make handshake and crypto internal packages

internal/handshake/server_config.go

@@ -0,0 +1,65 @@
+package handshake
+
+import (
+	"bytes"
+	"crypto/rand"
+
+	"github.com/lucas-clemente/quic-go/internal/crypto"
+)
+
+// ServerConfig is a server config
+type ServerConfig struct {
+	kex       crypto.KeyExchange
+	certChain crypto.CertChain
+	ID        []byte
+	obit      []byte
+}
+
+// NewServerConfig creates a new server config
+func NewServerConfig(kex crypto.KeyExchange, certChain crypto.CertChain) (*ServerConfig, error) {
+	id := make([]byte, 16)
+	_, err := rand.Read(id)
+	if err != nil {
+		return nil, err
+	}
+
+	obit := make([]byte, 8)
+	if _, err = rand.Read(obit); err != nil {
+		return nil, err
+	}
+
+	return &ServerConfig{
+		kex:       kex,
+		certChain: certChain,
+		ID:        id,
+		obit:      obit,
+	}, nil
+}
+
+// Get the server config binary representation
+func (s *ServerConfig) Get() []byte {
+	var serverConfig bytes.Buffer
+	msg := HandshakeMessage{
+		Tag: TagSCFG,
+		Data: map[Tag][]byte{
+			TagSCID: s.ID,
+			TagKEXS: []byte("C255"),
+			TagAEAD: []byte("AESG"),
+			TagPUBS: append([]byte{0x20, 0x00, 0x00}, s.kex.PublicKey()...),
+			TagOBIT: s.obit,
+			TagEXPY: {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+		},
+	}
+	msg.Write(&serverConfig)
+	return serverConfig.Bytes()
+}
+
+// Sign the server config and CHLO with the server's keyData
+func (s *ServerConfig) Sign(sni string, chlo []byte) ([]byte, error) {
+	return s.certChain.SignServerProof(sni, chlo, s.Get())
+}
+
+// GetCertsCompressed returns the certificate data
+func (s *ServerConfig) GetCertsCompressed(sni string, commonSetHashes, compressedHashes []byte) ([]byte, error) {
+	return s.certChain.GetCertsCompressed(sni, commonSetHashes, compressedHashes)
+}