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0d481fa Jun 8, 2015
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#!/usr/bin/env python3
# This script makes use of another module: common.py, which can be
# found on GitHub:
#
# https://github.com/andreacorbellini/ecc/blob/master/logs/common.py
#
# You must place that module on the same directory of this script
# prior to running it.
import random
from common import tinycurve as curve
def log(p, q):
assert curve.is_on_curve(p)
assert curve.is_on_curve(q)
start = random.randrange(curve.n)
r = curve.mult(start, p)
for x in range(curve.n):
if q == r:
logarithm = (start + x) % curve.n
steps = x + 1
return logarithm, steps
r = curve.add(r, p)
raise AssertionError('logarithm not found')
def main():
x = random.randrange(curve.n)
p = curve.g
q = curve.mult(x, p)
print('Curve: {}'.format(curve))
print('Curve order: {}'.format(curve.n))
print('p = (0x{:x}, 0x{:x})'.format(*p))
print('q = (0x{:x}, 0x{:x})'.format(*q))
print(x, '* p = q')
y, steps = log(p, q)
print('log(p, q) =', y)
print('Took', steps, 'steps')
assert x == y
if __name__ == '__main__':
main()