more progress:

* add tunnel crypto

* add base boilter plate for tunnel message processing

lib/tunnel/message.go

@@ -0,0 +1,20 @@
+package tunnel
+
+import (
+  "github.com/bounce-chat/go-i2p/lib/crypto"
+  "encoding/binary"
+)
+
+type TunnelID uint32
+
+// data sent down a tunnel
+type TunnelMessage crypto.TunnelData
+
+func (tm TunnelMessage) ID() (tid TunnelID) {
+  tid = TunnelID(binary.BigEndian.Uint32(tm[:4]))
+  return
+}
+
+func (tm TunnelMessage) IV() crypto.TunnelIV {
+  return tm[4:20]
+}