diff options
Diffstat (limited to 'pyecsca/ec/mult.py')
| -rw-r--r-- | pyecsca/ec/mult.py | 35 |
1 files changed, 30 insertions, 5 deletions
diff --git a/pyecsca/ec/mult.py b/pyecsca/ec/mult.py index 4dd0f5b..a32a54b 100644 --- a/pyecsca/ec/mult.py +++ b/pyecsca/ec/mult.py @@ -1,9 +1,9 @@ from copy import copy -from typing import Mapping +from typing import Mapping, Tuple from .context import Context from .curve import EllipticCurve -from .formula import Formula, AdditionFormula, DoublingFormula, ScalingFormula +from .formula import Formula, AdditionFormula, DoublingFormula, ScalingFormula, LadderFormula from .point import Point @@ -30,19 +30,25 @@ class ScalarMultiplier(object): return copy(other) if other == self.curve.neutral: return copy(one) - return self.context.execute(self.formulas["add"], one, other, **self.curve.parameters) + return self.context.execute(self.formulas["add"], one, other, **self.curve.parameters)[0] def _dbl(self, point: Point) -> Point: if "dbl" not in self.formulas: raise NotImplementedError if point == self.curve.neutral: return copy(point) - return self.context.execute(self.formulas["dbl"], point, **self.curve.parameters) + return self.context.execute(self.formulas["dbl"], point, **self.curve.parameters)[0] def _scl(self, point: Point) -> Point: if "scl" not in self.formulas: raise NotImplementedError - return self.context.execute(self.formulas["scl"], point, **self.curve.parameters) + return self.context.execute(self.formulas["scl"], point, **self.curve.parameters)[0] + + def _ladd(self, start: Point, to_dbl: Point, to_add: Point) -> Tuple[Point, Point]: + if "ladd" not in self.formulas: + raise NotImplementedError + return self.context.execute(self.formulas["ladd"], start, to_dbl, to_add, + **self.curve.parameters) def multiply(self, scalar: int, point: Point) -> Point: raise NotImplementedError @@ -91,3 +97,22 @@ class RTLMultiplier(ScalarMultiplier): if "scl" in self.formulas: r = self._scl(r) return r + + +class LadderMultiplier(ScalarMultiplier): + + def __init__(self, curve: EllipticCurve, ladd: LadderFormula, scl: ScalingFormula = None, + ctx: Context = None): + super().__init__(curve, ctx, ladd=ladd, scl=scl) + + def multiply(self, scalar: int, point: Point) -> Point: + p0 = copy(point) + p1 = self._ladd(self.curve.neutral, point, point)[1] + for i in range(scalar.bit_length(), -1, -1): + if scalar & i != 0: + p0, p1 = self._ladd(point, p1, p0) + else: + p0, p1 = self._ladd(point, p0, p1) + if "scl" in self.formulas: + p0 = self._scl(p0) + return p0 |