Add Stringer & TextMarshaler interface

ristretto255.go

@@ -14,6 +14,7 @@ package ristretto255
 
 import (
 	"bytes"
+	"encoding/base64"
 	"errors"
 
 	"github.com/gtank/ristretto255/internal/edwards25519"
@@ -362,3 +363,24 @@ func (e *Element) Base() *Element {
 	e.r.Set(&edwards25519.B)
 	return e
 }
+
+// MarshalText implements encoding/TextMarshaler interface
+func (e *Element) MarshalText() (text []byte, err error) {
+	b := e.Encode([]byte{})
+	return []byte(base64.StdEncoding.EncodeToString(b)), nil
+}
+
+// UnmarshalText implements encoding/TextMarshaler interface
+func (e *Element) UnmarshalText(text []byte) error {
+	eb, err := base64.StdEncoding.DecodeString(string(text))
+	if err == nil {
+		return e.Decode(eb)
+	}
+	return err
+}
+
+// String implements the Stringer interface
+func (e *Element) String() string {
+	result, _ := e.MarshalText()
+	return string(result)
+}

ristretto255_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/sha512"
 	"encoding/hex"
+	"encoding/json"
 	"testing"
 
 	"github.com/gtank/ristretto255/internal/radix51"
@@ -240,3 +241,37 @@ func TestRistrettoFromUniformBytesTestVectors(t *testing.T) {
 		}
 	}
 }
+
+func TestMarshalScalar(t *testing.T) {
+	x := new(Scalar)
+	// generate an arbitrary scalar
+	xbytes := sha512.Sum512([]byte("Hello World"))
+	x.FromUniformBytes(xbytes[:])
+	text, err := json.Marshal(x)
+	if err != nil {
+		t.Fatalf("Could not marshal json: %v", err)
+	}
+	t.Logf("json: %s", text)
+	y := new(Scalar)
+	err = json.Unmarshal(text, y)
+	if err != nil || y.Equal(x) == 0 {
+		t.Fatalf("Error unmarshaling scalar from json: %s %v", text, err)
+	}
+}
+
+func TestMarshalElement(t *testing.T) {
+	x := new(Element)
+	// generate an arbitrary element
+	xbytes := sha512.Sum512([]byte("Hello World"))
+	x.FromUniformBytes(xbytes[:])
+	text, err := json.Marshal(x)
+	if err != nil {
+		t.Fatalf("Could not marshal json: %v", err)
+	}
+	t.Logf("json: %s", text)
+	y := new(Element)
+	err = json.Unmarshal(text, y)
+	if err != nil || y.Equal(x) == 0 {
+		t.Fatalf("Error unmarshaling element from json: %s %v", text, err)
+	}
+}

scalar.go

@@ -5,6 +5,7 @@
 package ristretto255
 
 import (
+	"encoding/base64"
 	"github.com/gtank/ristretto255/internal/scalar"
 )
 
@@ -82,3 +83,24 @@ func (s *Scalar) Zero() *Scalar {
 	s.s = scalar.Scalar{}
 	return s
 }
+
+// MarshalText implements encoding/TextMarshaler interface
+func (s *Scalar) MarshalText() (text []byte, err error) {
+	b := s.Encode([]byte{})
+	return []byte(base64.StdEncoding.EncodeToString(b)), nil
+}
+
+// UnmarshalText implements encoding/TextMarshaler interface
+func (s *Scalar) UnmarshalText(text []byte) error {
+	sb, err := base64.StdEncoding.DecodeString(string(text))
+	if err == nil {
+		return s.Decode(sb)
+	}
+	return err
+}
+
+// String implements the Stringer interface
+func (s *Scalar) String() string {
+	result, _ := s.MarshalText()
+	return string(result)
+}