diff options
| -rw-r--r-- | pyecsca/ec/divpoly.py | 7 | ||||
| -rw-r--r-- | pyecsca/sca/re/zvp.py | 3 |
2 files changed, 6 insertions, 4 deletions
diff --git a/pyecsca/ec/divpoly.py b/pyecsca/ec/divpoly.py index c66d75d..6621b76 100644 --- a/pyecsca/ec/divpoly.py +++ b/pyecsca/ec/divpoly.py @@ -1,7 +1,7 @@ """ Provides functions for computing division polynomials and the multiplication-by-n map on an elliptic curve. """ -from typing import Tuple, Dict, Set, Mapping +from typing import Tuple, Dict, Set, Mapping, Optional from public import public from sympy import symbols, FF, Poly @@ -203,12 +203,13 @@ def divpoly(curve: EllipticCurve, n: int, two_torsion_multiplicity: int = 2) -> @public -def mult_by_n(curve: EllipticCurve, n: int) -> Tuple[Tuple[Poly, Poly], Tuple[Poly, Poly]]: +def mult_by_n(curve: EllipticCurve, n: int, x_only: bool = False) -> Tuple[Tuple[Poly, Poly], Optional[Tuple[Poly, Poly]]]: """ Compute the multiplication-by-n map on an elliptic curve. :param curve: Curve to compute on. :param n: Scalar. + :param x_only: Whether to skip the my computation. :return: A tuple (mx, my) where each is a tuple (numerator, denominator). """ xs, ys = symbols("x y") @@ -241,6 +242,8 @@ def mult_by_n(curve: EllipticCurve, n: int) -> Tuple[Tuple[Poly, Poly], Tuple[Po # > lc = K(mx_denom.LC()) # > mx = (mx_num.quo(lc), mx_denom.monic()) mx = (mx_num, mx_denom) + if x_only: + return mx, None # The following lines compute # my = ((2*y+a1*x+a3)*mx.derivative(x)/m - a1*mx-a3)/2 diff --git a/pyecsca/sca/re/zvp.py b/pyecsca/sca/re/zvp.py index a92e860..108c9ac 100644 --- a/pyecsca/sca/re/zvp.py +++ b/pyecsca/sca/re/zvp.py @@ -190,8 +190,7 @@ def subs_dlog(poly: Poly, k: int, curve: EllipticCurve): new_gens = set(gens) new_gens.remove(x2) - mx, my = mult_by_n(curve, k) - # TODO: my is unnecessary here so maybe add a function to not compute it (speedup). + mx, _ = mult_by_n(curve, k, x_only=True) u, v = mx[0].subs("x", x1), mx[1].subs("x", x1) # The polynomials are quite dense, hence it makes sense |