diff --git a/pybtc/_secp256k1/module_secp256k1.c b/pybtc/_secp256k1/module_secp256k1.c
index 98451bf..a579349 100644
--- a/pybtc/_secp256k1/module_secp256k1.c
+++ b/pybtc/_secp256k1/module_secp256k1.c
@@ -14,6 +14,94 @@ secp256k1_context *secp256k1_precomp_context_verify;
 static int context_exist = 0;
 
 
+
+
+
+
+
+static PyObject *secp256k1_secp256k1_ec_pubkey_tweak_add(PyObject *self, PyObject *args) {
+    Py_buffer pubkey;
+    Py_buffer tweak;
+    int flag;
+    if (!PyArg_ParseTuple(args,"y*y*i", &pubkey, &tweak, &flag)) { return NULL; }
+    secp256k1_pubkey data;
+    int t = secp256k1_ec_pubkey_parse(secp256k1_precomp_context_sign, &data, pubkey.buf, pubkey.len);
+    if (t==0) { return Py_BuildValue("b", -1); }
+
+    t = secp256k1_ec_pubkey_tweak_add(secp256k1_context_no_precomp, &data, tweak.buf);
+    if (t==0) { return Py_BuildValue("b", -2); }
+
+    size_t outl = 33;
+    if (flag == 1) {
+      outl = 33;
+      flag = SECP256K1_EC_COMPRESSED;
+    } else {
+      outl = 65;
+      flag = SECP256K1_EC_UNCOMPRESSED;
+    }
+    unsigned char pubkeyo[outl];
+    t = secp256k1_ec_pubkey_serialize(secp256k1_context_no_precomp, pubkeyo, &outl, &data, flag);
+    if (t != 1) { return Py_BuildValue("b", 0); }
+    return Py_BuildValue("y#", pubkeyo, outl);
+    return Py_BuildValue("b", 0);
+}
+
+
+
+
+static PyObject *secp256k1_secp256k1_ecdsa_add_points(PyObject *self, PyObject *args) {
+    Py_buffer a;
+    Py_buffer b;
+    int flag;
+    if (!PyArg_ParseTuple(args,"y*y*i", &a, &b, &flag)) { return NULL; }
+    secp256k1_pubkey data[2];
+    int t = secp256k1_ec_pubkey_parse(secp256k1_context_no_precomp, data, a.buf, a.len);
+    if (t==0) { return Py_BuildValue("b", -1); }
+
+    t = secp256k1_ec_pubkey_parse(secp256k1_context_no_precomp, data + 1, b.buf, b.len);
+    if (t==0) { return Py_BuildValue("b", -1); }
+    secp256k1_pubkey out;
+    const secp256k1_pubkey* d[2];
+    d[0] = &data[0];
+    d[1] = &data[1];
+
+    t = secp256k1_ec_pubkey_combine(secp256k1_precomp_context_sign, &out,
+                                    d, 2);
+
+    size_t outl;
+    if (flag == 1) {
+      outl = 33;
+      flag = SECP256K1_EC_COMPRESSED;
+    } else {
+      outl = 65;
+      flag = SECP256K1_EC_UNCOMPRESSED;
+    }
+    unsigned char pubkeyo[outl];
+    t = secp256k1_ec_pubkey_serialize(secp256k1_context_no_precomp, pubkeyo, &outl, &out, flag);
+    if (t != 1) { return Py_BuildValue("b", 0); }
+    return Py_BuildValue("y#", pubkeyo, outl);
+    return Py_BuildValue("b", 0);
+}
+
+static PyObject *secp256k1_secp256k1_ecdsa_signature_serialize_der(PyObject *self, PyObject *args) {
+    Py_buffer sig;
+    if (!PyArg_ParseTuple(args,"y*", &sig)) { return NULL; }
+    secp256k1_ecdsa_signature signature;
+    int t = secp256k1_ecdsa_signature_parse_compact(secp256k1_context_no_precomp,
+                                                              &signature,
+                                                              sig.buf);
+    if (t==0) { return Py_BuildValue("b", 0); }
+    unsigned char outputSer[72];
+    size_t outputLen = 72;
+    t = secp256k1_ecdsa_signature_serialize_der(secp256k1_context_no_precomp,
+                                            outputSer,
+                                            &outputLen,
+                                            &signature);
+    if (t==0) { return Py_BuildValue("b", 0); }
+    return Py_BuildValue("y#", &outputSer, outputLen);
+
+}
+
 static PyObject *secp256k1_secp256k1_nonce_rfc6979(PyObject *self, PyObject *args) {
   unsigned char nonce[32];
   Py_buffer msg32;
@@ -25,8 +113,6 @@ static PyObject *secp256k1_secp256k1_nonce_rfc6979(PyObject *self, PyObject *arg
   return Py_BuildValue("y#", &nonce, 32);
 }
 
-
-
 static PyObject *secp256k1_secp256k1_ecdsa_recover(PyObject *self, PyObject *args) {
     Py_buffer message;
     Py_buffer sig;
@@ -77,7 +163,6 @@ static PyObject *secp256k1_secp256k1_ecdsa_recover(PyObject *self, PyObject *arg
     return Py_BuildValue("y#", pubkeyo, outl);
 }
 
-
 static PyObject *secp256k1_secp256k1_ecdsa_verify(PyObject *self, PyObject *args) {
     Py_buffer message;
     Py_buffer pub;
@@ -106,8 +191,6 @@ static PyObject *secp256k1_secp256k1_ecdsa_verify(PyObject *self, PyObject *args
     return Py_BuildValue("b", 1);
 }
 
-
-
 static PyObject *secp256k1_secp256k1_context_create(PyObject *self, PyObject *args) {
   if (context_exist == 0 ) {
       secp256k1_context *s = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
@@ -199,6 +282,9 @@ static PyMethodDef module_methods[] = {
     {"secp256k1_ecdsa_verify", secp256k1_secp256k1_ecdsa_verify, METH_VARARGS, "Verify signature"},
     {"secp256k1_ecdsa_recover", secp256k1_secp256k1_ecdsa_recover, METH_VARARGS, "Recover public key from signature"},
     {"secp256k1_nonce_rfc6979", secp256k1_secp256k1_nonce_rfc6979, METH_VARARGS, "Create rfc6979 nonce"},
+    {"secp256k1_ecdsa_signature_serialize_der", secp256k1_secp256k1_ecdsa_signature_serialize_der, METH_VARARGS, "Serialize to DER"},
+    {"secp256k1_ecdsa_add_points", secp256k1_secp256k1_ecdsa_add_points, METH_VARARGS, "2 points addition"},
+    {"secp256k1_ec_pubkey_tweak_add", secp256k1_secp256k1_ec_pubkey_tweak_add, METH_VARARGS, "tweak addition "},
     {NULL, NULL, 0, NULL}
 };
 
diff --git a/pybtc/crypto.py b/pybtc/crypto.py
index 8fd2c28..e526bfc 100644
--- a/pybtc/crypto.py
+++ b/pybtc/crypto.py
@@ -40,6 +40,16 @@ def __secp256k1_ecdsa_recover__(signature, message, rec_id, compressed = True):
 def __secp256k1_nonce_rfc6979__(msg32, key32, counter):
     return _secp256k1.secp256k1_nonce_rfc6979(msg32, key32, counter)
 
+def __secp256k1_ecdsa_signature_serialize_der__(raw_sig):
+    return _secp256k1.secp256k1_ecdsa_signature_serialize_der(raw_sig)
+
+def __secp256k1_ecdsa_add_points__(a, b, flag):
+    return _secp256k1.secp256k1_ecdsa_add_points(a, b, int(flag))
+
+def __secp256k1_ec_pubkey_tweak_add__(pubkey, tweak, compressed = True):
+    return _secp256k1.secp256k1_ec_pubkey_tweak_add(pubkey, tweak, int(compressed))
+
+
 
 if (__secp256k1_context_create__()):
     __secp256k1_context_randomize__()
\ No newline at end of file
diff --git a/pybtc/functions/bip32.py b/pybtc/functions/bip32.py
index 624902a..7494d7f 100644
--- a/pybtc/functions/bip32.py
+++ b/pybtc/functions/bip32.py
@@ -1,12 +1,11 @@
 from struct import pack
-from secp256k1 import ffi, lib
 from pybtc.functions.key import private_to_public_key, private_key_to_wif
 from pybtc.functions.hash import hmac_sha512, double_sha256, hash160
 from pybtc.functions.encode import (encode_base58,
                                     decode_base58_with_checksum,
                                     encode_base58_with_checksum)
 from pybtc.constants import *
-
+from pybtc.crypto import __secp256k1_ec_pubkey_tweak_add__
 
 def create_master_xprivate_key(seed, testnet=False, base58=True, hex=False):
     """
@@ -145,17 +144,10 @@ def derive_child_xpublic_key(xpublic_key, i):
     s = hmac_sha512(c, k + pack(">L", i))
     if int.from_bytes(s[:32], byteorder='big') >= ECDSA_SEC256K1_ORDER:
         return None
-    pubkey_ptr = ffi.new('secp256k1_pubkey *')
-    if not lib.secp256k1_ec_pubkey_parse(ECDSA_CONTEXT_VERIFY, pubkey_ptr, k, len(k)):
-        raise RuntimeError("secp256k1 parse public key operation failed")
-    if not lib.secp256k1_ec_pubkey_tweak_add(ECDSA_CONTEXT_ALL, pubkey_ptr, s[:32]):
-        raise RuntimeError("secp256k1 parse tweak addition operation failed")
-    pubkey = ffi.new('char [%d]' % 33)
-    outlen = ffi.new('size_t *', 33)
-    if not lib.secp256k1_ec_pubkey_serialize(ECDSA_CONTEXT_VERIFY, pubkey, outlen, pubkey_ptr, EC_COMPRESSED):
-        raise RuntimeError("secp256k1 serialize public key operation failed")
-    pk = bytes(ffi.buffer(pubkey, 33))
-    print(len(pk))
+
+    pk = __secp256k1_ec_pubkey_tweak_add__(k, s[:32])
+    if isinstance(pk, int):
+        raise RuntimeError("pubkey_tweak_add error %s" %pk)
     return b"".join([xpublic_key[:4],
                      bytes([depth]),
                      fingerprint,