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use zeroize::Zeroize;
use super::crypto_core::{crypto_scalarmult, crypto_scalarmult_base};
use super::crypto_generichash::{
crypto_generichash, crypto_generichash_final, crypto_generichash_init,
crypto_generichash_update,
};
use crate::constants::{
CRYPTO_KX_PUBLICKEYBYTES, CRYPTO_KX_SECRETKEYBYTES, CRYPTO_KX_SEEDBYTES,
CRYPTO_KX_SESSIONKEYBYTES, CRYPTO_SCALARMULT_BYTES,
};
use crate::error::Error;
use crate::types::*;
pub type PublicKey = [u8; CRYPTO_KX_PUBLICKEYBYTES];
pub type SecretKey = [u8; CRYPTO_KX_SECRETKEYBYTES];
pub type SessionKey = [u8; CRYPTO_KX_SESSIONKEYBYTES];
pub fn crypto_kx_seed_keypair(
seed: &[u8; CRYPTO_KX_SEEDBYTES],
) -> Result<(PublicKey, SecretKey), Error> {
let mut sk = SecretKey::default();
let mut pk = PublicKey::default();
crypto_generichash(&mut sk, seed, None)?;
crypto_scalarmult_base(&mut pk, &sk);
Ok((pk, sk))
}
pub fn crypto_kx_keypair() -> (PublicKey, SecretKey) {
let sk = SecretKey::gen();
let mut pk = PublicKey::default();
crypto_scalarmult_base(&mut pk, &sk);
(pk, sk)
}
fn crypto_kx(
x1: &mut SessionKey,
x2: &mut SessionKey,
client_pk: &PublicKey,
server_pk: &PublicKey,
mut shared_secret: [u8; CRYPTO_SCALARMULT_BYTES],
) -> Result<(), Error> {
let mut keys = [0u8; 2 * CRYPTO_KX_SESSIONKEYBYTES];
let mut hasher = crypto_generichash_init(None, 2 * CRYPTO_KX_SESSIONKEYBYTES)?;
crypto_generichash_update(&mut hasher, &shared_secret);
shared_secret.zeroize();
crypto_generichash_update(&mut hasher, client_pk);
crypto_generichash_update(&mut hasher, server_pk);
crypto_generichash_final(hasher, &mut keys)?;
x1.copy_from_slice(&keys[..CRYPTO_KX_SESSIONKEYBYTES]);
x2.copy_from_slice(&keys[CRYPTO_KX_SESSIONKEYBYTES..]);
keys.zeroize();
Ok(())
}
pub fn crypto_kx_client_session_keys(
rx: &mut SessionKey,
tx: &mut SessionKey,
client_pk: &PublicKey,
client_sk: &SecretKey,
server_pk: &PublicKey,
) -> Result<(), Error> {
let mut shared_secret = [0u8; CRYPTO_SCALARMULT_BYTES];
crypto_scalarmult(&mut shared_secret, client_sk, server_pk);
crypto_kx(rx, tx, client_pk, server_pk, shared_secret)
}
pub fn crypto_kx_server_session_keys(
rx: &mut SessionKey,
tx: &mut SessionKey,
server_pk: &PublicKey,
server_sk: &SecretKey,
client_pk: &PublicKey,
) -> Result<(), Error> {
let mut shared_secret = [0u8; CRYPTO_SCALARMULT_BYTES];
crypto_scalarmult(&mut shared_secret, server_sk, client_pk);
crypto_kx(tx, rx, client_pk, server_pk, shared_secret)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_kx() {
for _ in 0..20 {
let (client_pk, client_sk) = crypto_kx_keypair();
let (server_pk, server_sk) = crypto_kx_keypair();
let (mut crx, mut ctx, mut srx, mut stx) = (
SessionKey::default(),
SessionKey::default(),
SessionKey::default(),
SessionKey::default(),
);
crypto_kx_client_session_keys(&mut crx, &mut ctx, &client_pk, &client_sk, &server_pk)
.expect("client kx failed");
crypto_kx_server_session_keys(&mut srx, &mut stx, &server_pk, &server_sk, &client_pk)
.expect("server kx failed");
assert_eq!(crx, stx);
assert_eq!(ctx, srx);
use sodiumoxide::crypto::kx;
let client_pk = kx::PublicKey::from_slice(&client_pk).expect("client pk failed");
let client_sk = kx::SecretKey::from_slice(&client_sk).expect("client sk failed");
let server_pk = kx::PublicKey::from_slice(&server_pk).expect("server pk failed");
let server_sk = kx::SecretKey::from_slice(&server_sk).expect("server sk failed");
let (rx1, tx1) = match kx::client_session_keys(&client_pk, &client_sk, &server_pk) {
Ok((rx, tx)) => (rx, tx),
Err(()) => panic!("bad server signature"),
};
let (rx2, tx2) = match kx::server_session_keys(&server_pk, &server_sk, &client_pk) {
Ok((rx, tx)) => (rx, tx),
Err(()) => panic!("bad client signature"),
};
assert_eq!(rx1.as_ref(), crx);
assert_eq!(rx2.as_ref(), srx);
assert_eq!(tx1.as_ref(), ctx);
assert_eq!(tx2.as_ref(), stx);
}
}
}