OpenSSL improve memory handling

- replace void * with BIGNUM * where applicable - fixes #1622 - replace 0 with None when using a NULL pointer as parameter - maybe needs more work in how the data is accessed - EC_POINT struct is now defined but isn't used yet
2021-02-17 13:15:34 +01:00
5 changed files with 153 additions and 113 deletions
--- a/src/pyelliptic/ecc.py
+++ b/src/pyelliptic/ecc.py
@ -82,10 +82,9 @@ class ECC(object):
            self.pubkey_y = None
            self.privkey = None
            raise Exception("Bad ECC keys ...")
-        else:
-            self.pubkey_x = pubkey_x
-            self.pubkey_y = pubkey_y
-            self.privkey = privkey
+        self.pubkey_x = pubkey_x
+        self.pubkey_y = pubkey_y
+        self.privkey = privkey

    @staticmethod
    def get_curves():
@ -211,8 +210,8 @@ class ECC(object):
            if other_key == 0:
                raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")

-            other_pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), 0)
-            other_pub_key_y = OpenSSL.BN_bin2bn(pubkey_y, len(pubkey_y), 0)
+            other_pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), None)
+            other_pub_key_y = OpenSSL.BN_bin2bn(pubkey_y, len(pubkey_y), None)

            other_group = OpenSSL.EC_KEY_get0_group(other_key)
            other_pub_key = OpenSSL.EC_POINT_new(other_group)
@ -233,7 +232,7 @@ class ECC(object):
            if own_key == 0:
                raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
            own_priv_key = OpenSSL.BN_bin2bn(
-                self.privkey, len(self.privkey), 0)
+                self.privkey, len(self.privkey), None)

            if (OpenSSL.EC_KEY_set_private_key(own_key, own_priv_key)) == 0:
                raise Exception("[OpenSSL] EC_KEY_set_private_key FAIL ...")
@ -279,16 +278,14 @@ class ECC(object):
            curve = self.curve
        elif isinstance(curve, str):
            curve = OpenSSL.get_curve(curve)
-        else:
-            curve = curve
        try:
            key = OpenSSL.EC_KEY_new_by_curve_name(curve)
            if key == 0:
                raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")
            if privkey is not None:
-                priv_key = OpenSSL.BN_bin2bn(privkey, len(privkey), 0)
-            pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), 0)
-            pub_key_y = OpenSSL.BN_bin2bn(pubkey_y, len(pubkey_y), 0)
+                priv_key = OpenSSL.BN_bin2bn(privkey, len(privkey), None)
+            pub_key_x = OpenSSL.BN_bin2bn(pubkey_x, len(pubkey_x), None)
+            pub_key_y = OpenSSL.BN_bin2bn(pubkey_y, len(pubkey_y), None)

            if privkey is not None:
                if (OpenSSL.EC_KEY_set_private_key(key, priv_key)) == 0:
@ -338,9 +335,11 @@ class ECC(object):
            if key == 0:
                raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")

-            priv_key = OpenSSL.BN_bin2bn(self.privkey, len(self.privkey), 0)
-            pub_key_x = OpenSSL.BN_bin2bn(self.pubkey_x, len(self.pubkey_x), 0)
-            pub_key_y = OpenSSL.BN_bin2bn(self.pubkey_y, len(self.pubkey_y), 0)
+            priv_key = OpenSSL.BN_bin2bn(self.privkey, len(self.privkey), None)
+            pub_key_x = OpenSSL.BN_bin2bn(self.pubkey_x, len(self.pubkey_x),
+                                          None)
+            pub_key_y = OpenSSL.BN_bin2bn(self.pubkey_y, len(self.pubkey_y),
+                                          None)

            if (OpenSSL.EC_KEY_set_private_key(key, priv_key)) == 0:
                raise Exception("[OpenSSL] EC_KEY_set_private_key FAIL ...")
@ -405,8 +404,10 @@ class ECC(object):
            if key == 0:
                raise Exception("[OpenSSL] EC_KEY_new_by_curve_name FAIL ...")

-            pub_key_x = OpenSSL.BN_bin2bn(self.pubkey_x, len(self.pubkey_x), 0)
-            pub_key_y = OpenSSL.BN_bin2bn(self.pubkey_y, len(self.pubkey_y), 0)
+            pub_key_x = OpenSSL.BN_bin2bn(self.pubkey_x, len(self.pubkey_x),
+                                          None)
+            pub_key_y = OpenSSL.BN_bin2bn(self.pubkey_y, len(self.pubkey_y),
+                                          None)
            group = OpenSSL.EC_KEY_get0_group(key)
            pub_key = OpenSSL.EC_POINT_new(group)

@ -477,9 +478,9 @@ class ECC(object):
        key = sha512(ephem.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
        key_e, key_m = key[:32], key[32:]
        pubkey = ephem.get_pubkey()
-        iv = OpenSSL.rand(OpenSSL.get_cipher(ciphername).get_blocksize())
-        ctx = Cipher(key_e, iv, 1, ciphername)
-        ciphertext = iv + pubkey + ctx.ciphering(data)
+        _iv = OpenSSL.rand(OpenSSL.get_cipher(ciphername).get_blocksize())
+        ctx = Cipher(key_e, _iv, 1, ciphername)
+        ciphertext = _iv + pubkey + ctx.ciphering(data)
        mac = hmac_sha256(key_m, ciphertext)
        return ciphertext + mac

@ -488,16 +489,21 @@ class ECC(object):
        Decrypt data with ECIES method using the local private key
        """
        blocksize = OpenSSL.get_cipher(ciphername).get_blocksize()
-        iv = data[:blocksize]
+        _iv = data[:blocksize]
        i = blocksize
-        _, pubkey_x, pubkey_y, i2 = ECC._decode_pubkey(data[i:])
-        i += i2
+        _, pubkey_x, pubkey_y, _i2 = ECC._decode_pubkey(data[i:])
+        i += _i2
        ciphertext = data[i:len(data) - 32]
        i += len(ciphertext)
        mac = data[i:]
        key = sha512(self.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
        key_e, key_m = key[:32], key[32:]
        if not equals(hmac_sha256(key_m, data[:len(data) - 32]), mac):
+            print "b1"
            raise RuntimeError("Fail to verify data")
-        ctx = Cipher(key_e, iv, 0, ciphername)
-        return ctx.ciphering(ciphertext)
+        print "b2"
+        ctx = Cipher(key_e, _iv, 0, ciphername)
+        print "c"
+        retval = ctx.ciphering(ciphertext)
+        print "d"
+        return retval
--- a/src/pyelliptic/eccblind.py
+++ b/src/pyelliptic/eccblind.py
@ -110,7 +110,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
        """
        ECC inversion
        """
-        inverse = OpenSSL.BN_mod_inverse(0, a, self.n, self.ctx)
+        inverse = OpenSSL.BN_mod_inverse(None, a, self.n, self.ctx)
        return inverse

    def ec_gen_keypair(self):
@ -120,7 +120,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
        """
        d = self.ec_get_random()
        Q = OpenSSL.EC_POINT_new(self.group)
-        OpenSSL.EC_POINT_mul(self.group, Q, d, 0, 0, 0)
+        OpenSSL.EC_POINT_mul(self.group, Q, d, None, None, None)
        return (d, Q)

    def ec_Ftor(self, F):
@ -140,7 +140,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
            x = OpenSSL.BN_new()
            y = OpenSSL.BN_new()
            OpenSSL.EC_POINT_get_affine_coordinates(
-                self.group, point, x, y, 0)
+                self.group, point, x, y, None)
            y_byte = (OpenSSL.BN_is_odd(y) & Y_BIT) | COMPRESSED_BIT
            l_ = OpenSSL.BN_num_bytes(self.n)
            try:
@ -161,7 +161,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
    def _ec_point_deserialize(self, data):
        """Make a string into an EC point"""
        y_bit, x_raw = unpack(EC, data)
-        x = OpenSSL.BN_bin2bn(x_raw, OpenSSL.BN_num_bytes(self.n), 0)
+        x = OpenSSL.BN_bin2bn(x_raw, OpenSSL.BN_num_bytes(self.n), None)
        y_bit &= Y_BIT
        retval = OpenSSL.EC_POINT_new(self.group)
        OpenSSL.EC_POINT_set_compressed_coordinates(self.group,
@ -185,7 +185,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes

    def _bn_deserialize(self, data):
        """Make a BigNum out of string"""
-        x = OpenSSL.BN_bin2bn(data, OpenSSL.BN_num_bytes(self.n), 0)
+        x = OpenSSL.BN_bin2bn(data, OpenSSL.BN_num_bytes(self.n), None)
        return x

    def _init_privkey(self, privkey):
@ -262,7 +262,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes

        # R = kG
        self.R = OpenSSL.EC_POINT_new(self.group)
-        OpenSSL.EC_POINT_mul(self.group, self.R, self.k, 0, 0, 0)
+        OpenSSL.EC_POINT_mul(self.group, self.R, self.k, None, None, None)

        return self._ec_point_serialize(self.R)

@ -287,17 +287,18 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes

            # F = b^-1 * R...
            self.binv = self.ec_invert(self.b)
-            OpenSSL.EC_POINT_mul(self.group, temp, 0, self.R, self.binv, 0)
+            OpenSSL.EC_POINT_mul(self.group, temp, None, self.R, self.binv,
+                                 None)
            OpenSSL.EC_POINT_copy(self.F, temp)

            # ... + a*b^-1 * Q...
            OpenSSL.BN_mul(abinv, self.a, self.binv, self.ctx)
-            OpenSSL.EC_POINT_mul(self.group, temp, 0, self.Q, abinv, 0)
-            OpenSSL.EC_POINT_add(self.group, self.F, self.F, temp, 0)
+            OpenSSL.EC_POINT_mul(self.group, temp, None, self.Q, abinv, None)
+            OpenSSL.EC_POINT_add(self.group, self.F, self.F, temp, None)

            # ... + c*G
-            OpenSSL.EC_POINT_mul(self.group, temp, 0, self.G, self.c, 0)
-            OpenSSL.EC_POINT_add(self.group, self.F, self.F, temp, 0)
+            OpenSSL.EC_POINT_mul(self.group, temp, None, self.G, self.c, None)
+            OpenSSL.EC_POINT_add(self.group, self.F, self.F, temp, None)

        # F = (x0, y0)
        self.r = self.ec_Ftor(self.F)
@ -356,10 +357,10 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
        lhs = OpenSSL.EC_POINT_new(self.group)
        rhs = OpenSSL.EC_POINT_new(self.group)

-        OpenSSL.EC_POINT_mul(self.group, lhs, s, 0, 0, 0)
+        OpenSSL.EC_POINT_mul(self.group, lhs, s, None, None, None)

-        OpenSSL.EC_POINT_mul(self.group, rhs, 0, self.Q, self.m, 0)
-        OpenSSL.EC_POINT_mul(self.group, rhs, 0, rhs, self.r, 0)
+        OpenSSL.EC_POINT_mul(self.group, rhs, None, self.Q, self.m, None)
+        OpenSSL.EC_POINT_mul(self.group, rhs, None, rhs, self.r, None)
        OpenSSL.EC_POINT_add(self.group, rhs, rhs, self.F, self.ctx)

        retval = OpenSSL.EC_POINT_cmp(self.group, lhs, rhs, self.ctx)
--- a/src/pyelliptic/hash.py
+++ b/src/pyelliptic/hash.py
@ -41,7 +41,13 @@ def hmac_sha256(k, m):
    d = OpenSSL.malloc(m, len(m))
    md = OpenSSL.malloc(0, 32)
    i = OpenSSL.pointer(OpenSSL.c_int(0))
-    OpenSSL.HMAC(OpenSSL.EVP_sha256(), key, len(k), d, len(m), md, i)
+    print("calculating")
+    try:
+        OpenSSL.HMAC(OpenSSL.EVP_sha256(), key, len(k), d, len(m), md, i)
+    except Exception as e:
+        print(e)
+        raise e
+    # print(i.contents)
    return md.raw


@ -53,7 +59,9 @@ def hmac_sha512(k, m):
    d = OpenSSL.malloc(m, len(m))
    md = OpenSSL.malloc(0, 64)
    i = OpenSSL.pointer(OpenSSL.c_int(0))
+    print("calculating")
    OpenSSL.HMAC(OpenSSL.EVP_sha512(), key, len(k), d, len(m), md, i)
+    print(i.contents)
    return md.raw


--- a/src/pyelliptic/openssl.py
+++ b/src/pyelliptic/openssl.py
@ -72,6 +72,29 @@ def get_version(library):
    return (version, hexversion, cflags)


+class BIGNUM(ctypes.Structure):  # pylint: disable=too-few-public-methods
+    """OpenSSL's BIGNUM struct"""
+    _fields_ = [
+        ('d', ctypes.POINTER(ctypes.c_ulong)),
+        ('top', ctypes.c_int),
+        ('dmax', ctypes.c_int),
+        ('neg', ctypes.c_int),
+        ('flags', ctypes.c_int),
+    ]
+
+
+class EC_POINT(ctypes.Structure):  # pylint: disable=too-few-public-methods
+    """OpenSSL's EC_POINT struct"""
+    _fields_ = [
+        ('meth', ctypes.c_void_p),
+        ('curve_name', ctypes.c_int),
+        ('X', ctypes.POINTER(BIGNUM)),
+        ('Y', ctypes.POINTER(BIGNUM)),
+        ('Z', ctypes.POINTER(BIGNUM)),
+        ('Z_is_one', ctypes.c_int),
+    ]
+
+
 class _OpenSSL(object):
    """
    Wrapper for OpenSSL using ctypes
@ -91,38 +114,38 @@ class _OpenSSL(object):
        self.create_string_buffer = ctypes.create_string_buffer

        self.BN_new = self._lib.BN_new
-        self.BN_new.restype = ctypes.c_void_p
+        self.BN_new.restype = ctypes.POINTER(BIGNUM)
        self.BN_new.argtypes = []

        self.BN_free = self._lib.BN_free
        self.BN_free.restype = None
-        self.BN_free.argtypes = [ctypes.c_void_p]
+        self.BN_free.argtypes = [ctypes.POINTER(BIGNUM)]

        self.BN_clear_free = self._lib.BN_clear_free
        self.BN_clear_free.restype = None
-        self.BN_clear_free.argtypes = [ctypes.c_void_p]
+        self.BN_clear_free.argtypes = [ctypes.POINTER(BIGNUM)]

        self.BN_num_bits = self._lib.BN_num_bits
        self.BN_num_bits.restype = ctypes.c_int
-        self.BN_num_bits.argtypes = [ctypes.c_void_p]
+        self.BN_num_bits.argtypes = [ctypes.POINTER(BIGNUM)]

        self.BN_bn2bin = self._lib.BN_bn2bin
        self.BN_bn2bin.restype = ctypes.c_int
-        self.BN_bn2bin.argtypes = [ctypes.c_void_p, ctypes.c_void_p]
+        self.BN_bn2bin.argtypes = [ctypes.POINTER(BIGNUM), ctypes.c_void_p]

        try:
            self.BN_bn2binpad = self._lib.BN_bn2binpad
            self.BN_bn2binpad.restype = ctypes.c_int
-            self.BN_bn2binpad.argtypes = [ctypes.c_void_p, ctypes.c_void_p,
+            self.BN_bn2binpad.argtypes = [ctypes.POINTER(BIGNUM), ctypes.c_void_p,
                                          ctypes.c_int]
        except AttributeError:
            # optional, we have a workaround
            pass

        self.BN_bin2bn = self._lib.BN_bin2bn
-        self.BN_bin2bn.restype = ctypes.c_void_p
+        self.BN_bin2bn.restype = ctypes.POINTER(BIGNUM)
        self.BN_bin2bn.argtypes = [ctypes.c_void_p, ctypes.c_int,
-                                   ctypes.c_void_p]
+                                   ctypes.POINTER(BIGNUM)]

        self.EC_KEY_free = self._lib.EC_KEY_free
        self.EC_KEY_free.restype = None
@ -156,9 +179,9 @@ class _OpenSSL(object):
            self._lib.EC_POINT_get_affine_coordinates_GFp
        self.EC_POINT_get_affine_coordinates_GFp.restype = ctypes.c_int
        self.EC_POINT_get_affine_coordinates_GFp.argtypes = [ctypes.c_void_p,
-                                                             ctypes.c_void_p,
-                                                             ctypes.c_void_p,
-                                                             ctypes.c_void_p,
+                                                             ctypes.POINTER(EC_POINT),
+                                                             ctypes.POINTER(BIGNUM),
+                                                             ctypes.POINTER(BIGNUM),
                                                             ctypes.c_void_p]

        try:
@ -170,20 +193,20 @@ class _OpenSSL(object):
                self._lib.EC_POINT_get_affine_coordinates_GF2m
        self.EC_POINT_get_affine_coordinates.restype = ctypes.c_int
        self.EC_POINT_get_affine_coordinates.argtypes = [ctypes.c_void_p,
-                                                         ctypes.c_void_p,
-                                                         ctypes.c_void_p,
-                                                         ctypes.c_void_p,
+                                                         ctypes.POINTER(EC_POINT),
+                                                         ctypes.POINTER(BIGNUM),
+                                                         ctypes.POINTER(BIGNUM),
                                                         ctypes.c_void_p]

        self.EC_KEY_set_private_key = self._lib.EC_KEY_set_private_key
        self.EC_KEY_set_private_key.restype = ctypes.c_int
        self.EC_KEY_set_private_key.argtypes = [ctypes.c_void_p,
-                                                ctypes.c_void_p]
+                                                ctypes.POINTER(BIGNUM)]

        self.EC_KEY_set_public_key = self._lib.EC_KEY_set_public_key
        self.EC_KEY_set_public_key.restype = ctypes.c_int
        self.EC_KEY_set_public_key.argtypes = [ctypes.c_void_p,
-                                               ctypes.c_void_p]
+                                               ctypes.POINTER(EC_POINT)]

        self.EC_KEY_set_group = self._lib.EC_KEY_set_group
        self.EC_KEY_set_group.restype = ctypes.c_int
@ -194,9 +217,9 @@ class _OpenSSL(object):
            self._lib.EC_POINT_set_affine_coordinates_GFp
        self.EC_POINT_set_affine_coordinates_GFp.restype = ctypes.c_int
        self.EC_POINT_set_affine_coordinates_GFp.argtypes = [ctypes.c_void_p,
-                                                             ctypes.c_void_p,
-                                                             ctypes.c_void_p,
-                                                             ctypes.c_void_p,
+                                                             ctypes.POINTER(EC_POINT),
+                                                             ctypes.POINTER(BIGNUM),
+                                                             ctypes.POINTER(BIGNUM),
                                                             ctypes.c_void_p]

        try:
@ -208,9 +231,9 @@ class _OpenSSL(object):
                self._lib.EC_POINT_set_affine_coordinates_GF2m
        self.EC_POINT_set_affine_coordinates.restype = ctypes.c_int
        self.EC_POINT_set_affine_coordinates.argtypes = [ctypes.c_void_p,
-                                                         ctypes.c_void_p,
-                                                         ctypes.c_void_p,
-                                                         ctypes.c_void_p,
+                                                         ctypes.POINTER(EC_POINT),
+                                                         ctypes.POINTER(BIGNUM),
+                                                         ctypes.POINTER(BIGNUM),
                                                         ctypes.c_void_p]

        try:
@ -219,38 +242,39 @@ class _OpenSSL(object):
        except AttributeError:
            # OpenSSL docs say only use this for backwards compatibility
            self.EC_POINT_set_compressed_coordinates = \
-                self._lib.EC_POINT_set_compressed_coordinates_GF2m
+                self._lib.EC_POINT_set_compressed_coordinates_GFp
        self.EC_POINT_set_compressed_coordinates.restype = ctypes.c_int
        self.EC_POINT_set_compressed_coordinates.argtypes = [ctypes.c_void_p,
-                                                             ctypes.c_void_p,
-                                                             ctypes.c_void_p,
+                                                             ctypes.POINTER(EC_POINT),
+                                                             ctypes.POINTER(BIGNUM),
                                                             ctypes.c_int,
                                                             ctypes.c_void_p]

        self.EC_POINT_new = self._lib.EC_POINT_new
-        self.EC_POINT_new.restype = ctypes.c_void_p
+        self.EC_POINT_new.restype = ctypes.POINTER(EC_POINT)
        self.EC_POINT_new.argtypes = [ctypes.c_void_p]

        self.EC_POINT_free = self._lib.EC_POINT_free
        self.EC_POINT_free.restype = None
-        self.EC_POINT_free.argtypes = [ctypes.c_void_p]
+        self.EC_POINT_free.argtypes = [ctypes.POINTER(EC_POINT)]

        self.BN_CTX_free = self._lib.BN_CTX_free
        self.BN_CTX_free.restype = None
        self.BN_CTX_free.argtypes = [ctypes.c_void_p]

        self.EC_POINT_mul = self._lib.EC_POINT_mul
-        self.EC_POINT_mul.restype = None
+        self.EC_POINT_mul.restype = ctypes.c_int
        self.EC_POINT_mul.argtypes = [ctypes.c_void_p,
-                                      ctypes.c_void_p,
-                                      ctypes.c_void_p,
-                                      ctypes.c_void_p,
+                                      ctypes.POINTER(EC_POINT),
+                                      ctypes.POINTER(BIGNUM),
+                                      ctypes.POINTER(EC_POINT),
+                                      ctypes.POINTER(BIGNUM),
                                      ctypes.c_void_p]

        self.EC_KEY_set_private_key = self._lib.EC_KEY_set_private_key
        self.EC_KEY_set_private_key.restype = ctypes.c_int
        self.EC_KEY_set_private_key.argtypes = [ctypes.c_void_p,
-                                                ctypes.c_void_p]
+                                                ctypes.POINTER(BIGNUM)]

        if self._hexversion >= 0x10100000 and not self._libreSSL:
            self.EC_KEY_OpenSSL = self._lib.EC_KEY_OpenSSL
@ -469,70 +493,71 @@ class _OpenSSL(object):
        self.BN_CTX_new.argtypes = []

        self.BN_dup = self._lib.BN_dup
-        self.BN_dup.restype = ctypes.c_void_p
-        self.BN_dup.argtypes = [ctypes.c_void_p]
+        self.BN_dup.restype = ctypes.POINTER(BIGNUM)
+        self.BN_dup.argtypes = [ctypes.POINTER(BIGNUM)]

        self.BN_rand = self._lib.BN_rand
        self.BN_rand.restype = ctypes.c_int
-        self.BN_rand.argtypes = [ctypes.c_void_p,
+        self.BN_rand.argtypes = [ctypes.POINTER(BIGNUM),
+                                 ctypes.c_int,
                                 ctypes.c_int,
                                 ctypes.c_int]

        self.BN_set_word = self._lib.BN_set_word
        self.BN_set_word.restype = ctypes.c_int
-        self.BN_set_word.argtypes = [ctypes.c_void_p,
+        self.BN_set_word.argtypes = [ctypes.POINTER(BIGNUM),
                                     ctypes.c_ulong]

        self.BN_mul = self._lib.BN_mul
        self.BN_mul.restype = ctypes.c_int
-        self.BN_mul.argtypes = [ctypes.c_void_p,
-                                ctypes.c_void_p,
-                                ctypes.c_void_p,
+        self.BN_mul.argtypes = [ctypes.POINTER(BIGNUM),
+                                ctypes.POINTER(BIGNUM),
+                                ctypes.POINTER(BIGNUM),
                                ctypes.c_void_p]

        self.BN_mod_add = self._lib.BN_mod_add
        self.BN_mod_add.restype = ctypes.c_int
-        self.BN_mod_add.argtypes = [ctypes.c_void_p,
-                                    ctypes.c_void_p,
-                                    ctypes.c_void_p,
-                                    ctypes.c_void_p,
+        self.BN_mod_add.argtypes = [ctypes.POINTER(BIGNUM),
+                                    ctypes.POINTER(BIGNUM),
+                                    ctypes.POINTER(BIGNUM),
+                                    ctypes.POINTER(BIGNUM),
                                    ctypes.c_void_p]

        self.BN_mod_inverse = self._lib.BN_mod_inverse
-        self.BN_mod_inverse.restype = ctypes.c_void_p
-        self.BN_mod_inverse.argtypes = [ctypes.c_void_p,
-                                        ctypes.c_void_p,
-                                        ctypes.c_void_p,
+        self.BN_mod_inverse.restype = ctypes.POINTER(BIGNUM)
+        self.BN_mod_inverse.argtypes = [ctypes.POINTER(BIGNUM),
+                                        ctypes.POINTER(BIGNUM),
+                                        ctypes.POINTER(BIGNUM),
                                        ctypes.c_void_p]

        self.BN_mod_mul = self._lib.BN_mod_mul
        self.BN_mod_mul.restype = ctypes.c_int
-        self.BN_mod_mul.argtypes = [ctypes.c_void_p,
-                                    ctypes.c_void_p,
-                                    ctypes.c_void_p,
-                                    ctypes.c_void_p,
+        self.BN_mod_mul.argtypes = [ctypes.POINTER(BIGNUM),
+                                    ctypes.POINTER(BIGNUM),
+                                    ctypes.POINTER(BIGNUM),
+                                    ctypes.POINTER(BIGNUM),
                                    ctypes.c_void_p]

        self.BN_lshift = self._lib.BN_lshift
        self.BN_lshift.restype = ctypes.c_int
-        self.BN_lshift.argtypes = [ctypes.c_void_p,
-                                   ctypes.c_void_p,
+        self.BN_lshift.argtypes = [ctypes.POINTER(BIGNUM),
+                                   ctypes.POINTER(BIGNUM),
                                   ctypes.c_int]

        self.BN_sub_word = self._lib.BN_sub_word
        self.BN_sub_word.restype = ctypes.c_int
-        self.BN_sub_word.argtypes = [ctypes.c_void_p,
+        self.BN_sub_word.argtypes = [ctypes.POINTER(BIGNUM),
                                     ctypes.c_ulong]

        self.BN_cmp = self._lib.BN_cmp
        self.BN_cmp.restype = ctypes.c_int
-        self.BN_cmp.argtypes = [ctypes.c_void_p,
-                                ctypes.c_void_p]
+        self.BN_cmp.argtypes = [ctypes.POINTER(BIGNUM),
+                                ctypes.POINTER(BIGNUM)]

        try:
            self.BN_is_odd = self._lib.BN_is_odd
            self.BN_is_odd.restype = ctypes.c_int
-            self.BN_is_odd.argtypes = [ctypes.c_void_p]
+            self.BN_is_odd.argtypes = [ctypes.POINTER(BIGNUM)]
        except AttributeError:
            # OpenSSL 1.1.0 implements this as a function, but earlier
            # versions as macro, so we need to workaround
@ -540,7 +565,7 @@ class _OpenSSL(object):

        self.BN_bn2dec = self._lib.BN_bn2dec
        self.BN_bn2dec.restype = ctypes.c_char_p
-        self.BN_bn2dec.argtypes = [ctypes.c_void_p]
+        self.BN_bn2dec.argtypes = [ctypes.POINTER(BIGNUM)]

        self.EC_GROUP_new_by_curve_name = self._lib.EC_GROUP_new_by_curve_name
        self.EC_GROUP_new_by_curve_name.restype = ctypes.c_void_p
@ -549,43 +574,43 @@ class _OpenSSL(object):
        self.EC_GROUP_get_order = self._lib.EC_GROUP_get_order
        self.EC_GROUP_get_order.restype = ctypes.c_int
        self.EC_GROUP_get_order.argtypes = [ctypes.c_void_p,
-                                            ctypes.c_void_p,
+                                            ctypes.POINTER(BIGNUM),
                                            ctypes.c_void_p]

        self.EC_GROUP_get_cofactor = self._lib.EC_GROUP_get_cofactor
        self.EC_GROUP_get_cofactor.restype = ctypes.c_int
        self.EC_GROUP_get_cofactor.argtypes = [ctypes.c_void_p,
-                                               ctypes.c_void_p,
+                                               ctypes.POINTER(BIGNUM),
                                               ctypes.c_void_p]

        self.EC_GROUP_get0_generator = self._lib.EC_GROUP_get0_generator
-        self.EC_GROUP_get0_generator.restype = ctypes.c_void_p
+        self.EC_GROUP_get0_generator.restype = ctypes.POINTER(EC_POINT)
        self.EC_GROUP_get0_generator.argtypes = [ctypes.c_void_p]

        self.EC_POINT_copy = self._lib.EC_POINT_copy
        self.EC_POINT_copy.restype = ctypes.c_int
-        self.EC_POINT_copy.argtypes = [ctypes.c_void_p,
-                                       ctypes.c_void_p]
+        self.EC_POINT_copy.argtypes = [ctypes.POINTER(EC_POINT),
+                                       ctypes.POINTER(EC_POINT)]

        self.EC_POINT_add = self._lib.EC_POINT_add
        self.EC_POINT_add.restype = ctypes.c_int
        self.EC_POINT_add.argtypes = [ctypes.c_void_p,
-                                      ctypes.c_void_p,
-                                      ctypes.c_void_p,
-                                      ctypes.c_void_p,
+                                      ctypes.POINTER(EC_POINT),
+                                      ctypes.POINTER(EC_POINT),
+                                      ctypes.POINTER(EC_POINT),
                                      ctypes.c_void_p]

        self.EC_POINT_cmp = self._lib.EC_POINT_cmp
        self.EC_POINT_cmp.restype = ctypes.c_int
        self.EC_POINT_cmp.argtypes = [ctypes.c_void_p,
-                                      ctypes.c_void_p,
-                                      ctypes.c_void_p,
+                                      ctypes.POINTER(EC_POINT),
+                                      ctypes.POINTER(EC_POINT),
                                      ctypes.c_void_p]

        self.EC_POINT_set_to_infinity = self._lib.EC_POINT_set_to_infinity
        self.EC_POINT_set_to_infinity.restype = ctypes.c_int
        self.EC_POINT_set_to_infinity.argtypes = [ctypes.c_void_p,
-                                                  ctypes.c_void_p]
+                                                  ctypes.POINTER(EC_POINT)]

        self._set_ciphers()
        self._set_curves()
@ -722,9 +747,9 @@ class _OpenSSL(object):
        if data != 0:
            if sys.version_info.major == 3 and isinstance(data, type('')):
                data = data.encode()
-            buffer_ = self.create_string_buffer(data, size)
+            buffer_ = self.create_string_buffer(data, size + 1)
        else:
-            buffer_ = self.create_string_buffer(size)
+            buffer_ = self.create_string_buffer(size + 1)
        return buffer_


--- a/src/tests/test_blindsig.py
+++ b/src/tests/test_blindsig.py
@ -57,7 +57,7 @@ class TestBlindSig(unittest.TestCase):
            x = OpenSSL.BN_new()
            y = OpenSSL.BN_new()
            OpenSSL.EC_POINT_get_affine_coordinates(
-                obj.group, obj.Q, x, y, 0)
+                obj.group, obj.Q, x, y, None)
            self.assertEqual(OpenSSL.BN_is_odd(y),
                             OpenSSL.BN_is_odd_compatible(y))

@ -84,7 +84,7 @@ class TestBlindSig(unittest.TestCase):
                self.assertEqual(OpenSSL.BN_cmp(y0, y1), 0)
                self.assertEqual(OpenSSL.BN_cmp(x0, x1), 0)
                self.assertEqual(OpenSSL.EC_POINT_cmp(obj.group, randompoint,
-                                                      secondpoint, 0), 0)
+                                                      secondpoint, None), 0)
            finally:
                OpenSSL.BN_free(x0)
                OpenSSL.BN_free(x1)