Blind signature updates

- added serializing and deserializing
- added a signature chain class `ECCBlindSigChain`
- added more tests

src/pyelliptic/__init__.py

@@ -12,6 +12,7 @@ This is an abandoned package maintained inside of the PyBitmessage.
 from .cipher import Cipher
 from .ecc import ECC
 from .eccblind import ECCBlind
+from .eccblindchain import ECCBlindChain
 from .hash import hmac_sha256, hmac_sha512, pbkdf2
 from .openssl import OpenSSL
 
@@ -21,6 +22,7 @@ __all__ = [
     'OpenSSL',
     'ECC',
     'ECCBlind',
+    'ECCBlindChain',
     'Cipher',
     'hmac_sha256',
     'hmac_sha512',

src/pyelliptic/blindchain.py

@@ -1,77 +0,0 @@
-"""
-Blind signature chain with a top level CA
-"""
-
-from eccblind import ECCBlind
-
-try:
-    import msgpack
-except ImportError:
-    try:
-        import umsgpack as msgpack
-    except ImportError:
-        import fallback.umsgpack.umsgpack as msgpack
-
-from eccblind import ECCBlind
-
-def encode_datetime(obj):
-    """
-    Method to format time
-    """
-    return {'Time': int(obj.strftime("%s"))}
-
-
-class ECCBlindChain(object):  # pylint: disable=too-many-instance-attributes
-    """
-    # Class for ECC Blind Chain signature functionality
-    """
-    chain = []
-    ca = []
-
-    def __init__(self, chain=None):
-        if chain is not None:
-            self.chain = chain
-
-    def serialize(self):
-        data = msgpack.packb(self.chain)
-        return data
-
-    @staticmethod
-    def deserialize(self, chain):
-        """
-        Deserialize the data using msgpack
-        """
-        data = msgpack.unpackb(chain)
-        return ECCBlindChain(data)
-
-    def add_level(self, pubkey, metadata, signature):
-        self.chain.append((pubkey, metadata, signature))
-
-    def add_ca(self, ca):
-        pubkey, metadata = ECCBlind.deserialize(ca)
-        self.ca.append(pubkey)
-
-    def verify(self, msg, value):
-        lastpubkey = None
-        retval = False
-        for level in reversed(self.chain):
-            pubkey, metadata, signature = level
-            verifier_obj = ECCBlind(pubkey=pubkey, metadata)
-            if not lastpubkey:
-                retval = verifier_obj.verify(msg, signature, value)
-            else:
-                retval = verifier_obj.verify(lastpubkey, signature, value)
-            if not reval:
-                break
-            lastpubkey = pubkey
-        if retval:
-            retval = False
-            for ca in self.ca:
-                match = True
-                for i in range(4):
-                    if lastpubkey[i] != ca[i]:
-                        match = False
-                        break
-                if match:
-                    return True
-        return retval

src/pyelliptic/eccblind.py

@@ -10,50 +10,69 @@ http://www.isecure-journal.com/article_39171_47f9ec605dd3918c2793565ec21fcd7a.pd
 # variable names are based on the math in the paper, so they don't conform
 # to PEP8
 
-from hashlib import sha256
 import time
-
+from hashlib import sha256
-try:
+from struct import pack, unpack
-    import msgpack
-except ImportError:
-    try:
-        import umsgpack as msgpack
-    except ImportError:
-        import fallback.umsgpack.umsgpack as msgpack
 
 from .openssl import OpenSSL
 
+# first byte in serialisation can contain data
+Y_BIT = 0x01
+COMPRESSED_BIT = 0x02
 
-class Metadata(object):
+# formats
-    """
+BIGNUM = '!32s'
-    Pubkey metadata
+EC = '!B32s'
-    """
+PUBKEY = '!BB33s'
-    def __init__(self, exp=0, value=0):
+
-        self.exp = 0
+
-        self.value = 0
+class Expiration(object):
-        if exp:
+    """Expiration of pubkey"""
-            self.exp = exp
+    @staticmethod
-        if value:
+    def deserialize(val):
+        """Create an object out of int"""
+        year = ((val & 0xF0) >> 4) + 2020
+        month = val & 0x0F
+        assert month < 12
+        return Expiration(year, month)
+
+    def __init__(self, year, month):
+        assert isinstance(year, int)
+        assert year > 2019 and year < 2036
+        assert isinstance(month, int)
+        assert month < 12
+        self.year = year
+        self.month = month
+        self.exp = year + month / 12.0
+
+    def serialize(self):
+        """Make int out of object"""
+        return ((self.year - 2020) << 4) + self.month
+
+    def verify(self):
+        """Check if the pubkey has expired"""
+        now = time.gmtime()
+        return self.exp >= now.tm_year + (now.tm_mon - 1) / 12.0
+
+
+class Value(object):
+    """Value of a pubkey"""
+    @staticmethod
+    def deserialize(val):
+        """Make object out of int"""
+        return Value(val)
+
+    def __init__(self, value=0xFF):
+        assert isinstance(value, int)
         self.value = value
 
     def serialize(self):
-        if self.exp or self.value:
+        """Make int out of object"""
-            return [self.exp, self.value]
+        return self.value & 0xFF
-        else:
-            return []
-
-    @staticmethod
-    def deserialize(self, data):
-        exp, value = data
-        return Medatadata(exp, value)
 
     def verify(self, value):
-        if self.value and value > self.value:
+        """Verify against supplied value"""
-            return False
+        return value <= self.value
-        if self.exp:
-            if time.time() > self.exp:
-                return False
-        return True
 
 
 class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
@@ -64,8 +83,8 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
     # init
     k = None
     R = None
-    keypair = None
     F = None
+    d = None
     Q = None
     a = None
     b = None
@@ -76,70 +95,128 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
     m_ = None
     s_ = None
     signature = None
+    exp = None
+    val = None
 
-    @staticmethod
+    def ec_get_random(self):
-    def ec_get_random(group, ctx):
         """
-        Random point from finite field
+        Random integer within the EC order
         """
-        order = OpenSSL.BN_new()
+        randomnum = OpenSSL.BN_new()
-        OpenSSL.EC_GROUP_get_order(group, order, ctx)
+        OpenSSL.BN_rand(randomnum, OpenSSL.BN_num_bits(self.n), 0, 0)
-        OpenSSL.BN_rand(order, OpenSSL.BN_num_bits(order), 0, 0)
+        return randomnum
-        return order
 
-    @staticmethod
+    def ec_invert(self, a):
-    def ec_invert(group, a, ctx):
         """
         ECC inversion
         """
-        order = OpenSSL.BN_new()
+        inverse = OpenSSL.BN_mod_inverse(0, a, self.n, self.ctx)
-        OpenSSL.EC_GROUP_get_order(group, order, ctx)
-        inverse = OpenSSL.BN_mod_inverse(0, a, order, ctx)
         return inverse
 
-    @staticmethod
+    def ec_gen_keypair(self):
-    def ec_gen_keypair(group, ctx):
         """
         Generate an ECC keypair
+        We're using compressed keys
         """
-        d = ECCBlind.ec_get_random(group, ctx)
+        d = self.ec_get_random()
-        Q = OpenSSL.EC_POINT_new(group)
+        Q = OpenSSL.EC_POINT_new(self.group)
-        OpenSSL.EC_POINT_mul(group, Q, d, 0, 0, 0)
+        OpenSSL.EC_POINT_mul(self.group, Q, d, 0, 0, 0)
         return (d, Q)
 
-    @staticmethod
+    def ec_Ftor(self, F):
-    def ec_Ftor(F, group, ctx):
         """
         x0 coordinate of F
         """
         # F = (x0, y0)
         x0 = OpenSSL.BN_new()
         y0 = OpenSSL.BN_new()
-        OpenSSL.EC_POINT_get_affine_coordinates_GFp(group, F, x0, y0, ctx)
+        OpenSSL.EC_POINT_get_affine_coordinates(self.group, F, x0, y0, self.ctx)
+        OpenSSL.BN_free(y0)
         return x0
 
-    @staticmethod
+    def _ec_point_serialize(self, point):
-    def deserialize(self, data):
+        """Make an EC point into a string"""
-        pubkey_deserialized, meta = msgpack.unpackb(data)
+        try:
-        if meta:
+            x = OpenSSL.BN_new()
-            obj = ECCBlind(pubkey=pubkey_deserialized, metadata=meta)
+            y = OpenSSL.BN_new()
-        else:
+            OpenSSL.EC_POINT_get_affine_coordinates(
-            obj = ECCBlind(pubkey=pubkey_deserialized)
+                self.group, point, x, y, 0)
-        return obj
+            y_byte = (OpenSSL.BN_is_odd(y) & Y_BIT) | COMPRESSED_BIT
+            l_ = OpenSSL.BN_num_bytes(self.n)
+            try:
+                bx = OpenSSL.malloc(0, l_)
+                OpenSSL.BN_bn2binpad(x, bx, l_)
+                out = bx.raw
+            except AttributeError:
+                # padding manually
+                bx = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(x))
+                OpenSSL.BN_bn2bin(x, bx)
+                out = bx.raw.rjust(l_, chr(0))
+            return pack(EC, y_byte, out)
 
-    def serialize(self):
+        finally:
-        data = (self.pubkey, self.metadata.serialize)
+            OpenSSL.BN_clear_free(x)
-        retval = msgpack.packb(data)
+            OpenSSL.BN_clear_free(y)
+
+    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)
+        y_bit &= Y_BIT
+        retval = OpenSSL.EC_POINT_new(self.group)
+        OpenSSL.EC_POINT_set_compressed_coordinates(self.group,
+                                                    retval,
+                                                    x,
+                                                    y_bit,
+                                                    self.ctx)
         return retval
 
-    def __init__(self, curve="secp256k1", pubkey=None, metadata=None):
+    def _bn_serialize(self, bn):
+        """Make a string out of BigNum"""
+        l_ = OpenSSL.BN_num_bytes(self.n)
+        try:
+            o = OpenSSL.malloc(0, l_)
+            OpenSSL.BN_bn2binpad(bn, o, l_)
+            return o.raw
+        except AttributeError:
+            o = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(bn))
+            OpenSSL.BN_bn2bin(bn, o)
+            return o.raw.rjust(l_, chr(0))
+
+    def _bn_deserialize(self, data):
+        """Make a BigNum out of string"""
+        x = OpenSSL.BN_bin2bn(data, OpenSSL.BN_num_bytes(self.n), 0)
+        return x
+
+    def _init_privkey(self, privkey):
+        """Initialise private key out of string/bytes"""
+        self.d = self._bn_deserialize(privkey)
+
+    def privkey(self):
+        """Make a private key into a string"""
+        return pack(BIGNUM, self.d)
+
+    def _init_pubkey(self, pubkey):
+        """Initialise pubkey out of string/bytes"""
+        unpacked = unpack(PUBKEY, pubkey)
+        self.expiration = Expiration.deserialize(unpacked[0])
+        self.value = Value.deserialize(unpacked[1])
+        self.Q = self._ec_point_deserialize(unpacked[2])
+
+    def pubkey(self):
+        """Make a pubkey into a string"""
+        return pack(PUBKEY, self.expiration.serialize(),
+                    self.value.serialize(),
+                    self._ec_point_serialize(self.Q))
+
+    def __init__(self, curve="secp256k1", pubkey=None, privkey=None,  # pylint: disable=too-many-arguments
+                 year=2025, month=11, value=0xFF):
         self.ctx = OpenSSL.BN_CTX_new()
 
-        if pubkey:
+        # ECC group
-            self.group, self.G, self.n, self.Q = pubkey
-        else:
         self.group = OpenSSL.EC_GROUP_new_by_curve_name(
             OpenSSL.get_curve(curve))
+
         # Order n
         self.n = OpenSSL.BN_new()
         OpenSSL.EC_GROUP_get_order(self.group, self.n, self.ctx)
@@ -147,44 +224,54 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
         # Generator G
         self.G = OpenSSL.EC_GROUP_get0_generator(self.group)
 
-            # new keypair
-            self.keypair = ECCBlind.ec_gen_keypair(self.group, self.ctx)
-
-            self.Q = self.keypair[1]
-
-        self.pubkey = (self.group, self.G, self.n, self.Q)
-
         # Identity O (infinity)
         self.iO = OpenSSL.EC_POINT_new(self.group)
         OpenSSL.EC_POINT_set_to_infinity(self.group, self.iO)
 
-        if metadata:
+        if privkey:
-            self._set_metadata(self, metadata)
+            assert pubkey
+            # load both pubkey and privkey from bytes
+            self._init_privkey(privkey)
+            self._init_pubkey(pubkey)
+        elif pubkey:
+            # load pubkey from bytes
+            self._init_pubkey(pubkey)
         else:
-            self.metadata = Metadata()
+            # new keypair
+            self.d, self.Q = self.ec_gen_keypair()
+            if not year or not month:
+                now = time.gmtime()
+                if now.tm_mon == 12:
+                    self.expiration = Expiration(now.tm_year + 1, 1)
+                else:
+                    self.expiration = Expiration(now.tm_year, now.tm_mon + 1)
+            else:
+                self.expiration = Expiration(year, month)
+            self.value = Value(value)
 
-    def _set_metadata(self, metadata):
+    def __del__(self):
-        self.metadata = Metadata.deserialise(metadata)
+        OpenSSL.BN_free(self.n)
+        OpenSSL.BN_CTX_free(self.ctx)
 
     def signer_init(self):
         """
         Init signer
         """
         # Signer: Random integer k
-        self.k = ECCBlind.ec_get_random(self.group, self.ctx)
+        self.k = self.ec_get_random()
 
         # R = kG
         self.R = OpenSSL.EC_POINT_new(self.group)
         OpenSSL.EC_POINT_mul(self.group, self.R, self.k, 0, 0, 0)
 
-        return self.R
+        return self._ec_point_serialize(self.R)
 
     def create_signing_request(self, R, msg):
         """
         Requester creates a new signing request
         """
-        self.R = R
+        self.R = self._ec_point_deserialize(R)
-        msghash = sha256(msg)
+        msghash = sha256(msg).digest()
 
         # Requester: 3 random blinding factors
         self.F = OpenSSL.EC_POINT_new(self.group)
@@ -194,12 +281,12 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
 
         # F != O
         while OpenSSL.EC_POINT_cmp(self.group, self.F, self.iO, self.ctx) == 0:
-            self.a = ECCBlind.ec_get_random(self.group, self.ctx)
+            self.a = self.ec_get_random()
-            self.b = ECCBlind.ec_get_random(self.group, self.ctx)
+            self.b = self.ec_get_random()
-            self.c = ECCBlind.ec_get_random(self.group, self.ctx)
+            self.c = self.ec_get_random()
 
             # F = b^-1 * R...
-            self.binv = ECCBlind.ec_invert(self.group, self.b, self.ctx)
+            self.binv = self.ec_invert(self.b)
             OpenSSL.EC_POINT_mul(self.group, temp, 0, self.R, self.binv, 0)
             OpenSSL.EC_POINT_copy(self.F, temp)
 
@@ -213,7 +300,7 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
             OpenSSL.EC_POINT_add(self.group, self.F, self.F, temp, 0)
 
         # F = (x0, y0)
-        self.r = ECCBlind.ec_Ftor(self.F, self.group, self.ctx)
+        self.r = self.ec_Ftor(self.F)
 
         # Requester: Blinding (m' = br(m) + a)
         self.m = OpenSSL.BN_new()
@@ -223,43 +310,48 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
         OpenSSL.BN_mod_mul(self.m_, self.b, self.r, self.n, self.ctx)
         OpenSSL.BN_mod_mul(self.m_, self.m_, self.m, self.n, self.ctx)
         OpenSSL.BN_mod_add(self.m_, self.m_, self.a, self.n, self.ctx)
-        return self.m_
+        return self._bn_serialize(self.m_)
 
     def blind_sign(self, m_):
         """
         Signer blind-signs the request
         """
-        self.m_ = m_
+        self.m_ = self._bn_deserialize(m_)
         self.s_ = OpenSSL.BN_new()
-        OpenSSL.BN_mod_mul(self.s_, self.keypair[0], self.m_, self.n, self.ctx)
+        OpenSSL.BN_mod_mul(self.s_, self.d, self.m_, self.n, self.ctx)
         OpenSSL.BN_mod_add(self.s_, self.s_, self.k, self.n, self.ctx)
-        return self.s_
+        OpenSSL.BN_free(self.k)
+        return self._bn_serialize(self.s_)
 
     def unblind(self, s_):
         """
         Requester unblinds the signature
         """
-        self.s_ = s_
+        self.s_ = self._bn_deserialize(s_)
         s = OpenSSL.BN_new()
         OpenSSL.BN_mod_mul(s, self.binv, self.s_, self.n, self.ctx)
         OpenSSL.BN_mod_add(s, s, self.c, self.n, self.ctx)
+        OpenSSL.BN_free(self.a)
+        OpenSSL.BN_free(self.b)
+        OpenSSL.BN_free(self.c)
         self.signature = (s, self.F)
-        return self.signature
+        return self._bn_serialize(s) + self._ec_point_serialize(self.F)
 
-    def verify(self, msg, signature, value=0):
+    def verify(self, msg, signature, value=1):
         """
         Verify signature with certifier's pubkey
         """
 
         # convert msg to BIGNUM
         self.m = OpenSSL.BN_new()
-        msghash = sha256(msg)
+        msghash = sha256(msg).digest()
         OpenSSL.BN_bin2bn(msghash, len(msghash), self.m)
 
         # init
-        s, self.F = signature
+        s, self.F = (self._bn_deserialize(signature[0:32]),
+                     self._ec_point_deserialize(signature[32:]))
         if self.r is None:
-            self.r = ECCBlind.ec_Ftor(self.F, self.group, self.ctx)
+            self.r = self.ec_Ftor(self.F)
 
         lhs = OpenSSL.EC_POINT_new(self.group)
         rhs = OpenSSL.EC_POINT_new(self.group)
@@ -273,8 +365,10 @@ class ECCBlind(object):  # pylint: disable=too-many-instance-attributes
         retval = OpenSSL.EC_POINT_cmp(self.group, lhs, rhs, self.ctx)
         if retval == -1:
             raise RuntimeError("EC_POINT_cmp returned an error")
+        elif not self.value.verify(value):
+            return False
+        elif not self.expiration.verify():
+            return False
         elif retval != 0:
             return False
-        elif self.metadata:
-            return self.metadata.verify(value)
         return True

src/pyelliptic/eccblindchain.py

@@ -0,0 +1,52 @@
+"""
+Blind signature chain with a top level CA
+"""
+
+from .eccblind import ECCBlind
+
+
+class ECCBlindChain(object):  # pylint: disable=too-few-public-methods
+    """
+    # Class for ECC Blind Chain signature functionality
+    """
+
+    def __init__(self, ca=None, chain=None):
+        self.chain = []
+        self.ca = []
+        if ca:
+            for i in range(0, len(ca), 35):
+                self.ca.append(ca[i:i + 35])
+        if chain:
+            self.chain.append(chain[0:35])
+            for i in range(35, len(chain), 100):
+                if len(chain[i:]) == 65:
+                    self.chain.append(chain[i:i + 65])
+                else:
+                    self.chain.append(chain[i:i + 100])
+
+    def verify(self, msg, value):
+        """Verify a chain provides supplied message and value"""
+        parent = None
+        l_ = 0
+        for level in self.chain:
+            l_ += 1
+            pubkey = None
+            signature = None
+            if len(level) == 100:
+                pubkey, signature = (level[0:35], level[35:])
+            elif len(level) == 35:
+                if level not in self.ca:
+                    return False
+                parent = level
+                continue
+            else:
+                signature = level
+            verifier_obj = ECCBlind(pubkey=parent)
+            if pubkey:
+                if not verifier_obj.verify(pubkey, signature, value):
+                    return False
+                parent = pubkey
+            else:
+                return verifier_obj.verify(msg=msg, signature=signature,
+                                           value=value)
+        return None

src/pyelliptic/openssl.py

@@ -8,6 +8,7 @@ needed openssl functionality in class _OpenSSL.
 """
 import ctypes
 import sys
+
 # pylint: disable=protected-access
 
 OpenSSL = None
@@ -97,6 +98,10 @@ class _OpenSSL(object):
         self.BN_free.restype = None
         self.BN_free.argtypes = [ctypes.c_void_p]
 
+        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_num_bits = self._lib.BN_num_bits
         self.BN_num_bits.restype = ctypes.c_int
         self.BN_num_bits.argtypes = [ctypes.c_void_p]
@@ -105,6 +110,15 @@ class _OpenSSL(object):
         self.BN_bn2bin.restype = ctypes.c_int
         self.BN_bn2bin.argtypes = [ctypes.c_void_p, 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,
+                                          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.argtypes = [ctypes.c_void_p, ctypes.c_int,
@@ -147,6 +161,20 @@ class _OpenSSL(object):
                                                              ctypes.c_void_p,
                                                              ctypes.c_void_p]
 
+        try:
+            self.EC_POINT_get_affine_coordinates = \
+                self._lib.EC_POINT_get_affine_coordinates
+        except AttributeError:
+            # OpenSSL docs say only use this for backwards compatibility
+            self.EC_POINT_get_affine_coordinates = \
+                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.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,
@@ -171,6 +199,34 @@ class _OpenSSL(object):
                                                              ctypes.c_void_p,
                                                              ctypes.c_void_p]
 
+        try:
+            self.EC_POINT_set_affine_coordinates = \
+                self._lib.EC_POINT_set_affine_coordinates
+        except AttributeError:
+            # OpenSSL docs say only use this for backwards compatibility
+            self.EC_POINT_set_affine_coordinates = \
+                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.c_void_p]
+
+        try:
+            self.EC_POINT_set_compressed_coordinates = \
+                self._lib.EC_POINT_set_compressed_coordinates
+        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.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.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.argtypes = [ctypes.c_void_p]
@@ -215,10 +271,6 @@ class _OpenSSL(object):
             self._lib.ECDH_set_method.argtypes = [ctypes.c_void_p,
                                                   ctypes.c_void_p]
 
-        self.BN_CTX_new = self._lib.BN_CTX_new
-        self._lib.BN_CTX_new.restype = ctypes.c_void_p
-        self._lib.BN_CTX_new.argtypes = []
-
         self.ECDH_compute_key = self._lib.ECDH_compute_key
         self.ECDH_compute_key.restype = ctypes.c_int
         self.ECDH_compute_key.argtypes = [ctypes.c_void_p,
@@ -477,13 +529,19 @@ class _OpenSSL(object):
         self.BN_cmp.argtypes = [ctypes.c_void_p,
                                 ctypes.c_void_p]
 
+        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]
+        except AttributeError:
+            # OpenSSL 1.1.0 implements this as a function, but earlier
+            # versions as macro, so we need to workaround
+            self.BN_is_odd = self.BN_is_odd_compatible
+
         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_CTX_free = self._lib.BN_CTX_free
-        self.BN_CTX_free.argtypes = [ctypes.c_void_p]
-
         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
         self.EC_GROUP_new_by_curve_name.argtypes = [ctypes.c_int]
@@ -600,6 +658,16 @@ class _OpenSSL(object):
         """
         return int((self.BN_num_bits(x) + 7) / 8)
 
+    def BN_is_odd_compatible(self, x):
+        """
+        returns if BN is odd
+        we assume big endianness, and that BN is initialised
+        """
+        length = self.BN_num_bytes(x)
+        data = self.malloc(0, length)
+        OpenSSL.BN_bn2bin(x, data)
+        return ord(data[length - 1]) & 1
+
     def get_cipher(self, name):
         """
         returns the OpenSSL cipher instance

src/tests/test_blindsig.py

@@ -2,14 +2,15 @@
 Test for ECC blind signatures
 """
 import os
-import time
 import unittest
-from ctypes import cast, c_char_p
+from hashlib import sha256
 
-from pybitmessage.pyelliptic.eccblind import ECCBlind, Metadata
+from pybitmessage.pyelliptic.eccblind import ECCBlind
 from pybitmessage.pyelliptic.eccblindchain import ECCBlindChain
 from pybitmessage.pyelliptic.openssl import OpenSSL
 
+# pylint: disable=protected-access
+
 
 class TestBlindSig(unittest.TestCase):
     """
@@ -21,78 +22,255 @@ class TestBlindSig(unittest.TestCase):
         # (1) Initialization
         signer_obj = ECCBlind()
         point_r = signer_obj.signer_init()
+        self.assertEqual(len(signer_obj.pubkey()), 35)
 
         # (2) Request
-        requester_obj = ECCBlind(pubkey=signer_obj.pubkey)
+        requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
         # only 64 byte messages are planned to be used in Bitmessage
         msg = os.urandom(64)
         msg_blinded = requester_obj.create_signing_request(point_r, msg)
+        self.assertEqual(len(msg_blinded), 32)
 
         # check
-        msg_blinded_str = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(msg_blinded))
+        self.assertNotEqual(sha256(msg).digest(), msg_blinded)
-        OpenSSL.BN_bn2bin(msg_blinded, msg_blinded_str)
-        self.assertNotEqual(msg, cast(msg_blinded_str, c_char_p).value)
 
         # (3) Signature Generation
         signature_blinded = signer_obj.blind_sign(msg_blinded)
+        assert isinstance(signature_blinded, str)
+        self.assertEqual(len(signature_blinded), 32)
 
         # (4) Extraction
         signature = requester_obj.unblind(signature_blinded)
+        assert isinstance(signature, str)
+        self.assertEqual(len(signature), 65)
 
-        # check
+        self.assertNotEqual(signature, signature_blinded)
-        signature_blinded_str = OpenSSL.malloc(0,
-                                               OpenSSL.BN_num_bytes(
-                                                   signature_blinded))
-        signature_str = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(signature[0]))
-        OpenSSL.BN_bn2bin(signature_blinded, signature_blinded_str)
-        OpenSSL.BN_bn2bin(signature[0], signature_str)
-        self.assertNotEqual(cast(signature_str, c_char_p).value,
-                            cast(signature_blinded_str, c_char_p).value)
 
         # (5) Verification
-        verifier_obj = ECCBlind(pubkey=signer_obj.pubkey)
+        verifier_obj = ECCBlind(pubkey=signer_obj.pubkey())
         self.assertTrue(verifier_obj.verify(msg, signature))
 
-        # Serialization and deserialisation
+    def test_is_odd(self):
-        pk = signer_obj.serialize()
+        """Test our implementation of BN_is_odd"""
-        pko = ECCBlind.deserialize(pk)
+        for _ in range(1024):
-        self.assertTrue(pko.verify(msg, signature))
+            obj = ECCBlind()
+            x = OpenSSL.BN_new()
+            y = OpenSSL.BN_new()
+            OpenSSL.EC_POINT_get_affine_coordinates(
+                obj.group, obj.Q, x, y, 0)
+            self.assertEqual(OpenSSL.BN_is_odd(y),
+                             OpenSSL.BN_is_odd_compatible(y))
 
-    def test_blind_sig_chain(self):
+    def test_serialize_ec_point(self):
+        """Test EC point serialization/deserialization"""
+        for _ in range(1024):
+            try:
+                obj = ECCBlind()
+                obj2 = ECCBlind()
+                randompoint = obj.Q
+                serialized = obj._ec_point_serialize(randompoint)
+                secondpoint = obj2._ec_point_deserialize(serialized)
+                x0 = OpenSSL.BN_new()
+                y0 = OpenSSL.BN_new()
+                OpenSSL.EC_POINT_get_affine_coordinates(obj.group,
+                                                        randompoint, x0,
+                                                        y0, obj.ctx)
+                x1 = OpenSSL.BN_new()
+                y1 = OpenSSL.BN_new()
+                OpenSSL.EC_POINT_get_affine_coordinates(obj2.group,
+                                                        secondpoint, x1,
+                                                        y1, obj2.ctx)
+
+                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)
+            finally:
+                OpenSSL.BN_free(x0)
+                OpenSSL.BN_free(x1)
+                OpenSSL.BN_free(y0)
+                OpenSSL.BN_free(y1)
+                del obj
+                del obj2
+
+    def test_serialize_bn(self):
+        """Test Bignum serialization/deserialization"""
+        for _ in range(1024):
+            obj = ECCBlind()
+            obj2 = ECCBlind()
+            randomnum = obj.d
+            serialized = obj._bn_serialize(randomnum)
+            secondnum = obj2._bn_deserialize(serialized)
+            self.assertEqual(OpenSSL.BN_cmp(randomnum, secondnum), 0)
+
+    def test_blind_sig_many(self):
+        """Test a lot of blind signatures"""
+        for _ in range(1024):
+            self.test_blind_sig()
+
+    def test_blind_sig_value(self):
+        """Test blind signature value checking"""
+        signer_obj = ECCBlind(value=5)
+        point_r = signer_obj.signer_init()
+        requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
+        msg = os.urandom(64)
+        msg_blinded = requester_obj.create_signing_request(point_r, msg)
+        signature_blinded = signer_obj.blind_sign(msg_blinded)
+        signature = requester_obj.unblind(signature_blinded)
+        verifier_obj = ECCBlind(pubkey=signer_obj.pubkey())
+        self.assertFalse(verifier_obj.verify(msg, signature, value=8))
+
+    def test_blind_sig_expiration(self):
+        """Test blind signature expiration checking"""
+        signer_obj = ECCBlind(year=2020, month=1)
+        point_r = signer_obj.signer_init()
+        requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
+        msg = os.urandom(64)
+        msg_blinded = requester_obj.create_signing_request(point_r, msg)
+        signature_blinded = signer_obj.blind_sign(msg_blinded)
+        signature = requester_obj.unblind(signature_blinded)
+        verifier_obj = ECCBlind(pubkey=signer_obj.pubkey())
+        self.assertFalse(verifier_obj.verify(msg, signature))
+
+    def test_blind_sig_chain(self):  # pylint: disable=too-many-locals
         """Test blind signature chain using a random certifier key and a random message"""
 
-        test_levels = 5
+        test_levels = 4
-        value = 1
         msg = os.urandom(1024)
 
-        chain = ECCBlindChain()
         ca = ECCBlind()
         signer_obj = ca
-        signer_pubkey = signer_obj.serialize()
+
+        output = bytearray()
 
         for level in range(test_levels):
-            if level == 0:
+            if not level:
-                metadata = Metadata(exp=int(time.time()) + 100,
+                output.extend(ca.pubkey())
-                                    value=value).serialize()
+            requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
-                requester_obj = ECCBlind(pubkey=signer_obj.pubkey,
+            child_obj = ECCBlind()
-                                         metadata=metadata)
-            else:
-                requester_obj = ECCBlind(pubkey=signer_obj.pubkey)
             point_r = signer_obj.signer_init()
+            pubkey = child_obj.pubkey()
 
             if level == test_levels - 1:
                 msg_blinded = requester_obj.create_signing_request(point_r,
                                                                    msg)
             else:
-                msg_blinded = requester.obj.create_signing_request(point_r,
+                msg_blinded = requester_obj.create_signing_request(point_r,
-                                                                   signer_pubkey)
+                                                                   pubkey)
             signature_blinded = signer_obj.blind_sign(msg_blinded)
             signature = requester_obj.unblind(signature_blinded)
-            chain.add_level(signer_obj.pubkey,
+            if level != test_levels - 1:
-                            signer_obj.metadata.serialize,
+                output.extend(pubkey)
-                            signature)
+            output.extend(signature)
-            signer_obj = requester_obj
+            signer_obj = child_obj
-            signer_pubkey = requester_obj.serialize()
+        verifychain = ECCBlindChain(ca=ca.pubkey(), chain=str(output))
-        sigchain = chain.serialize()
+        self.assertTrue(verifychain.verify(msg=msg, value=1))
-        verifychain = ECCBlindChain.deserialize(sigchain)
+
-        self.assertTrue(verifychain.verify(msg, value))
+    def test_blind_sig_chain_wrong_ca(self):  # pylint: disable=too-many-locals
+        """Test blind signature chain with an unlisted ca"""
+
+        test_levels = 4
+        msg = os.urandom(1024)
+
+        ca = ECCBlind()
+        fake_ca = ECCBlind()
+        signer_obj = fake_ca
+
+        output = bytearray()
+
+        for level in range(test_levels):
+            requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
+            child_obj = ECCBlind()
+            if not level:
+                # unlisted CA, but a syntactically valid pubkey
+                output.extend(fake_ca.pubkey())
+            point_r = signer_obj.signer_init()
+            pubkey = child_obj.pubkey()
+
+            if level == test_levels - 1:
+                msg_blinded = requester_obj.create_signing_request(point_r,
+                                                                   msg)
+            else:
+                msg_blinded = requester_obj.create_signing_request(point_r,
+                                                                   pubkey)
+            signature_blinded = signer_obj.blind_sign(msg_blinded)
+            signature = requester_obj.unblind(signature_blinded)
+            if level != test_levels - 1:
+                output.extend(pubkey)
+            output.extend(signature)
+            signer_obj = child_obj
+        verifychain = ECCBlindChain(ca=ca.pubkey(), chain=str(output))
+        self.assertFalse(verifychain.verify(msg, 1))
+
+    def test_blind_sig_chain_wrong_msg(self):  # pylint: disable=too-many-locals
+        """Test blind signature chain with a fake message"""
+
+        test_levels = 4
+        msg = os.urandom(1024)
+        fake_msg = os.urandom(1024)
+
+        ca = ECCBlind()
+        signer_obj = ca
+
+        output = bytearray()
+
+        for level in range(test_levels):
+            if not level:
+                output.extend(ca.pubkey())
+            requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
+            child_obj = ECCBlind()
+            point_r = signer_obj.signer_init()
+            pubkey = child_obj.pubkey()
+
+            if level == test_levels - 1:
+                msg_blinded = requester_obj.create_signing_request(point_r,
+                                                                   msg)
+            else:
+                msg_blinded = requester_obj.create_signing_request(point_r,
+                                                                   pubkey)
+            signature_blinded = signer_obj.blind_sign(msg_blinded)
+            signature = requester_obj.unblind(signature_blinded)
+            if level != test_levels - 1:
+                output.extend(pubkey)
+            output.extend(signature)
+            signer_obj = child_obj
+        verifychain = ECCBlindChain(ca=ca.pubkey(), chain=str(output))
+        self.assertFalse(verifychain.verify(fake_msg, 1))
+
+    def test_blind_sig_chain_wrong_intermediary(self):  # pylint: disable=too-many-locals
+        """Test blind signature chain using a fake intermediary pubkey"""
+
+        test_levels = 4
+        msg = os.urandom(1024)
+        wrong_level = 2
+
+        ca = ECCBlind()
+        signer_obj = ca
+        fake_intermediary = ECCBlind()
+
+        output = bytearray()
+
+        for level in range(test_levels):
+            if not level:
+                output.extend(ca.pubkey())
+            requester_obj = ECCBlind(pubkey=signer_obj.pubkey())
+            child_obj = ECCBlind()
+            point_r = signer_obj.signer_init()
+            pubkey = child_obj.pubkey()
+
+            if level == test_levels - 1:
+                msg_blinded = requester_obj.create_signing_request(point_r,
+                                                                   msg)
+            else:
+                msg_blinded = requester_obj.create_signing_request(point_r,
+                                                                   pubkey)
+            signature_blinded = signer_obj.blind_sign(msg_blinded)
+            signature = requester_obj.unblind(signature_blinded)
+            if level == wrong_level:
+                output.extend(fake_intermediary.pubkey())
+            elif level != test_levels - 1:
+                output.extend(pubkey)
+            output.extend(signature)
+            signer_obj = child_obj
+        verifychain = ECCBlindChain(ca=ca.pubkey(), chain=str(output))
+        self.assertFalse(verifychain.verify(msg, 1))

src/tests/test_openssl.py

@@ -0,0 +1,54 @@
+"""
+Test if OpenSSL is working correctly
+"""
+import unittest
+
+from pybitmessage.pyelliptic.openssl import OpenSSL
+
+try:
+    OpenSSL.BN_bn2binpad
+    have_pad = True
+except AttributeError:
+    have_pad = None
+
+
+class TestOpenSSL(unittest.TestCase):
+    """
+    Test cases for OpenSSL
+    """
+    def test_is_odd(self):
+        """Test BN_is_odd implementation"""
+        ctx = OpenSSL.BN_CTX_new()
+        a = OpenSSL.BN_new()
+        group = OpenSSL.EC_GROUP_new_by_curve_name(
+            OpenSSL.get_curve("secp256k1"))
+        OpenSSL.EC_GROUP_get_order(group, a, ctx)
+
+        bad = 0
+        for _ in range(1024):
+            OpenSSL.BN_rand(a, OpenSSL.BN_num_bits(a), 0, 0)
+            if not OpenSSL.BN_is_odd(a) == OpenSSL.BN_is_odd_compatible(a):
+                bad += 1
+        self.assertEqual(bad, 0)
+
+    @unittest.skipUnless(have_pad, 'Skipping OpenSSL pad test')
+    def test_padding(self):
+        """Test an alternatie implementation of bn2binpad"""
+
+        ctx = OpenSSL.BN_CTX_new()
+        a = OpenSSL.BN_new()
+        n = OpenSSL.BN_new()
+        group = OpenSSL.EC_GROUP_new_by_curve_name(
+            OpenSSL.get_curve("secp256k1"))
+        OpenSSL.EC_GROUP_get_order(group, n, ctx)
+
+        bad = 0
+        for _ in range(1024):
+            OpenSSL.BN_rand(a, OpenSSL.BN_num_bits(n), 0, 0)
+            b = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(n))
+            c = OpenSSL.malloc(0, OpenSSL.BN_num_bytes(a))
+            OpenSSL.BN_bn2binpad(a, b, OpenSSL.BN_num_bytes(n))
+            OpenSSL.BN_bn2bin(a, c)
+            if b.raw != c.raw.rjust(OpenSSL.BN_num_bytes(n), chr(0)):
+                bad += 1
+        self.assertEqual(bad, 0)