X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=pygost%2Fgost3410.py;h=a2cc7cef015507d4db84955cd4a9b9ea392adf29;hb=f3a3246bc9da027e0527b89204e1b95ed52af5c6;hp=9f0a11e656689745056b8f7c53cdf5c3779201b3;hpb=2bb1a163d32e4167e6904ff3c6b4cf64ea7287bb;p=pygost.git

diff --git a/pygost/gost3410.py b/pygost/gost3410.py
index 9f0a11e..a2cc7ce 100644
--- a/pygost/gost3410.py
+++ b/pygost/gost3410.py
@@ -13,7 +13,7 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-""" GOST R 34.10 public-key signature function.
+"""GOST R 34.10 public-key signature function.
 
 This is implementation of GOST R 34.10-2001 (:rfc:`5832`), GOST R
 34.10-2012 (:rfc:`7091`). The difference between 2001 and 2012 is the
@@ -28,14 +28,14 @@ from pygost.utils import long2bytes
 from pygost.utils import modinvert
 
 
-MODE2SIZE = {
-    2001: 32,
-    2012: 64,
-}
+def point_size(point):
+    """Determine is it either 256 or 512 bit point
+    """
+    return (512 // 8) if point.bit_length() > 256 else (256 // 8)
 
 
 class GOST3410Curve(object):
-    """ GOST 34.10 validated curve
+    """GOST 34.10 validated curve
 
     >>> curve = CURVES["id-GostR3410-2001-TestParamSet"]
     >>> prv = prv_unmarshal(urandom(32))
@@ -64,12 +64,14 @@ class GOST3410Curve(object):
         self.cofactor = cofactor
         self.e = e
         self.d = d
-        r1 = self.y * self.y % self.p
-        r2 = ((self.x * self.x + self.a) * self.x + self.b) % self.p
-        if r1 != self.pos(r2):
+        if not self.contains((x, y)):
             raise ValueError("Invalid parameters")
         self._st = None
 
+    @property
+    def point_size(self):
+        return point_size(self.p)
+
     def pos(self, v):
         """Make positive number
         """
@@ -77,6 +79,16 @@ class GOST3410Curve(object):
             return v + self.p
         return v
 
+    def contains(self, point):
+        """Is point on the curve?
+
+        :type point: (long, long)
+        """
+        x, y = point
+        r1 = y * y % self.p
+        r2 = ((x * x + self.a) * x + self.b) % self.p
+        return r1 == self.pos(r2)
+
     def _add(self, p1x, p1y, p2x, p2y):
         if p1x == p2x and p1y == p2y:
             # double
@@ -215,7 +227,7 @@ DEFAULT_CURVE = CURVES["id-GostR3410-2001-CryptoPro-A-ParamSet"]
 
 
 def public_key(curve, prv):
-    """ Generate public key from the private one
+    """Generate public key from the private one
 
     :param GOST3410Curve curve: curve to use
     :param long prv: private key
@@ -225,8 +237,8 @@ def public_key(curve, prv):
     return curve.exp(prv)
 
 
-def sign(curve, prv, digest, rand=None, mode=2001):
-    """ Calculate signature for provided digest
+def sign(curve, prv, digest, rand=None):
+    """Calculate signature for provided digest
 
     :param GOST3410Curve curve: curve to use
     :param long prv: private key
@@ -237,7 +249,7 @@ def sign(curve, prv, digest, rand=None, mode=2001):
     :returns: signature, BE(S) || BE(R)
     :rtype: bytes, 64 or 128 bytes
     """
-    size = MODE2SIZE[mode]
+    size = curve.point_size
     q = curve.q
     e = bytes2long(digest) % q
     if e == 0:
@@ -263,8 +275,8 @@ def sign(curve, prv, digest, rand=None, mode=2001):
     return long2bytes(s, size) + long2bytes(r, size)
 
 
-def verify(curve, pub, digest, signature, mode=2001):
-    """ Verify provided digest with the signature
+def verify(curve, pub, digest, signature):
+    """Verify provided digest with the signature
 
     :param GOST3410Curve curve: curve to use
     :type pub: (long, long)
@@ -274,7 +286,7 @@ def verify(curve, pub, digest, signature, mode=2001):
     :type signature: bytes, 64 or 128 bytes
     :rtype: bool
     """
-    size = MODE2SIZE[mode]
+    size = curve.point_size
     if len(signature) != size * 2:
         raise ValueError("Invalid signature length")
     q = curve.q
@@ -316,25 +328,25 @@ def prv_unmarshal(prv):
     return bytes2long(prv[::-1])
 
 
-def pub_marshal(pub, mode=2001):
+def pub_marshal(pub):
     """Marshal public key
 
     :type pub: (long, long)
     :rtype: bytes
     :returns: LE(X) || LE(Y)
     """
-    size = MODE2SIZE[mode]
+    size = point_size(pub[0])
     return (long2bytes(pub[1], size) + long2bytes(pub[0], size))[::-1]
 
 
-def pub_unmarshal(pub, mode=2001):
+def pub_unmarshal(pub):
     """Unmarshal public key
 
     :param pub: LE(X) || LE(Y)
     :type pub: bytes
     :rtype: (long, long)
     """
-    size = MODE2SIZE[mode]
+    size = len(pub) // 2
     pub = pub[::-1]
     return (bytes2long(pub[size:]), bytes2long(pub[:size]))