Authentication of PeerIds in authority discovery records (#10317)

* Consolidating test and production code

* Signing/verifying authority discovery records with PeerId

Unsigned records cannot be rejected yet, they just produce
a warning in the log.

* Upgrading to libp2p 0.40

* libp2p::identity and sp_core::crypto Ed25519 are compatible

* Rejecting authority records unsigned by peer id can be configured

* Fixes based on review comments

* No command-line argument needed

* info was still too much spam in the logs

* Added tests for both strict and loose validation

* Fixing based on review comments

* Pierre preferred a signing method

* Ooops, I need to slow down

* Update bin/node/cli/src/service.rs

* Reexport libp2p crypto used in sc-network

* Added proto3 compatibility tests. And import noise.

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/network/src/lib.rs

@@ -273,8 +273,9 @@ pub use protocol::{
 	PeerInfo,
 };
 pub use service::{
-	IfDisconnected, NetworkService, NetworkWorker, NotificationSender, NotificationSenderReady,
-	OutboundFailure, RequestFailure,
+	DecodingError, IfDisconnected, KademliaKey, Keypair, NetworkService, NetworkWorker,
+	NotificationSender, NotificationSenderReady, OutboundFailure, PublicKey, RequestFailure,
+	Signature, SigningError,
 };
 
 pub use sc_peerset::ReputationChange;

substrate/client/network/src/service.rs

@@ -54,7 +54,6 @@ use libp2p::{
 		either::EitherError,
 		upgrade, ConnectedPoint, Executor,
 	},
-	kad::record,
 	multiaddr,
 	ping::Failure as PingFailure,
 	swarm::{
@@ -93,9 +92,19 @@ pub use behaviour::{
 
 mod metrics;
 mod out_events;
+mod signature;
 #[cfg(test)]
 mod tests;
 
+pub use libp2p::{
+	identity::{
+		error::{DecodingError, SigningError},
+		Keypair, PublicKey,
+	},
+	kad::record::Key as KademliaKey,
+};
+pub use signature::*;
+
 /// Substrate network service. Handles network IO and manages connectivity.
 pub struct NetworkService<B: BlockT + 'static, H: ExHashT> {
 	/// Number of peers we're connected to.
@@ -106,6 +115,8 @@ pub struct NetworkService<B: BlockT + 'static, H: ExHashT> {
 	is_major_syncing: Arc<AtomicBool>,
 	/// Local copy of the `PeerId` of the local node.
 	local_peer_id: PeerId,
+	/// The `KeyPair` that defines the `PeerId` of the local node.
+	local_identity: Keypair,
 	/// Bandwidth logging system. Can be queried to know the average bandwidth consumed.
 	bandwidth: Arc<transport::BandwidthSinks>,
 	/// Peerset manager (PSM); manages the reputation of nodes and indicates the network which
@@ -318,7 +329,7 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkWorker<B, H> {
 				};
 
 				transport::build_transport(
-					local_identity,
+					local_identity.clone(),
 					config_mem,
 					params.network_config.yamux_window_size,
 					yamux_maximum_buffer_size,
@@ -406,6 +417,7 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkWorker<B, H> {
 			is_major_syncing: is_major_syncing.clone(),
 			peerset: peerset_handle,
 			local_peer_id,
+			local_identity,
 			to_worker,
 			peers_notifications_sinks: peers_notifications_sinks.clone(),
 			notifications_sizes_metric: metrics
@@ -667,6 +679,14 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkService<B, H> {
 		&self.local_peer_id
 	}
 
+	/// Signs the message with the `KeyPair` that defined the local `PeerId`.
+	pub fn sign_with_local_identity(
+		&self,
+		msg: impl AsRef<[u8]>,
+	) -> Result<Signature, SigningError> {
+		Signature::sign_message(msg.as_ref(), &self.local_identity)
+	}
+
 	/// Set authorized peers.
 	///
 	/// Need a better solution to manage authorized peers, but now just use reserved peers for
@@ -1024,7 +1044,7 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkService<B, H> {
 	///
 	/// This will generate either a `ValueFound` or a `ValueNotFound` event and pass it as an
 	/// item on the [`NetworkWorker`] stream.
-	pub fn get_value(&self, key: &record::Key) {
+	pub fn get_value(&self, key: &KademliaKey) {
 		let _ = self.to_worker.unbounded_send(ServiceToWorkerMsg::GetValue(key.clone()));
 	}
 
@@ -1032,7 +1052,7 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkService<B, H> {
 	///
 	/// This will generate either a `ValuePut` or a `ValuePutFailed` event and pass it as an
 	/// item on the [`NetworkWorker`] stream.
-	pub fn put_value(&self, key: record::Key, value: Vec<u8>) {
+	pub fn put_value(&self, key: KademliaKey, value: Vec<u8>) {
 		let _ = self.to_worker.unbounded_send(ServiceToWorkerMsg::PutValue(key, value));
 	}
 
@@ -1393,8 +1413,8 @@ enum ServiceToWorkerMsg<B: BlockT, H: ExHashT> {
 	RequestJustification(B::Hash, NumberFor<B>),
 	ClearJustificationRequests,
 	AnnounceBlock(B::Hash, Option<Vec<u8>>),
-	GetValue(record::Key),
-	PutValue(record::Key, Vec<u8>),
+	GetValue(KademliaKey),
+	PutValue(KademliaKey, Vec<u8>),
 	AddKnownAddress(PeerId, Multiaddr),
 	SetReservedOnly(bool),
 	AddReserved(PeerId),

substrate/client/network/src/service/signature.rs

@@ -0,0 +1,50 @@
+// This file is part of Substrate.
+//
+// Copyright (C) 2017-2021 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+//
+// If you read this, you are very thorough, congratulations.
+
+use super::*;
+
+/// A result of signing a message with a network identity. Since `PeerId` is potentially a hash of a
+/// `PublicKey`, you need to reveal the `PublicKey` next to the signature, so the verifier can check
+/// if the signature was made by the entity that controls a given `PeerId`.
+pub struct Signature {
+	/// The public key derived from the network identity that signed the message.
+	pub public_key: PublicKey,
+	/// The actual signature made for the message signed.
+	pub bytes: Vec<u8>,
+}
+
+impl Signature {
+	/// Create a signature for a message with a given network identity.
+	pub fn sign_message(
+		message: impl AsRef<[u8]>,
+		keypair: &Keypair,
+	) -> Result<Self, SigningError> {
+		let public_key = keypair.public();
+		let bytes = keypair.sign(message.as_ref())?;
+		Ok(Self { public_key, bytes })
+	}
+
+	/// Verify whether the signature was made for the given message by the entity that controls the
+	/// given `PeerId`.
+	pub fn verify(&self, message: impl AsRef<[u8]>, peer_id: &PeerId) -> bool {
+		*peer_id == self.public_key.to_peer_id() &&
+			self.public_key.verify(message.as_ref(), &self.bytes)
+	}
+}