Splited encoding per object type, added public methods for serialization

bson/encoding_cypher.go

@@ -0,0 +1,62 @@
+// Package bson provides functions for serialization and deserialization between
+// paillier objects and BSON
+package bson
+
+import (
+	"errors"
+	"fmt"
+	"math/big"
+
+	"github.com/keep-network/paillier"
+	"gopkg.in/mgo.v2/bson"
+)
+
+type Cypher paillier.Cypher
+
+// Serializes Cypher to BSON
+func SerializeCypher(cypher *paillier.Cypher) ([]byte, error) {
+	return bson.Marshal(toSerializableCypher(cypher))
+}
+
+// Deserializes BSON to Cypher
+func DeserializeCypher(data []byte) (*paillier.Cypher, error) {
+	serializable := new(Cypher)
+	if err := bson.Unmarshal(data, serializable); err != nil {
+		return nil, err
+	}
+
+	return toOriginalCypher(serializable), nil
+}
+
+// Changes original Cypher to serializable Cypher
+func toSerializableCypher(cypher *paillier.Cypher) *Cypher {
+	serializable := Cypher(*cypher)
+	return &serializable
+}
+
+// Changes serializable Cypher to original Cypher
+func toOriginalCypher(serializable *Cypher) *paillier.Cypher {
+	original := paillier.Cypher(*serializable)
+	return &original
+}
+
+type dbCypher struct {
+	C string
+}
+
+func (cypher *Cypher) GetBSON() (interface{}, error) {
+	return &dbCypher{fmt.Sprintf("%x", cypher.C)}, nil
+}
+
+func (cypher *Cypher) SetBSON(raw bson.Raw) error {
+	c := dbCypher{}
+	if err := raw.Unmarshal(&c); err != nil {
+		return err
+	}
+	var ok bool
+	cypher.C, ok = new(big.Int).SetString(c.C, 16)
+	if !ok {
+		return errors.New("big int not in hexadecimal format")
+	}
+	return nil
+}