Make crypt testable

mtproto/wrappers/crypt.go

@@ -25,14 +25,17 @@ var emptyIP = [4]byte{0x00, 0x00, 0x00, 0x00}
 func NewMiddleProxyCipherRWC(conn wrappers.ReadWriteCloserWithAddr, req *rpc.RPCNonceRequest,
 	resp *rpc.RPCNonceResponse, client *net.TCPAddr, secret []byte) wrappers.ReadWriteCloserWithAddr {
 	remote := conn.Addr()
-	encryptor, _ := newCBCCipher(CipherPurposeClient, req, resp, client, remote, secret)
-	_, decryptor := newCBCCipher(CipherPurposeServer, req, resp, client, remote, secret)
+	encKey, encIV := makeKeys(CipherPurposeClient, req, resp, client, remote, secret)
+	decKey, decIV := makeKeys(CipherPurposeServer, req, resp, client, remote, secret)
 
-	return wrappers.NewBlockCipherRWC(conn, encryptor, decryptor)
+	enc, _ := makeEncrypterDecrypter(encKey, encIV)
+	_, dec := makeEncrypterDecrypter(decKey, decIV)
+
+	return wrappers.NewBlockCipherRWC(conn, enc, dec)
 }
 
-func newCBCCipher(purpose CipherPurpose, req *rpc.RPCNonceRequest, resp *rpc.RPCNonceResponse,
-	client *net.TCPAddr, remote *net.TCPAddr, secret []byte) (cipher.BlockMode, cipher.BlockMode) {
+func makeKeys(purpose CipherPurpose, req *rpc.RPCNonceRequest, resp *rpc.RPCNonceResponse,
+	client *net.TCPAddr, remote *net.TCPAddr, secret []byte) ([]byte, []byte) {
 	message := bytes.Buffer{}
 	message.Write(resp.Nonce[:])
 	message.Write(req.Nonce[:])
@@ -71,22 +74,23 @@ func newCBCCipher(purpose CipherPurpose, req *rpc.RPCNonceRequest, resp *rpc.RPC
 	}
 	message.Write(req.Nonce[:])
 
-	return makeCipher(message.Bytes())
+	data := message.Bytes()
+	md5sum := md5.Sum(data[1:])
+	sha1sum := sha1.Sum(data)
+
+	key := append(md5sum[:12], sha1sum[:]...)
+	iv := md5.Sum(data[2:])
+
+	return key, iv[:]
 }
 
-func makeCipher(message []byte) (cipher.BlockMode, cipher.BlockMode) {
-	md5sum := md5.Sum(message[1:])
-	sha1sum := sha1.Sum(message)
-
-	key := append(md5sum[12:], sha1sum[:]...)
-	iv := md5.Sum(message[2:])
-
+func makeEncrypterDecrypter(key, iv []byte) (cipher.BlockMode, cipher.BlockMode) {
 	block, err := aes.NewCipher(key)
 	if err != nil {
-		panic("Cannot create cipher from the given key")
+		panic(err)
 	}
 
-	return cipher.NewCBCEncrypter(block, iv[:]), cipher.NewCBCDecrypter(block, iv[:])
+	return cipher.NewCBCEncrypter(block, iv), cipher.NewCBCDecrypter(block, iv)
 }
 
 func reverseBytes(data []byte) []byte {

mtproto/wrappers/crypt_test.go

@@ -0,0 +1,45 @@
+package wrappers
+
+import (
+	"encoding/binary"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/9seconds/mtg/mtproto/rpc"
+)
+
+var proxySecret = []byte{196, 249, 250, 202, 150, 120, 230, 187, 72, 173,
+	108, 126, 44, 229, 192, 210, 68, 48, 100, 93, 85, 74, 221, 235, 85, 65,
+	158, 3, 77, 166, 39, 33, 208, 70, 234, 171, 110, 82, 171, 20, 169, 90, 68,
+	62, 207, 179, 70, 62, 121, 160, 90, 102, 97, 42, 223, 156, 174, 218, 139,
+	233, 168, 13, 166, 152, 111, 176, 166, 255, 56, 122, 248, 77, 136, 239,
+	58, 100, 19, 113, 62, 92, 51, 119, 246, 225, 163, 212, 125, 153, 245, 224,
+	197, 110, 236, 232, 240, 92, 84, 196, 144, 176, 121, 227, 27, 239, 130,
+	255, 14, 232, 242, 176, 163, 39, 86, 210, 73, 197, 242, 18, 105, 129, 108,
+	183, 6, 27, 38, 93, 178, 18}
+
+func TestMakeKeys(t *testing.T) {
+	req, err := rpc.NewRPCNonceRequest(proxySecret)
+	assert.Nil(t, err)
+
+	copy(req.Nonce[:], []byte{24, 49, 53, 111, 198, 10, 235, 180, 230, 112, 92, 78, 1, 201, 106, 105})
+	binary.LittleEndian.PutUint32(req.CryptoTS[:], 1528396015)
+
+	resp := &rpc.RPCNonceResponse{}
+	copy(resp.Nonce[:], []byte{247, 40, 210, 56, 65, 12, 101, 170, 216, 155, 14, 253, 250, 238, 219, 226})
+
+	cltAddr := &net.TCPAddr{
+		IP:   net.ParseIP("80.211.29.34"),
+		Port: 54208,
+	}
+	srvAddr := &net.TCPAddr{
+		IP:   net.ParseIP("149.154.162.38"),
+		Port: 80,
+	}
+
+	key, iv := makeKeys(CipherPurposeClient, req, resp, cltAddr, srvAddr, proxySecret)
+	assert.Equal(t, key, []byte{165, 158, 127, 49, 41, 232, 187, 69, 38, 29, 163, 226, 183, 146, 28, 67, 225, 224, 134, 191, 207, 152, 255, 166, 152, 66, 169, 196, 54, 135, 50, 188})
+	assert.Equal(t, iv, []byte{33, 110, 125, 221, 183, 121, 160, 116, 130, 180, 156, 249, 52, 111, 37, 178})
+}