Support obfuscated2

mtglib/internal/obfuscated2/client_handshake.go

@@ -0,0 +1,37 @@
+package obfuscated2
+
+import (
+	"crypto/cipher"
+	"crypto/subtle"
+	"encoding/hex"
+	"fmt"
+)
+
+// Connection Type secure. We support only fake tls.
+var clientHandshakeMagic = []byte{0xdd, 0xdd, 0xdd, 0xdd}
+
+func ClientHandshake(secret []byte, handshakeFrame *HandhakeFrame) (int16, cipher.Stream, cipher.Stream, error) {
+	decHasher := acquireSha256Hasher()
+	defer releaseSha256Hasher(decHasher)
+
+	decHasher.Write(handshakeFrame.key()) // nolint: errcheck
+	decHasher.Write(secret)               // nolint: errcheck
+	decryptor := makeAesCtr(decHasher.Sum(nil), handshakeFrame.iv())
+
+	encHasher := acquireSha256Hasher()
+	defer releaseSha256Hasher(encHasher)
+
+	invertedFrame := handshakeFrame.invert()
+	encHasher.Write(invertedFrame.key()) // nolint: errcheck
+	encHasher.Write(secret)               // nolint: errcheck
+	encryptor := makeAesCtr(encHasher.Sum(nil), invertedFrame.iv())
+
+	decryptedFrame := HandhakeFrame{}
+	decryptor.XORKeyStream(decryptedFrame.data[:], handshakeFrame.data[:])
+
+	if magic := decryptedFrame.magic(); subtle.ConstantTimeCompare(clientHandshakeMagic, magic) != 1 {
+		return 0, nil, nil, fmt.Errorf("unsupported connection type: %s", hex.EncodeToString(magic))
+	}
+
+	return decryptedFrame.dc(), encryptor, decryptor, nil
+}