Added encryption for messages better API for sealing messages

whisper/message.go

@@ -1,5 +1,11 @@
 package whisper
 
+import (
+	"time"
+
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
 type Message struct {
 	Flags     byte
 	Signature []byte
@@ -10,6 +16,49 @@ func NewMessage(payload []byte) *Message {
 	return &Message{Flags: 0, Payload: payload}
 }
 
+func (self *Message) hash() []byte {
+	return crypto.Sha3(append([]byte{self.Flags}, self.Payload...))
+}
+
+func (self *Message) sign(key []byte) (err error) {
+	self.Flags = 1
+	self.Signature, err = crypto.Sign(self.hash(), key)
+	return
+}
+
+func (self *Message) Encrypt(from, to []byte) (err error) {
+	err = self.sign(from)
+	if err != nil {
+		return err
+	}
+
+	self.Payload, err = crypto.Encrypt(to, self.Payload)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (self *Message) Bytes() []byte {
 	return append([]byte{self.Flags}, append(self.Signature, self.Payload...)...)
 }
+
+type Opts struct {
+	From, To []byte // private(sender), public(receiver) key
+	Ttl      time.Duration
+	Topics   [][]byte
+}
+
+func (self *Message) Seal(pow time.Duration, opts Opts) (*Envelope, error) {
+	if len(opts.To) > 0 && len(opts.From) > 0 {
+		if err := self.Encrypt(opts.From, opts.To); err != nil {
+			return nil, err
+		}
+	}
+
+	envelope := NewEnvelope(DefaultTtl, opts.Topics, self)
+	envelope.Seal(pow)
+
+	return envelope, nil
+}