def generate_for_nist(self, size):
'''Generate public key.'''
if str(size) not in ['192', '224', '256', '384', '521']:
raise ValueError, 'Can only use nist curves.'
else:
self.size = str(size)
self.ec = nist(self.size)
# secret integer s
self.s = randint(10, self.ec.modulus)
self.b = self.s * self.ec.base_point
def from_file(self, filename, key_type):
'''
Read public or private key (depending on key_type) from file. The file is
ascii and the first line contains the curve size; i) if key_type is private
then it has the secret key s (base 10) in the second line, and ii) if
key_type is public the other three lines contain the x, y and z coordinate
of point B respectively (base 10).
'''
f = open(filename, 'r')
# read curve size
line = f.readline().strip()
if line not in ['192', '224', '256', '384', '521']:
raise BadKeyFile, 'Cannot read curve.'
else:
self.size = line
self.ec = nist(line)
if key_type == 'public':
coords = [] # coordinates
for i in range(3):
line = f.readline().strip()
try:
coords.append(int(line, 10))
except ValueError:
raise BadKeyFile, 'Cannot read point coordinates.'
self.b = self.ec.point(*coords)
elif key_type == 'private':
line = f.readline().strip()
try:
self.s = int(line, 10)
self.b = self.s * self.ec.base_point
except ValueError:
raise BadKeyFile, 'Cannot read secret integer s.'
def setUp(self):
self.ec = EllipticCurve(10, 5, 13)
self.nist = nist(192)
