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ec suite_b: De-duplicate to_mont.

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This commit is contained in:
Brian Smith 2023-12-04 12:04:39 -08:00
parent c89b5c6e28
commit 317a062bf4
4 changed files with 11 additions and 37 deletions
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15
mk/generate_curves.py
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@ -115,7 +115,7 @@ pub static PUBLIC_SCALAR_OPS: PublicScalarOps = PublicScalarOps {
q_minus_n: Elem::from_hex("%(q_minus_n)x"),
// TODO: Use an optimized variable-time implementation.
scalar_inv_to_mont_vartime: p%(bits)s_scalar_inv_to_mont,
scalar_inv_to_mont_vartime: |s| PRIVATE_SCALAR_OPS.scalar_inv_to_mont(s),
};
pub static PRIVATE_SCALAR_OPS: PrivateScalarOps = PrivateScalarOps {
@ -125,7 +125,7 @@ pub static PRIVATE_SCALAR_OPS: PrivateScalarOps = PrivateScalarOps {
scalar_inv_to_mont: p%(bits)s_scalar_inv_to_mont,
};
fn p%(bits)s_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
fn p%(bits)s_scalar_inv_to_mont(a: Scalar<R>) -> Scalar<R> {
// Calculate the modular inverse of scalar |a| using Fermat's Little
// Theorem:
//
@ -166,22 +166,13 @@ fn p%(bits)s_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
binary_op_assign(p%(bits)d_scalar_mul_mont, acc, b)
}
fn to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
static N_RR: Scalar<Unencoded> = Scalar {
limbs: PRIVATE_SCALAR_OPS.oneRR_mod_n.limbs,
m: PhantomData,
encoding: PhantomData,
};
binary_op(p%(bits)s_scalar_mul_mont, a, &N_RR)
}
// Indexes into `d`.
const B_1: usize = 0;
todo!();
const DIGIT_COUNT: usize = todo!();
let mut d = [Scalar::zero(); DIGIT_COUNT];
d[B_1] = to_mont(a);
d[B_1] = a;
let b_10 = sqr(&d[B_1]);
for i in B_11..DIGIT_COUNT {
d[i] = mul(&d[i - 1], &b_10);

3
src/ec/suite_b/ops.rs
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@ -319,7 +319,7 @@ pub struct PrivateScalarOps {
pub scalar_ops: &'static ScalarOps,
oneRR_mod_n: Scalar<RR>, // 1 * R**2 (mod n). TOOD: Use One<RR>.
scalar_inv_to_mont: fn(a: &Scalar) -> Scalar<R>,
scalar_inv_to_mont: fn(a: Scalar<R>) -> Scalar<R>,
}
impl PrivateScalarOps {
@ -330,6 +330,7 @@ impl PrivateScalarOps {
/// Returns the modular inverse of `a` (mod `n`). Panics if `a` is zero.
pub fn scalar_inv_to_mont(&self, a: &Scalar) -> Scalar<R> {
assert!(!self.scalar_ops.common.is_zero(a));
let a = self.to_mont(a);
(self.scalar_inv_to_mont)(a)
}
}

15
src/ec/suite_b/ops/p256.rs
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@ -132,7 +132,7 @@ pub static PUBLIC_SCALAR_OPS: PublicScalarOps = PublicScalarOps {
q_minus_n: Elem::from_hex("4319055358e8617b0c46353d039cdaae"),
// TODO: Use an optimized variable-time implementation.
scalar_inv_to_mont_vartime: p256_scalar_inv_to_mont,
scalar_inv_to_mont_vartime: |s| PRIVATE_SCALAR_OPS.scalar_inv_to_mont(s),
};
#[cfg(any(target_arch = "aarch64", target_arch = "x86_64"))]
@ -165,7 +165,7 @@ pub static PRIVATE_SCALAR_OPS: PrivateScalarOps = PrivateScalarOps {
scalar_inv_to_mont: p256_scalar_inv_to_mont,
};
fn p256_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
fn p256_scalar_inv_to_mont(a: Scalar<R>) -> Scalar<R> {
// Calculate the modular inverse of scalar |a| using Fermat's Little
// Theorem:
//
@ -202,15 +202,6 @@ fn p256_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
binary_op_assign(p256_scalar_mul_mont, acc, b);
}
fn to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
static N_RR: Scalar<Unencoded> = Scalar {
limbs: PRIVATE_SCALAR_OPS.oneRR_mod_n.limbs,
m: PhantomData,
encoding: PhantomData,
};
binary_op(p256_scalar_mul_mont, a, &N_RR)
}
// Indexes into `d`.
const B_1: usize = 0;
const B_10: usize = 1;
@ -224,7 +215,7 @@ fn p256_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
let mut d = [Scalar::zero(); DIGIT_COUNT];
d[B_1] = to_mont(a);
d[B_1] = a;
d[B_10] = sqr(&d[B_1]);
d[B_11] = mul(&d[B_10], &d[B_1]);
d[B_101] = mul(&d[B_10], &d[B_11]);

15
src/ec/suite_b/ops/p384.rs
View File

@ -127,7 +127,7 @@ pub static PUBLIC_SCALAR_OPS: PublicScalarOps = PublicScalarOps {
q_minus_n: Elem::from_hex("389cb27e0bc8d21fa7e5f24cb74f58851313e696333ad68c"),
// TODO: Use an optimized variable-time implementation.
scalar_inv_to_mont_vartime: p384_scalar_inv_to_mont,
scalar_inv_to_mont_vartime: |s| PRIVATE_SCALAR_OPS.scalar_inv_to_mont(s),
};
pub static PRIVATE_SCALAR_OPS: PrivateScalarOps = PrivateScalarOps {
@ -137,7 +137,7 @@ pub static PRIVATE_SCALAR_OPS: PrivateScalarOps = PrivateScalarOps {
scalar_inv_to_mont: p384_scalar_inv_to_mont,
};
fn p384_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
fn p384_scalar_inv_to_mont(a: Scalar<R>) -> Scalar<R> {
// Calculate the modular inverse of scalar |a| using Fermat's Little
// Theorem:
//
@ -179,15 +179,6 @@ fn p384_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
binary_op_assign(p384_scalar_mul_mont, acc, b)
}
fn to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
static N_RR: Scalar<Unencoded> = Scalar {
limbs: PRIVATE_SCALAR_OPS.oneRR_mod_n.limbs,
m: PhantomData,
encoding: PhantomData,
};
binary_op(p384_scalar_mul_mont, a, &N_RR)
}
// Indexes into `d`.
const B_1: usize = 0;
const B_11: usize = 1;
@ -200,7 +191,7 @@ fn p384_scalar_inv_to_mont(a: &Scalar<Unencoded>) -> Scalar<R> {
const DIGIT_COUNT: usize = 8;
let mut d = [Scalar::zero(); DIGIT_COUNT];
d[B_1] = to_mont(a);
d[B_1] = a;
let b_10 = sqr(&d[B_1]);
for i in B_11..DIGIT_COUNT {
d[i] = mul(&d[i - 1], &b_10);