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bigint: Split
BoxedLimbs into its own submodule.
`git diff HEAD^1:src/arithmetic/bigint.rs src/arithmetic/bigint/boxed_limbs.rs`
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| // Copyright 2015-2023 Brian Smith. | ||
| // | ||
| // Permission to use, copy, modify, and/or distribute this software for any | ||
| // purpose with or without fee is hereby granted, provided that the above | ||
| // copyright notice and this permission notice appear in all copies. | ||
| // | ||
| // THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES | ||
| // WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | ||
| // MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY | ||
| // SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | ||
| // WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION | ||
| // OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN | ||
| // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | ||
|
|
||
| use super::{Modulus, Width}; | ||
| use crate::{ | ||
| error, | ||
| limb::{self, Limb, LimbMask, LIMB_BYTES}, | ||
| }; | ||
| use alloc::{borrow::ToOwned, boxed::Box, vec}; | ||
| use core::{ | ||
| marker::PhantomData, | ||
| ops::{Deref, DerefMut}, | ||
| }; | ||
|
|
||
| /// All `BoxedLimbs<M>` are stored in the same number of limbs. | ||
| pub(super) struct BoxedLimbs<M> { | ||
| limbs: Box<[Limb]>, | ||
|
|
||
| /// The modulus *m* that determines the size of `limbx`. | ||
| m: PhantomData<M>, | ||
| } | ||
|
|
||
| impl<M> Deref for BoxedLimbs<M> { | ||
| type Target = [Limb]; | ||
| #[inline] | ||
| fn deref(&self) -> &Self::Target { | ||
| &self.limbs | ||
| } | ||
| } | ||
|
|
||
| impl<M> DerefMut for BoxedLimbs<M> { | ||
| #[inline] | ||
| fn deref_mut(&mut self) -> &mut Self::Target { | ||
| &mut self.limbs | ||
| } | ||
| } | ||
|
|
||
| // TODO: `derive(Clone)` after https://github.com/rust-lang/rust/issues/26925 | ||
| // is resolved or restrict `M: Clone`. | ||
| impl<M> Clone for BoxedLimbs<M> { | ||
| fn clone(&self) -> Self { | ||
| Self { | ||
| limbs: self.limbs.clone(), | ||
| m: self.m, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl<M> BoxedLimbs<M> { | ||
| // The caller must ensure that `limbs.len()` is the same width as the | ||
| // modulus. | ||
| pub(super) fn new_unchecked(limbs: Box<[Limb]>) -> Self { | ||
| Self { | ||
| limbs, | ||
| m: PhantomData, | ||
| } | ||
| } | ||
|
|
||
| pub(super) fn positive_minimal_width_from_be_bytes( | ||
| input: untrusted::Input, | ||
| ) -> Result<Self, error::KeyRejected> { | ||
| // Reject leading zeros. Also reject the value zero ([0]) because zero | ||
| // isn't positive. | ||
| if untrusted::Reader::new(input).peek(0) { | ||
| return Err(error::KeyRejected::invalid_encoding()); | ||
| } | ||
| let num_limbs = (input.len() + LIMB_BYTES - 1) / LIMB_BYTES; | ||
| let mut r = Self::zero(Width { | ||
| num_limbs, | ||
| m: PhantomData, | ||
| }); | ||
| limb::parse_big_endian_and_pad_consttime(input, &mut r) | ||
| .map_err(|error::Unspecified| error::KeyRejected::unexpected_error())?; | ||
| Ok(r) | ||
| } | ||
|
|
||
| pub(super) fn minimal_width_from_unpadded(limbs: &[Limb]) -> Self { | ||
| debug_assert_ne!(limbs.last(), Some(&0)); | ||
| Self { | ||
| limbs: limbs.to_owned().into_boxed_slice(), | ||
| m: PhantomData, | ||
| } | ||
| } | ||
|
|
||
| pub(super) fn from_be_bytes_padded_less_than( | ||
| input: untrusted::Input, | ||
| m: &Modulus<M>, | ||
| ) -> Result<Self, error::Unspecified> { | ||
| let mut r = Self::zero(m.width()); | ||
| limb::parse_big_endian_and_pad_consttime(input, &mut r)?; | ||
| if limb::limbs_less_than_limbs_consttime(&r, m.limbs()) != LimbMask::True { | ||
| return Err(error::Unspecified); | ||
| } | ||
| Ok(r) | ||
| } | ||
|
|
||
| #[inline] | ||
| pub(super) fn is_zero(&self) -> bool { | ||
| limb::limbs_are_zero_constant_time(&self.limbs) == LimbMask::True | ||
| } | ||
|
|
||
| pub(super) fn zero(width: Width<M>) -> Self { | ||
| Self { | ||
| limbs: vec![0; width.num_limbs].into_boxed_slice(), | ||
| m: PhantomData, | ||
| } | ||
| } | ||
|
|
||
| pub(super) fn width(&self) -> Width<M> { | ||
| Width { | ||
| num_limbs: self.limbs.len(), | ||
| m: PhantomData, | ||
| } | ||
| } | ||
|
|
||
| pub(super) fn into_limbs(self) -> Box<[Limb]> { | ||
| self.limbs | ||
| } | ||
| } |
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