Introduce secure mode (part 1) (#1808)

Use noise protocol on handshake. Check peer's public key if needed. Also support rekey and replay attack prevention.

E2EE and temporary password will be implemented based on this.

easytier/src/proto/api_instance.proto

@@ -41,6 +41,9 @@ message PeerConnInfo {
   bool is_client = 8;
   string network_name = 9;
   bool is_closed = 10;
+  bytes noise_local_static_pubkey = 11;
+  bytes noise_remote_static_pubkey = 12;
+  peer_rpc.SecureAuthLevel secure_auth_level = 13;
 }
 
 message PeerInfo {

easytier/src/proto/api_manage.proto

@@ -81,6 +81,8 @@ message NetworkConfig {
   optional common.CompressionAlgoPb data_compress_algo = 52;
   optional string encryption_algorithm = 53;
   optional bool disable_tcp_hole_punching = 54;
+
+  common.SecureModeConfig secure_mode = 55;
 }
 
 message PortForwardConfig {

easytier/src/proto/common.proto

@@ -230,3 +230,13 @@ message LimiterConfig {
   optional uint64 fill_duration_ms =
       3; // default 10ms, the period to fill the bucket
 }
+
+message SecureModeConfig {
+  bool enabled = 1; 
+
+  // base64(X25519 private key), used by shared node to present a stable identity
+  optional string local_private_key = 2;
+
+  // base64(X25519 public key), required if local_private_key is set
+  optional string local_public_key = 3;
+}

easytier/src/proto/common.rs

@@ -4,6 +4,7 @@ use std::{
 };
 
 use anyhow::Context;
+use base64::{prelude::BASE64_STANDARD, Engine as _};
 
 use crate::tunnel::packet_def::CompressorAlgo;
 
@@ -360,3 +361,37 @@ impl fmt::Debug for Ipv6Addr {
         write!(f, "{}", std_ipv6_addr)
     }
 }
+
+impl SecureModeConfig {
+    pub fn private_key(&self) -> anyhow::Result<x25519_dalek::StaticSecret> {
+        let local_private_key = self
+            .local_private_key
+            .as_ref()
+            .ok_or_else(|| anyhow::anyhow!("local private key is not set"))?;
+        let k = BASE64_STANDARD
+            .decode(local_private_key)
+            .with_context(|| format!("failed to decode private key: {}", local_private_key))?;
+        // convert vec to 32b array
+        let len = k.len();
+        let k: [u8; 32] = k
+            .try_into()
+            .map_err(|_| anyhow::anyhow!("invalid private key length: {}", len))?;
+        Ok(x25519_dalek::StaticSecret::from(k))
+    }
+
+    pub fn public_key(&self) -> anyhow::Result<x25519_dalek::PublicKey> {
+        let local_public_key = self
+            .local_public_key
+            .as_ref()
+            .ok_or_else(|| anyhow::anyhow!("local public key is not set"))?;
+        let k = BASE64_STANDARD
+            .decode(local_public_key)
+            .with_context(|| format!("failed to decode public key: {}", local_public_key))?;
+        // convert vec to 32b array
+        let len = k.len();
+        let k: [u8; 32] = k
+            .try_into()
+            .map_err(|_| anyhow::anyhow!("invalid public key length: {}", len))?;
+        Ok(x25519_dalek::PublicKey::from(k))
+    }
+}

easytier/src/proto/peer_rpc.proto

@@ -251,10 +251,51 @@ message HandshakeRequest {
   uint32 version = 3;
   repeated string features = 4;
   string network_name = 5;
-  bytes network_secret_digrest = 6;
+  bytes network_secret_digest = 6;
 }
 
 message KcpConnData {
   common.SocketAddr src = 1;
   common.SocketAddr dst = 4;
 }
+
+enum SecureAuthLevel {
+  None = 0;
+  EncryptedUnauthenticated = 1;
+  SharedNodePubkeyVerified = 2;
+  NetworkSecretConfirmed = 3;
+}
+
+enum PeerConnSessionActionPb {
+  Join = 0;
+  Sync = 1;
+  Create = 2;
+}
+
+message PeerConnNoiseMsg1Pb {
+  uint32 version = 1;
+  string a_network_name = 2;
+  optional uint32 a_session_generation = 3;
+  common.UUID a_conn_id = 4;
+  string client_encryption_algorithm = 5;
+}
+
+message PeerConnNoiseMsg2Pb {
+  string b_network_name = 1;
+  uint32 role_hint = 2;
+  PeerConnSessionActionPb action = 3;
+  uint32 b_session_generation = 4;
+  optional bytes root_key_32 = 5;
+  uint32 initial_epoch = 6;
+  common.UUID b_conn_id = 7;
+  common.UUID a_conn_id_echo = 8;
+  optional bytes secret_proof_32 = 9;
+  string server_encryption_algorithm = 10;
+}
+
+message PeerConnNoiseMsg3Pb {
+  common.UUID a_conn_id_echo = 1;
+  common.UUID b_conn_id_echo = 2;
+  optional bytes secret_proof_32 = 3;
+  bytes secret_digest = 4;
+}