Adds a signmessage rpc command to the PrivaAPI

teos/proto/teos/v2/tower_services.proto

@@ -6,6 +6,7 @@ import "user.proto";
 import "common/teos/v2/appointment.proto";
 import "common/teos/v2/user.proto";
 import "google/protobuf/empty.proto";
+import "google/protobuf/wrappers.proto";
 
 message NetworkAddress {
   // Tower public API endpoint.
@@ -46,5 +47,6 @@ service PrivateTowerServices {
   rpc get_tower_info(google.protobuf.Empty) returns (GetTowerInfoResponse) {}
   rpc get_users(google.protobuf.Empty) returns (GetUsersResponse) {}
   rpc get_user(GetUserRequest) returns (GetUserResponse) {}
+  rpc sign_message(google.protobuf.StringValue) returns (google.protobuf.StringValue) {}
   rpc stop(google.protobuf.Empty) returns (google.protobuf.Empty) {}
 }

teos/src/api/internal.rs

@@ -395,6 +395,13 @@ impl PrivateTowerServices for Arc<InternalAPI> {
         }
     }
 
+    /// Signs a message using the tower's signing key
+    async fn sign_message(&self, request: Request<String>) -> Result<Response<String>, Status> {
+        Ok(Response::new(
+            self.watcher.sign_message(&request.into_inner()),
+        ))
+    }
+
     /// Stop endpoint. Stops the tower daemon. Part of the private API.
     async fn stop(&self, request: Request<()>) -> Result<Response<()>, Status> {
         self.shutdown_trigger.trigger();

teos/src/cli.rs

@@ -112,6 +112,10 @@ async fn main() {
                 Err(e) => println!("{e}"),
             };
         }
+        Command::SignMessage(m) => {
+            let sig = client.sign_message(Request::new(m.message)).await;
+            println!("{}", sig.unwrap().into_inner());
+        }
         Command::Stop => {
             println!("Shutting down tower");
             client.stop(Request::new(())).await.unwrap();

teos/src/cli_config.rs

@@ -16,6 +16,8 @@ pub enum Command {
     GetUsers,
     /// Gets information about a specific user
     GetUser(GetUserData),
+    /// Signs a message using the tower's secret key
+    SignMessage(MessageToSign),
     /// Requests a graceful shutdown of the tower
     Stop,
 }
@@ -33,6 +35,12 @@ pub struct GetAppointmentsData {
     pub locator: String,
 }
 
+#[derive(Debug, StructOpt, Clone)]
+pub struct MessageToSign {
+    /// The locator of the appointments (16-byte hexadecimal string).
+    pub message: String,
+}
+
 /// Holds all the command line options and commands.
 #[derive(StructOpt, Debug)]
 #[structopt(rename_all = "lowercase")]

teos/src/watcher.rs

@@ -650,6 +650,11 @@ impl Watcher {
 
         Ok((subscription_info, locators))
     }
+
+    /// Signs a message using the tower's signing key
+    pub(crate) fn sign_message(&self, message: &str) -> String {
+        cryptography::sign(message.as_bytes(), &self.signing_key).unwrap()
+    }
 }
 
 /// Listen implementation by the [Watcher]. Handles monitoring and reorgs.