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use std::sync::Mutex;
use std::collections::HashMap;
use rand::prelude::*;
use rand::rngs::OsRng;
use x25519_dalek::PublicKey;
use x25519_dalek::StaticSecret;
use x25519_dalek::SharedSecret;
use crate::noise;
use crate::types;
pub struct Output (
Option<types::KeyPair>, // resulting key-pair of successful handshake
Option<Vec<u8>> // message to send
);
pub struct Peer {
// mutable state
m : Mutex<State>,
// constant state
pk : PublicKey, // public key of peer
ss : SharedSecret, // precomputed DH(static, static)
psk : [u8; 32] // psk of peer
}
enum State {
Reset,
InitiationSent,
}
struct Device {
sk : StaticSecret, // static secret key
pk : PublicKey, // static public key
peers : Vec<Peer>, // peer index -> state
pkmap : HashMap<[u8; 32], usize>, // public key -> peer index
ids : Mutex<HashMap<u32, usize>> // receive ids -> peer index
}
/* A mutable reference to the state machine needs to be held,
* during configuration.
*/
impl Device {
/// Initialize a new handshake state machine
///
/// # Arguments
///
/// * `sk` - x25519 scalar representing the local private key
pub fn new(sk : StaticSecret) -> Device {
Device {
pk : PublicKey::from(&sk),
sk : sk,
peers : vec![],
pkmap : HashMap::new(),
ids : Mutex::new(HashMap::new())
}
}
/// Add a new public key to the state machine
/// To remove public keys, you must create a new machine instance
///
/// # Arguments
///
/// * `pk` - The public key to add
///
/// # Returns
///
/// The call might fail if the public key corresponds to the secret key of the machine
pub fn add(&mut self, pk : PublicKey) -> Result<(), ()> {
// check that the pk is not added twice
if let Some(_) = self.pkmap.get(pk.as_bytes()) {
return Err(());
};
// check that the pk is not that of the device
if *self.pk.as_bytes() == *pk.as_bytes() {
return Err(());
}
// map : pk -> new index
self.pkmap.insert(*pk.as_bytes(), self.peers.len());
// map : new index -> peer
self.peers.push(Peer {
m : Mutex::new(State::Reset),
pk : pk,
ss : self.sk.diffie_hellman(&pk),
psk : [0u8; 32]
});
Ok(())
}
/// Add a psk to the peer
///
/// # Arguments
///
/// * `pk` - The public key of the peer
/// * `psk` - The psk to set / unset
///
/// # Returns
///
/// The call might fail if the public key is not found
pub fn psk(&mut self, pk : PublicKey, psk : Option<[u8; 32]>) -> Result<(), ()> {
match self.pkmap.get(pk.as_bytes()) {
Some(&idx) => {
let peer = &mut self.peers[idx];
peer.psk = match psk {
Some(v) => v,
None => [0u8; 32],
};
Ok(())
},
_ => Err(())
}
}
/// Release an id back to the pool
///
/// # Arguments
///
/// * `id` - The (sender) id to release
pub fn release(&self, id : u32) {
self.ids.lock().unwrap().remove(&id);
}
/// Begin a new handshake
///
/// # Arguments
///
/// * `pk` - Public key of peer to initiate handshake for
pub fn begin(&self, pk : PublicKey) -> Result<Vec<u8>, ()> {
match self.pkmap.get(pk.as_bytes()) {
None => Err(()),
Some(&idx) => {
let peer = &self.peers[idx];
let id = self.allocate(idx);
noise::create_initiation(peer, id)
}
}
}
/// Process a handshake message.
///
/// # Arguments
///
/// * `msg` - Byte slice containing the message (untrusted input)
pub fn process(&self, msg : &[u8]) -> Result<Output, ()> {
// inspect type field
match msg.get(0) {
_ => Err(())
}
}
}
impl Device {
// allocate a new index (id), for peer with idx
fn allocate(&self, idx : usize) -> u32 {
let mut rng = OsRng;
let mut table = self.ids.lock().unwrap();
loop {
let id = rng.gen();
if !table.contains_key(&id) {
table.insert(id, idx);
return id;
}
}
}
}
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