frost-client: support multiple sessions (#399)

frost-client/Cargo.toml

@@ -30,4 +30,5 @@ frost-rerandomized = { version = "2.0.0-rc.0", features = ["serde"] }
 reddsa = { git = "https://github.com/ZcashFoundation/reddsa.git", rev = "ed49e9ca0699a6450f6d4a9fe62ff168f5ea1ead", features = ["frost"] }
 rand = "0.8"
 stable-eyre = "0.2"
-itertools = "0.13.0"
+itertools = "0.13.0"
+xeddsa = "1.0.2"

frost-client/src/args.rs

@@ -106,6 +106,21 @@ pub(crate) enum Command {
         #[arg(short, long)]
         group: String,
     },
+    /// Lists the active FROST signing sessions the user is in.
+    Sessions {
+        /// The path to the config file to manage. If not specified, it uses
+        /// $HOME/.local/frost/credentials.toml
+        #[arg(short, long)]
+        config: Option<String>,
+        /// The server URL to use. If `group` is specified and `server_url`
+        /// is not, it will use the server URL associated with `group` if any.
+        #[arg(short, long)]
+        server_url: Option<String>,
+        /// Optional group whose associated server URL will be used, identified
+        /// by the group public key (use `groups` to list).
+        #[arg(short, long)]
+        group: Option<String>,
+    },
     Coordinator {
         /// The path to the config file to manage. If not specified, it uses
         /// $HOME/.local/frost/credentials.toml
@@ -155,5 +170,9 @@ pub(crate) enum Command {
         /// to list)
         #[arg(short, long)]
         group: String,
+        /// The session ID to use (use `sessions` to list). Can be omitted in
+        /// case there is a single active session.
+        #[arg(short = 'S', long)]
+        session: Option<String>,
     },
 }

frost-client/src/config.rs

@@ -98,7 +98,7 @@ impl Group {
         );
         for participant in self.participant.values() {
             let contact = config.contact_by_pubkey(&participant.pubkey)?;
-            s += &format!("\t{} ({})\n", contact.name, hex::encode(contact.pubkey));
+            s += &format!("\t{}\t({})\n", contact.name, hex::encode(contact.pubkey));
         }
         Ok(s)
     }

frost-client/src/main.rs

@@ -6,6 +6,7 @@ pub mod coordinator;
 pub mod group;
 pub mod init;
 pub mod participant;
+pub mod session;
 pub mod trusted_dealer;
 pub mod write_atomic;
 
@@ -27,6 +28,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
         Command::RemoveContact { .. } => contact::remove(&args.command),
         Command::Groups { .. } => group::list(&args.command),
         Command::RemoveGroup { .. } => group::remove(&args.command),
+        Command::Sessions { .. } => session::list(&args.command).await,
         Command::TrustedDealer { .. } => trusted_dealer::trusted_dealer(&args.command),
         Command::Coordinator { .. } => crate::coordinator::run(&args.command).await,
         Command::Participant { .. } => crate::participant::run(&args.command).await,

frost-client/src/participant.rs

@@ -40,6 +40,7 @@ pub(crate) async fn run_for_ciphersuite<C: RandomizedCiphersuite + 'static>(
         config,
         server_url,
         group,
+        session,
     } = (*args).clone()
     else {
         panic!("invalid Command");
@@ -72,7 +73,7 @@ pub(crate) async fn run_for_ciphersuite<C: RandomizedCiphersuite + 'static>(
             .ok_or_eyre("host missing in URL")?
             .to_owned(),
         port: server_url_parsed.port().unwrap_or(2744),
-        session_id: String::new(),
+        session_id: session.unwrap_or_default(),
         comm_privkey: Some(
             config
                 .communication_key

frost-client/src/session.rs

@@ -0,0 +1,131 @@
+use std::error::Error;
+
+use eyre::{eyre, OptionExt as _};
+use rand::thread_rng;
+use xeddsa::{xed25519, Sign as _};
+
+use crate::{args::Command, config::Config};
+
+pub(crate) async fn list(args: &Command) -> Result<(), Box<dyn Error>> {
+    let Command::Sessions {
+        config,
+        group,
+        server_url,
+    } = (*args).clone()
+    else {
+        panic!("invalid Command");
+    };
+
+    let config = Config::read(config)?;
+
+    let server_url = if let Some(server_url) = server_url {
+        server_url
+    } else if let Some(group) = group {
+        let group = config.group.get(&group).ok_or_eyre("Group not found")?;
+        group
+            .server_url
+            .clone()
+            .ok_or_eyre("the group specified does not have an associated server URL")?
+    } else {
+        return Err(eyre!("must specify either server_url or group").into());
+    };
+
+    let comm_privkey = config
+        .communication_key
+        .clone()
+        .ok_or_eyre("user not initialized")?
+        .privkey
+        .clone();
+    let comm_pubkey = config
+        .communication_key
+        .clone()
+        .ok_or_eyre("user not initialized")?
+        .pubkey
+        .clone();
+
+    let client = reqwest::Client::new();
+    let host_port = format!("http://{}", server_url);
+
+    let mut rng = thread_rng();
+
+    let challenge = client
+        .post(format!("{}/challenge", host_port))
+        .json(&server::ChallengeArgs {})
+        .send()
+        .await?
+        .json::<server::ChallengeOutput>()
+        .await?
+        .challenge;
+
+    let privkey = xed25519::PrivateKey::from(
+        &TryInto::<[u8; 32]>::try_into(comm_privkey.clone())
+            .map_err(|_| eyre!("invalid comm_privkey"))?,
+    );
+    let signature: [u8; 64] = privkey.sign(challenge.as_bytes(), &mut rng);
+
+    let access_token = client
+        .post(format!("{}/login", host_port))
+        .json(&server::KeyLoginArgs {
+            uuid: challenge,
+            pubkey: comm_pubkey.clone(),
+            signature: signature.to_vec(),
+        })
+        .send()
+        .await?
+        .json::<server::LoginOutput>()
+        .await?
+        .access_token
+        .to_string();
+
+    // Get session ID from server
+    let r = client
+        .post(format!("{}/list_sessions", host_port))
+        .bearer_auth(&access_token)
+        .send()
+        .await?
+        .json::<server::ListSessionsOutput>()
+        .await?;
+
+    if r.session_ids.is_empty() {
+        eprintln!("No active sessions.");
+    } else {
+        for session_id in r.session_ids {
+            let r = client
+                .post(format!("{}/get_session_info", host_port))
+                .bearer_auth(&access_token)
+                .json(&server::GetSessionInfoArgs { session_id })
+                .send()
+                .await?
+                .json::<server::GetSessionInfoOutput>()
+                .await?;
+            let coordinator = config.contact_by_pubkey(&r.coordinator_pubkey);
+            let participants: Vec<_> = r
+                .pubkeys
+                .iter()
+                .map(|pubkey| config.contact_by_pubkey(pubkey))
+                .collect();
+            eprintln!("Session with ID {}", session_id);
+            eprintln!(
+                "Coordinator: {}",
+                coordinator
+                    .map(|c| c.name)
+                    .unwrap_or("(Unknown contact)".to_string())
+            );
+            eprintln!("Signers: {}", participants.len());
+            for participant in participants {
+                if let Ok(participant) = participant {
+                    eprintln!(
+                        "\t{}\t({})",
+                        participant.name,
+                        hex::encode(participant.pubkey)
+                    );
+                } else {
+                    eprintln!("\t(Unknown contact)");
+                }
+            }
+            eprintln!();
+        }
+    }
+
+    Ok(())
+}

participant/src/comms/http.rs

@@ -232,7 +232,7 @@ where
                     .json::<server::ListSessionsOutput>()
                     .await?;
                 if r.session_ids.len() > 1 {
-                    return Err(eyre!("user has more than one FROST session active, which is still not supported by this tool").into());
+                    return Err(eyre!("user has more than one FROST session active; use `frost-client sessions` to list them and specify the session ID with `-S`").into());
                 } else if r.session_ids.is_empty() {
                     return Err(eyre!("User has no current sessions active. The Coordinator should either specify your username, or manually share the session ID which you can specify with --session_id").into());
                 }