1 files changed, 129 insertions, 0 deletions
diff --git a/whisper/envelope.go b/whisper/envelope.go
new file mode 100644
index 000000000..20e3e6d39
--- /dev/null
+++ b/whisper/envelope.go
@@ -0,0 +1,129 @@
+package whisper
+
+import (
+	"crypto/ecdsa"
+	"encoding/binary"
+	"fmt"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/crypto/ecies"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+const (
+	DefaultPow = 50 * time.Millisecond
+)
+
+type Envelope struct {
+	Expiry uint32 // Whisper protocol specifies int32, really should be int64
+	TTL    uint32 // ^^^^^^
+	Topics [][]byte
+	Data   []byte
+	Nonce  uint32
+
+	hash common.Hash
+}
+
+func (self *Envelope) Hash() common.Hash {
+	if (self.hash == common.Hash{}) {
+		enc, _ := rlp.EncodeToBytes(self)
+		self.hash = crypto.Sha3Hash(enc)
+	}
+	return self.hash
+}
+
+func NewEnvelope(ttl time.Duration, topics [][]byte, data *Message) *Envelope {
+	exp := time.Now().Add(ttl)
+	return &Envelope{
+		Expiry: uint32(exp.Unix()),
+		TTL:    uint32(ttl.Seconds()),
+		Topics: topics,
+		Data:   data.Bytes(),
+		Nonce:  0,
+	}
+}
+
+func (self *Envelope) Seal(pow time.Duration) {
+	self.proveWork(pow)
+}
+
+func (self *Envelope) Open(prv *ecdsa.PrivateKey) (msg *Message, err error) {
+	data := self.Data
+	var message Message
+	dataStart := 1
+	if data[0] > 0 {
+		if len(data) < 66 {
+			return nil, fmt.Errorf("unable to open envelope. First bit set but len(data) < 66")
+		}
+		dataStart = 66
+		message.Flags = data[0]
+		message.Signature = data[1:66]
+	}
+
+	payload := data[dataStart:]
+	if prv != nil {
+		message.Payload, err = crypto.Decrypt(prv, payload)
+		switch err {
+		case nil: // OK
+		case ecies.ErrInvalidPublicKey: // Payload isn't encrypted
+			message.Payload = payload
+			return &message, err
+		default:
+			return nil, fmt.Errorf("unable to open envelope. Decrypt failed: %v", err)
+		}
+	}
+
+	return &message, nil
+}
+
+func (self *Envelope) proveWork(dura time.Duration) {
+	var bestBit int
+	d := make([]byte, 64)
+	enc, _ := rlp.EncodeToBytes(self.withoutNonce())
+	copy(d[:32], enc)
+
+	then := time.Now().Add(dura).UnixNano()
+	for n := uint32(0); time.Now().UnixNano() < then; {
+		for i := 0; i < 1024; i++ {
+			binary.BigEndian.PutUint32(d[60:], n)
+
+			fbs := common.FirstBitSet(common.BigD(crypto.Sha3(d)))
+			if fbs > bestBit {
+				bestBit = fbs
+				self.Nonce = n
+			}
+
+			n++
+		}
+	}
+}
+
+func (self *Envelope) valid() bool {
+	d := make([]byte, 64)
+	enc, _ := rlp.EncodeToBytes(self.withoutNonce())
+	copy(d[:32], enc)
+	binary.BigEndian.PutUint32(d[60:], self.Nonce)
+	return common.FirstBitSet(common.BigD(crypto.Sha3(d))) > 0
+}
+
+func (self *Envelope) withoutNonce() interface{} {
+	return []interface{}{self.Expiry, self.TTL, self.Topics, self.Data}
+}
+
+// rlpenv is an Envelope but is not an rlp.Decoder.
+// It is used for decoding because we need to
+type rlpenv Envelope
+
+func (self *Envelope) DecodeRLP(s *rlp.Stream) error {
+	raw, err := s.Raw()
+	if err != nil {
+		return err
+	}
+	if err := rlp.DecodeBytes(raw, (*rlpenv)(self)); err != nil {
+		return err
+	}
+	self.hash = crypto.Sha3Hash(raw)
+	return nil
+}