make handshake and crypto internal packages

internal/handshake/interface.go

@@ -0,0 +1,27 @@
+package handshake
+
+import "github.com/lucas-clemente/quic-go/internal/protocol"
+
+// Sealer seals a packet
+type Sealer interface {
+	Seal(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) []byte
+	Overhead() int
+}
+
+// CryptoSetup is a crypto setup
+type CryptoSetup interface {
+	Open(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) ([]byte, protocol.EncryptionLevel, error)
+	HandleCryptoStream() error
+	// TODO: clean up this interface
+	DiversificationNonce() []byte   // only needed for cryptoSetupServer
+	SetDiversificationNonce([]byte) // only needed for cryptoSetupClient
+
+	GetSealer() (protocol.EncryptionLevel, Sealer)
+	GetSealerWithEncryptionLevel(protocol.EncryptionLevel) (Sealer, error)
+	GetSealerForCryptoStream() (protocol.EncryptionLevel, Sealer)
+}
+
+// TransportParameters are parameters sent to the peer during the handshake
+type TransportParameters struct {
+	RequestConnectionIDTruncation bool
+}