[noise] handshake state init helper

quicktap/src/noise/handshake/mod.rs

@@ -1,5 +1,6 @@
 //! `Noise_IKpsk2` handshake, specifically the way WireGuard defines it
 use std::fmt::{Debug, Formatter};
+use rand::rngs::OsRng;
 use tai64::Tai64N;
 use x25519_dalek::{EphemeralSecret, PublicKey, StaticSecret};
 use crate::qcrypto::timestamp;
@@ -32,7 +33,7 @@ pub struct Cookie {
 /// Represents the internal handshake state. This does not really need to be messed with by outside users
 #[allow(missing_docs)]
 #[allow(clippy::module_name_repetitions)]
-pub struct HandshakeState {
+pub struct HandshakeState<'a> {
     pub h: [u8; 32],
     pub ck: [u8; 32],
 
@@ -43,7 +44,7 @@ pub struct HandshakeState {
     pub s_pub_r: PublicKey,
 
     pub e_priv_me: StaticSecret,
-    pub s_priv_me: StaticSecret,
+    pub s_priv_me: &'a StaticSecret,
     pub s_pub_them: PublicKey,
 
     pub i_i: u32,
@@ -53,14 +54,34 @@ pub struct HandshakeState {
 
     pub cookies: Vec<Cookie>
 }
-impl HandshakeState {
+impl<'a> HandshakeState<'a> {
     /// Determines if the state variables of this `HandshakeState` are the same as another
     #[allow(clippy::suspicious_operation_groupings)]
     pub fn is_eq(&self, other: &HandshakeState) -> bool {
         self.h == other.h && self.ck == other.ck && self.e_pub_i == other.e_pub_i && self.s_pub_i == other.s_pub_i && self.s_pub_r == other.s_pub_r && self.i_i == other.i_i && self.i_r == other.i_r
     }
+
+    /// Create a new handshake state representing a brand-new handshake.
+    /// This function initializes the important values with their appropriate initialization vectors, and zeroes out all other values.
+    pub fn new(private_key: &StaticSecret, other_pubkey: PublicKey, pre_shared_key: Option<[u8; 32]>) -> Self {
+        Self {
+            h: [0u8; 32],
+            ck: [0u8; 32],
+            e_pub_i: PublicKey::from([0u8; 32]),
+            e_pub_r: PublicKey::from([0u8; 32]),
+            s_pub_i: PublicKey::from([0u8; 32]),
+            s_pub_r: PublicKey::from([0u8; 32]),
+            e_priv_me: StaticSecret::new(OsRng),
+            s_priv_me: private_key,
+            s_pub_them: other_pubkey,
+            i_i: 0,
+            i_r: 0,
+            q: pre_shared_key.unwrap_or([0u8; 32]),
+            cookies: vec![],
+        }
+    }
 }
-impl Debug for HandshakeState {
+impl<'a> Debug for HandshakeState<'a> {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("HandshakeState")
             .field("h", &self.h)

quicktap/src/noise/mod.rs

@@ -1,4 +1,3 @@
 //! Contains structs and functions for serializing and deserializing different packets in the Noise_IKpsk2 handshake and data frames
-
 pub mod handshake;
 pub mod error;