forked from jesperborgstrup/Py-EC
/
point.py
120 lines (102 loc) · 4.3 KB
/
point.py
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# MIT License
#
# Copyright (C) 2014 Jesper Borgstrup
# -------------------------------------------------------------------
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
import ctypes
from pyelliptic.openssl import OpenSSL
from echelper import ECHelper
import curve as ec_curve
import bignum as ec_bignum
class Point:
'''
classdocs
'''
def __init__(self, curve, openssl_point=None, x=None, y=None):
'''
Constructor
'''
if not isinstance( curve, ec_curve.Curve ):
raise Exception( 'Provided curve is not a Curve object' )
self.curve = curve
self.os_group = curve.os_group
if openssl_point is not None:
self.__set_to_openssl_point( openssl_point )
elif x is not None and y is not None:
self.__set_to_coordinates( x, y )
else:
raise Exception( 'No point given' )
def __set_to_openssl_point(self, point):
try:
x, y = ec_bignum.BigNum(), ec_bignum.BigNum()
# Put X and Y coordinates of public key into x and y vars
OpenSSL.EC_POINT_get_affine_coordinates_GFp( self.os_group, point, x.bn, y.bn, None )
self.x, self.y = x.get_value(), y.get_value()
self.os_point = point
finally:
del x, y
def __set_to_coordinates(self, x_val, y_val):
try:
point= OpenSSL.EC_POINT_new( self.os_group )
x, y = ec_bignum.BigNum( decval=x_val ), ec_bignum.BigNum( decval=y_val )
if self.curve.field_type == 'prime':
OpenSSL.EC_POINT_set_affine_coordinates_GFp( self.os_group, point, x.bn, y.bn, None )
elif self.curve.field_type == 'characteristic-two':
OpenSSL.EC_POINT_set_affine_coordinates_GF2m( self.os_group, point, x.bn, y.bn, None )
self.x, self.y = x_val, y_val
self.os_point = point
finally:
del x, y
def __eq__(self, other):
if type(other) is type(self):
return self.x == other.x and self.y == other.y
return False
def __ne__(self, other):
return not self.__eq__(other)
def __add__(self, other):
"""
Add two EC points together
"""
if isinstance( other, Point ):
result = OpenSSL.EC_POINT_new( self.os_group )
OpenSSL.EC_POINT_add( self.os_group, result, self.os_point, other.os_point, 0 )
return Point( self.curve, openssl_point=result )
else:
return NotImplemented
def __mul__(self, other):
"""
Multiply an EC point by a scalar value
and returns the multiplication result
"""
if isinstance( other, int ) or isinstance( other, long ):
try:
o = ec_bignum.BigNum( decval=other )
result = OpenSSL.EC_POINT_new( self.os_group )
OpenSSL.EC_POINT_mul( self.os_group, result, 0, self.os_point, o.bn, 0 )
return Point( self.curve, openssl_point=result )
finally:
del o
else:
return NotImplemented
__rmul__ = __mul__
def __str__(self):
return "Point<0x%X, 0x%X>" % ( self.x, self.y )
__repr__ = __str__