efficient_sm2/key/
public.rs

1// Copyright 2020 Yao Pengfei.
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
15use crate::elem::{scalar_to_unencoded, Scalar, R};
16use crate::err::KeyRejectedError;
17use crate::jacobian::exchange::big_endian_affine_from_jacobian;
18use crate::limb::{Limb, LIMB_BYTES, LIMB_LENGTH};
19use crate::norop::parse_big_endian;
20use crate::sm2p256::{base_point_mul, to_jacobi, to_mont};
21
22#[derive(Copy, Clone, Eq, PartialEq)]
23pub struct PublicKey {
24    bytes: [u8; PUBLIC_KEY_LEN],
25}
26
27impl PublicKey {
28    pub fn new(x: &[u8], y: &[u8]) -> Self {
29        let mut public = PublicKey {
30            bytes: [0; PUBLIC_KEY_LEN],
31        };
32        public.bytes[0] = 4;
33        public.bytes[1..1 + LIMB_LENGTH * LIMB_BYTES].copy_from_slice(x);
34        public.bytes[1 + LIMB_LENGTH * LIMB_BYTES..].copy_from_slice(y);
35
36        public
37    }
38
39    pub fn from_slice(slice: &[u8]) -> Self {
40        let mut bytes = [0; PUBLIC_KEY_LEN];
41        bytes[0] = 4;
42        bytes[1..].copy_from_slice(slice);
43        PublicKey { bytes }
44    }
45
46    pub fn bytes_less_safe(&self) -> &[u8] {
47        &self.bytes
48    }
49
50    pub fn to_point(&self) -> [Limb; LIMB_LENGTH * 3] {
51        let mut x = [0; LIMB_LENGTH];
52        parse_big_endian(&mut x, &self.bytes[1..LIMB_LENGTH * LIMB_BYTES + 1]).unwrap();
53        let x_aff = to_mont(&x);
54
55        let mut y = [0; LIMB_LENGTH];
56        parse_big_endian(&mut y, &self.bytes[LIMB_LENGTH * LIMB_BYTES + 1..]).unwrap();
57        let y_aff = to_mont(&y);
58
59        to_jacobi(&x_aff, &y_aff)
60    }
61
62    pub fn public_from_private(d: &Scalar<R>) -> Result<PublicKey, KeyRejectedError> {
63        let du = scalar_to_unencoded(d);
64        let pk_point = base_point_mul(&du.limbs);
65        let mut x = [0; LIMB_LENGTH * LIMB_BYTES];
66        let mut y = [0; LIMB_LENGTH * LIMB_BYTES];
67
68        big_endian_affine_from_jacobian(&mut x, &mut y, &pk_point)?;
69
70        Ok(PublicKey::new(&x, &y))
71    }
72}
73
74pub const PUBLIC_KEY_LEN: usize = 1 + (2 * LIMB_LENGTH * LIMB_BYTES);
efficient_sm2/key/public.rs

efficient_sm2/key/
public.rs
