ring/arithmetic/
montgomery.rs

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1// Copyright 2017 Brian Smith.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15// Indicates that the element is not encoded; there is no *R* factor
16// that needs to be canceled out.
17#[derive(Copy, Clone)]
18pub enum Unencoded {}
19
20// Indicates that the element is encoded; the value has one *R*
21// factor that needs to be canceled out.
22#[derive(Copy, Clone)]
23pub enum R {}
24
25// Indicates the element is encoded twice; the value has two *R*
26// factors that need to be canceled out.
27#[derive(Copy, Clone)]
28pub enum RR {}
29
30// Indicates the element is inversely encoded; the value has one
31// 1/*R* factor that needs to be canceled out.
32#[derive(Copy, Clone)]
33pub enum RInverse {}
34
35pub trait Encoding {}
36
37impl Encoding for RR {}
38impl Encoding for R {}
39impl Encoding for Unencoded {}
40impl Encoding for RInverse {}
41
42/// The encoding of the result of a reduction.
43pub trait ReductionEncoding {
44    type Output: Encoding;
45}
46
47impl ReductionEncoding for RR {
48    type Output = R;
49}
50impl ReductionEncoding for R {
51    type Output = Unencoded;
52}
53impl ReductionEncoding for Unencoded {
54    type Output = RInverse;
55}
56
57/// The encoding of the result of a multiplication.
58pub trait ProductEncoding {
59    type Output: Encoding;
60}
61
62impl<E: ReductionEncoding> ProductEncoding for (Unencoded, E) {
63    type Output = E::Output;
64}
65
66impl<E: Encoding> ProductEncoding for (R, E) {
67    type Output = E;
68}
69
70impl<E: ReductionEncoding> ProductEncoding for (RInverse, E)
71where
72    E::Output: ReductionEncoding,
73{
74    type Output = <<E as ReductionEncoding>::Output as ReductionEncoding>::Output;
75}
76
77// XXX: Rust doesn't allow overlapping impls,
78// TODO (if/when Rust allows it):
79// impl<E1, E2: ReductionEncoding> ProductEncoding for
80//         (E1, E2) {
81//     type Output = <(E2, E1) as ProductEncoding>::Output;
82// }
83impl ProductEncoding for (RR, Unencoded) {
84    type Output = <(Unencoded, RR) as ProductEncoding>::Output;
85}
86impl ProductEncoding for (RR, RInverse) {
87    type Output = <(RInverse, RR) as ProductEncoding>::Output;
88}
ring/arithmetic/montgomery.rs

ring/arithmetic/
montgomery.rs
