarshal(t *testing.T) {
 	}
 }
 
+func TestPublicKeyMarshalJSON(t *testing.T) {
+	_, want, _, err := GenerateKeys(2, 3)
+	if err != nil {
+		t.Fatalf("GenerateKeys: %v", err)
+	}
+	b, err := want.MarshalJSON()
+	if err != nil {
+		t.Fatalf("MarshalJSON: %v", err)
+	}
+	var got PublicKey
+	if err := got.UnmarshalJSON(b); err != nil {
+		t.Fatalf("UnmarshalJSON: %v", err)
+	}
+	if !got.p.Equal(want.p) {
+		t.Errorf("got=%v want=%v", got, want)
+	}
+	if err := got.UnmarshalJSON([]byte("broken")); err == nil {
+		t.Errorf("UnmarshalJSON did not fail")
+	}
+}
+
 func TestMasterSecretMarshal(t *testing.T) {
 	want, _, _, err := GenerateKeys(2, 3)
 	if err != nil {
@@ -129,6 +200,27 @@ func TestMasterSecretMarshal(t *testing.T) {
 	}
 }
 
+func TestMasterSecretMarshalJSON(t *testing.T) {
+	want, _, _, err := GenerateKeys(2, 3)
+	if err != nil {
+		t.Fatalf("GenerateKeys: %v", err)
+	}
+	b, err := want.MarshalJSON()
+	if err != nil {
+		t.Fatalf("MarshalJSON: %v", err)
+	}
+	var got MasterSecret
+	if err := got.UnmarshalJSON(b); err != nil {
+		t.Fatalf("UnmarshalJSON: %v", err)
+	}
+	if !reflect.DeepEqual(got.m, want.m) {
+		t.Errorf("got=%v want=%v", got, want)
+	}
+	if err := got.UnmarshalJSON([]byte("broken")); err == nil {
+		t.Errorf("UnmarshalJSON did not fail")
+	}
+}
+
 func TestCiphertextDecrypt(t *testing.T) {
 	_, pk, share, err := GenerateKeys(1, 1)
 	if err != nil {