diff options
Diffstat (limited to 'pyecsca/ec/countermeasures.py')
| -rw-r--r-- | pyecsca/ec/countermeasures.py | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/pyecsca/ec/countermeasures.py b/pyecsca/ec/countermeasures.py index a310ce4..86f7177 100644 --- a/pyecsca/ec/countermeasures.py +++ b/pyecsca/ec/countermeasures.py @@ -1,7 +1,7 @@ """Provides several countermeasures against side-channel attacks.""" from abc import ABC, abstractmethod -from typing import Optional +from typing import Optional, Callable from public import public @@ -30,8 +30,13 @@ class ScalarMultiplierCountermeasure(ABC): bits: Optional[int] """The bit-length to use, if any.""" - def __init__(self, mult: "ScalarMultiplier | ScalarMultiplierCountermeasure"): + def __init__( + self, + mult: "ScalarMultiplier | ScalarMultiplierCountermeasure", + rng: Callable[[int], Mod] = Mod.random, + ): self.mult = mult + self.rng = rng def init(self, params: DomainParameters, point: Point, bits: Optional[int] = None): """Initialize the countermeasure with the parameters and the point.""" @@ -76,13 +81,14 @@ class GroupScalarRandomization(ScalarMultiplierCountermeasure): def __init__( self, mult: "ScalarMultiplier | ScalarMultiplierCountermeasure", + rng: Callable[[int], Mod] = Mod.random, rand_bits: int = 32, ): """ :param mult: The multiplier to use. :param rand_bits: How many random bits to sample. """ - super().__init__(mult) + super().__init__(mult, rng) self.rand_bits = rand_bits def multiply(self, scalar: int) -> Point: @@ -90,7 +96,7 @@ class GroupScalarRandomization(ScalarMultiplierCountermeasure): raise ValueError("Not initialized.") with ScalarMultiplicationAction(self.point, self.params, scalar) as action: order = self.params.order - mask = int(Mod.random(1 << self.rand_bits)) + mask = int(self.rng(1 << self.rand_bits)) masked_scalar = scalar + mask * order bits = max(self.bits, self.rand_bits + order.bit_length()) + 1 self.mult.init( @@ -121,13 +127,14 @@ class AdditiveSplitting(ScalarMultiplierCountermeasure): def __init__( self, mult: "ScalarMultiplier | ScalarMultiplierCountermeasure", + rng: Callable[[int], Mod] = Mod.random, add: Optional[AdditionFormula] = None, ): """ :param mult: The multiplier to use. :param add: Addition formula to use, if None, the formula from the multiplier is used. """ - super().__init__(mult) + super().__init__(mult, rng) self.add = add def _add(self, R: Point, S: Point) -> Point: # noqa @@ -146,7 +153,7 @@ class AdditiveSplitting(ScalarMultiplierCountermeasure): raise ValueError("Not initialized.") with ScalarMultiplicationAction(self.point, self.params, scalar) as action: order = self.params.order - r = Mod.random(order) + r = self.rng(order) s = scalar - r bits = max(self.bits, order.bit_length()) self.mult.init(self.params, self.point, bits) @@ -177,20 +184,21 @@ class MultiplicativeSplitting(ScalarMultiplierCountermeasure): def __init__( self, mult: "ScalarMultiplier | ScalarMultiplierCountermeasure", + rng: Callable[[int], Mod] = Mod.random, rand_bits: int = 32, ): """ :param mult: The multiplier to use. :param rand_bits: How many random bits to sample. """ - super().__init__(mult) + super().__init__(mult, rng) self.rand_bits = rand_bits def multiply(self, scalar: int) -> Point: if self.params is None or self.point is None or self.bits is None: raise ValueError("Not initialized.") with ScalarMultiplicationAction(self.point, self.params, scalar) as action: - r = Mod.random(1 << self.rand_bits) + r = self.rng(1 << self.rand_bits) self.mult.init(self.params, self.point, self.rand_bits) R = self.mult.multiply(int(r)) @@ -225,13 +233,14 @@ class EuclideanSplitting(ScalarMultiplierCountermeasure): def __init__( self, mult: "ScalarMultiplier | ScalarMultiplierCountermeasure", + rng: Callable[[int], Mod] = Mod.random, add: Optional[AdditionFormula] = None, ): """ :param mult: The multiplier to use. :param add: Addition formula to use, if None, the formula from the multiplier is used. """ - super().__init__(mult) + super().__init__(mult, rng) self.add = add def _add(self, R: Point, S: Point) -> Point: # noqa @@ -250,7 +259,7 @@ class EuclideanSplitting(ScalarMultiplierCountermeasure): raise ValueError("Not initialized.") with ScalarMultiplicationAction(self.point, self.params, scalar) as action: half_bits = self.bits // 2 - r = Mod.random(1 << half_bits) + r = self.rng(1 << half_bits) self.mult.init(self.params, self.point, half_bits) R = self.mult.multiply(int(r)) # r bounded by half_bits @@ -259,7 +268,9 @@ class EuclideanSplitting(ScalarMultiplierCountermeasure): T = self.mult.multiply(k1) # k1 bounded by half_bits self.mult.init(self.params, R, self.bits) - S = self.mult.multiply(k2) # k2 (in worst case) bounded by bits, but in practice closer to half_bits + S = self.mult.multiply( + k2 + ) # k2 (in worst case) bounded by bits, but in practice closer to half_bits res = self._add(S, T) return action.exit(res) |