make handshake and crypto internal packages

internal/crypto/chacha20poly1305_aead.go

@@ -0,0 +1,61 @@
+// +build ignore
+
+package crypto
+
+import (
+	"crypto/cipher"
+	"encoding/binary"
+	"errors"
+
+	"github.com/aead/chacha20"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+)
+
+type aeadChacha20Poly1305 struct {
+	otherIV   []byte
+	myIV      []byte
+	encrypter cipher.AEAD
+	decrypter cipher.AEAD
+}
+
+// NewAEADChacha20Poly1305 creates a AEAD using chacha20poly1305
+func NewAEADChacha20Poly1305(otherKey []byte, myKey []byte, otherIV []byte, myIV []byte) (AEAD, error) {
+	if len(myKey) != 32 || len(otherKey) != 32 || len(myIV) != 4 || len(otherIV) != 4 {
+		return nil, errors.New("chacha20poly1305: expected 32-byte keys and 4-byte IVs")
+	}
+	// copy because ChaCha20Poly1305 expects array pointers
+	var MyKey, OtherKey [32]byte
+	copy(MyKey[:], myKey)
+	copy(OtherKey[:], otherKey)
+
+	encrypter, err := chacha20.NewChaCha20Poly1305WithTagSize(&MyKey, 12)
+	if err != nil {
+		return nil, err
+	}
+	decrypter, err := chacha20.NewChaCha20Poly1305WithTagSize(&OtherKey, 12)
+	if err != nil {
+		return nil, err
+	}
+	return &aeadChacha20Poly1305{
+		otherIV:   otherIV,
+		myIV:      myIV,
+		encrypter: encrypter,
+		decrypter: decrypter,
+	}, nil
+}
+
+func (aead *aeadChacha20Poly1305) Open(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) ([]byte, error) {
+	return aead.decrypter.Open(dst, aead.makeNonce(aead.otherIV, packetNumber), src, associatedData)
+}
+
+func (aead *aeadChacha20Poly1305) Seal(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) []byte {
+	return aead.encrypter.Seal(dst, aead.makeNonce(aead.myIV, packetNumber), src, associatedData)
+}
+
+func (aead *aeadChacha20Poly1305) makeNonce(iv []byte, packetNumber protocol.PacketNumber) []byte {
+	res := make([]byte, 12)
+	copy(res[0:4], iv)
+	binary.LittleEndian.PutUint64(res[4:12], uint64(packetNumber))
+	return res
+}