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use std::ops;
use super::Secp256k1;
use key::{SecretKey, PublicKey};
use ffi;
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
#[repr(C)]
pub struct SharedSecret(ffi::SharedSecret);
impl SharedSecret {
#[inline]
pub fn new(secp: &Secp256k1, point: &PublicKey, scalar: &SecretKey) -> SharedSecret {
unsafe {
let mut ss = ffi::SharedSecret::blank();
let res = ffi::secp256k1_ecdh(secp.ctx, &mut ss, point.as_ptr(), scalar.as_ptr());
debug_assert_eq!(res, 1);
SharedSecret(ss)
}
}
#[inline]
pub fn new_raw(secp: &Secp256k1, point: &PublicKey, scalar: &SecretKey) -> SharedSecret {
unsafe {
let mut ss = ffi::SharedSecret::blank();
let res = ffi::secp256k1_ecdh_raw(secp.ctx, &mut ss, point.as_ptr(), scalar.as_ptr());
debug_assert_eq!(res, 1);
SharedSecret(ss)
}
}
#[inline]
pub fn as_ptr(&self) -> *const ffi::SharedSecret {
&self.0 as *const _
}
}
impl From<ffi::SharedSecret> for SharedSecret {
#[inline]
fn from(ss: ffi::SharedSecret) -> SharedSecret {
SharedSecret(ss)
}
}
impl ops::Index<usize> for SharedSecret {
type Output = u8;
#[inline]
fn index(&self, index: usize) -> &u8 {
&self.0[index]
}
}
impl ops::Index<ops::Range<usize>> for SharedSecret {
type Output = [u8];
#[inline]
fn index(&self, index: ops::Range<usize>) -> &[u8] {
&self.0[index]
}
}
impl ops::Index<ops::RangeFrom<usize>> for SharedSecret {
type Output = [u8];
#[inline]
fn index(&self, index: ops::RangeFrom<usize>) -> &[u8] {
&self.0[index.start..]
}
}
impl ops::Index<ops::RangeFull> for SharedSecret {
type Output = [u8];
#[inline]
fn index(&self, _: ops::RangeFull) -> &[u8] {
&self.0[..]
}
}
#[cfg(test)]
mod tests {
use rand::thread_rng;
use super::SharedSecret;
use super::super::Secp256k1;
#[test]
fn ecdh() {
let s = Secp256k1::with_caps(::ContextFlag::SignOnly);
let (sk1, pk1) = s.generate_keypair(&mut thread_rng()).unwrap();
let (sk2, pk2) = s.generate_keypair(&mut thread_rng()).unwrap();
let sec1 = SharedSecret::new(&s, &pk1, &sk2);
let sec2 = SharedSecret::new(&s, &pk2, &sk1);
let sec_odd = SharedSecret::new(&s, &pk1, &sk1);
assert_eq!(sec1, sec2);
assert!(sec_odd != sec2);
}
}
#[cfg(all(test, feature = "unstable"))]
mod benches {
use rand::thread_rng;
use test::{Bencher, black_box};
use super::SharedSecret;
use super::super::Secp256k1;
#[bench]
pub fn bench_ecdh(bh: &mut Bencher) {
let s = Secp256k1::with_caps(::ContextFlag::SignOnly);
let (sk, pk) = s.generate_keypair(&mut thread_rng()).unwrap();
let s = Secp256k1::new();
bh.iter( || {
let res = SharedSecret::new(&s, &pk, &sk);
black_box(res);
});
}
}