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fix(MPC deadlock): give each RCOT consumer its own instance #1173

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fix(MPC deadlock): give each RCOT consumer its own instance #1173

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96c6d50
fix: give each RCOT consumer its own instance to avoid preprocess dea…
AdamDawidKrol Jun 30, 2026
2f9849c
fix(mpc-tls): domain-separate per-consumer KOS instances
AdamDawidKrol Jul 24, 2026
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51 changes: 28 additions & 23 deletions crates/tlsn/src/deps/prover.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,45 +54,50 @@ impl ProverMpcDeps {
let mut rng = rand::rng();
let delta = Delta::new(Block::random(&mut rng));

let base_ot_send = co::Sender::default();
let base_ot_recv = co::Receiver::default();
let rcot_send = kos::Sender::new(
kos::SenderConfig::default(),
delta.into_inner(),
base_ot_recv,
);
let rcot_recv = kos::Receiver::new(kos::ReceiverConfig::default(), base_ot_send);
let rcot_recv = ferret::Receiver::new(
ferret::FerretConfig::builder()
.lpn_type(ferret::LpnType::Regular)
.build()
.expect("ferret config is valid"),
Block::random(&mut rng),
rcot_recv,
);

let rcot_send = SharedRCOTSender::new(rcot_send);
let rcot_recv = SharedRCOTReceiver::new(rcot_recv);
// Each RCOT consumer gets its own instance instead of sharing one. A shared
// RCOT only flushes once all its clones reach the flush barrier, but the
// preprocess branches (ke / record_layer / vm) don't all flush together, so a
// shared instance deadlocks. All senders use the same global delta.
let new_send = || {
SharedRCOTSender::new(kos::Sender::new(
kos::SenderConfig::default(),
delta.into_inner(),
co::Receiver::default(),
))
};
let new_recv = |rng: &mut rand::rngs::ThreadRng| {
let rcot_recv =
kos::Receiver::new(kos::ReceiverConfig::default(), co::Sender::default());
let rcot_recv = ferret::Receiver::new(
ferret::FerretConfig::builder()
.lpn_type(ferret::LpnType::Regular)
.build()
.expect("ferret config is valid"),
Block::random(rng),
rcot_recv,
);
SharedRCOTReceiver::new(rcot_recv)
};

let mpc = cfg_select! {
tlsn_insecure => { mpz_ideal_vm::IdealVm::new() }
_ => {
ProverMpc::new(DerandCOTSender::new(rcot_send.clone()), rng.random(), delta)
ProverMpc::new(DerandCOTSender::new(new_send()), rng.random(), delta)
}
};

let zk = cfg_select! {
tlsn_insecure => { mpz_ideal_vm::IdealVm::new() }
_ => { ProverZk::new(Default::default(), rcot_recv.clone()) }
_ => { ProverZk::new(Default::default(), new_recv(&mut rng)) }
};

let vm = Arc::new(Mutex::new(Deap::new(tlsn_deap::Role::Leader, mpc, zk)));
let mpc_tls = MpcTlsLeader::new(
build_mpc_tls_config(config),
ctx,
vm.clone(),
(rcot_send.clone(), rcot_send.clone(), rcot_send),
rcot_recv,
(new_send(), new_send(), new_send()),
new_recv(&mut rng),
);

Self {
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52 changes: 30 additions & 22 deletions crates/tlsn/src/deps/verifier.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,43 +54,51 @@ impl VerifierMpcDeps {
let mut rng = rand::rng();

let delta = Delta::random(&mut rng);
let base_ot_send = co::Sender::default();
let base_ot_recv = co::Receiver::default();
let rcot_send = kos::Sender::new(
kos::SenderConfig::default(),
delta.into_inner(),
base_ot_recv,
);
let rcot_send = ferret::Sender::new(
ferret::FerretConfig::builder()
.lpn_type(ferret::LpnType::Regular)
.build()
.expect("ferret config is valid"),
Block::random(&mut rng),
rcot_send,
);
let rcot_recv = kos::Receiver::new(kos::ReceiverConfig::default(), base_ot_send);

let rcot_send = SharedRCOTSender::new(rcot_send);
let rcot_recv = SharedRCOTReceiver::new(rcot_recv);
// Each RCOT consumer gets its own instance instead of sharing one. A shared
// RCOT only flushes once all its clones reach the flush barrier, but the
// preprocess branches don't all flush together, so it deadlocks. All senders
// use the same global delta.
let new_send = |rng: &mut rand::rngs::ThreadRng| {
let rcot_send = kos::Sender::new(
kos::SenderConfig::default(),
delta.into_inner(),
co::Receiver::default(),
);
let rcot_send = ferret::Sender::new(
ferret::FerretConfig::builder()
.lpn_type(ferret::LpnType::Regular)
.build()
.expect("ferret config is valid"),
Block::random(rng),
rcot_send,
);
SharedRCOTSender::new(rcot_send)
};
let new_recv = || {
SharedRCOTReceiver::new(kos::Receiver::new(
kos::ReceiverConfig::default(),
co::Sender::default(),
))
};

let mpc = cfg_select! {
tlsn_insecure => { mpz_ideal_vm::IdealVm::new() }
_ => { VerifierMpc::new(DerandCOTReceiver::new(rcot_recv.clone())) }
_ => { VerifierMpc::new(DerandCOTReceiver::new(new_recv())) }
};

let zk = cfg_select! {
tlsn_insecure => { mpz_ideal_vm::IdealVm::new() }
_ => { VerifierZk::new(Default::default(), delta, rcot_send.clone()) }
_ => { VerifierZk::new(Default::default(), delta, new_send(&mut rng)) }
};

let vm = Arc::new(Mutex::new(Deap::new(tlsn_deap::Role::Follower, mpc, zk)));
let mpc_tls = MpcTlsFollower::new(
build_mpc_tls_config(config),
ctx,
vm.clone(),
rcot_send,
(rcot_recv.clone(), rcot_recv.clone(), rcot_recv),
new_send(&mut rng),
(new_recv(), new_recv(), new_recv()),
);

Self {
Expand Down