blob: 32abb45207da98c614c159d6377acc705631f747 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
"""
Provides functionality inspired by the Exceptional Procedure Attack [EPA]_.
"""
from typing import Callable, Literal, Union
from public import public
from pyecsca.ec.point import Point
from pyecsca.sca.re.rpa import MultipleContext
@public
def errors_out(
ctx: MultipleContext,
out: Point,
check_funcs: dict[str, Callable],
check_condition: Union[Literal["all"], Literal["necessary"]],
precomp_to_affine: bool,
) -> bool:
"""
:param ctx: The context containing the points and formulas.
:param out: The output point to check.
:param check_funcs:
:param check_condition:
:param precomp_to_affine:
:return:
.. note::
The scalar multiplier must not short-circuit.
"""
affine_points = {out, *ctx.precomp.values()} if precomp_to_affine else {out}
if check_condition == "all":
points = set(ctx.points.keys())
elif check_condition == "necessary":
points = set(affine_points)
queue = set(affine_points)
while queue:
point = queue.pop()
for parent in ctx.parents[point]:
points.add(parent)
queue.add(parent)
else:
raise ValueError("check_condition must be 'all' or 'necessary'")
# Special case the "to affine" transform and checks
# This actually passes the multiple itself to the check, not the inputs(parents)
for point in affine_points:
if "affine" in check_funcs:
func = check_funcs["affine"]
if func(ctx.points[point]):
return True
# Now handle the regular checks
for point in points:
formula = ctx.formulas[point]
if formula in check_funcs:
func = check_funcs[formula]
inputs = list(map(lambda pt: ctx.points[pt], ctx.parents[point]))
if func(*inputs):
return True
return False
|
