Add HTLC support to BOLT 3 commitment transaction

smite-ir/src/generators/funding_created.rs

@@ -20,6 +20,7 @@ impl Generator for FundingCreatedGenerator {
     fn generate(&self, builder: &mut ProgramBuilder, rng: &mut impl Rng) {
         // Funding and commitment transaction keys and parameters.
         let opener_funding_privkey = builder.pick_variable(VariableType::PrivateKey, rng);
+        let opener_htlc_basepoint_privkey = builder.pick_variable(VariableType::PrivateKey, rng);
         let opener_funding_pubkey =
             builder.append(Operation::DerivePoint, &[opener_funding_privkey]);
         let acceptor_funding_pubkey = builder.pick_variable(VariableType::Point, rng);
@@ -44,6 +45,7 @@ impl Generator for FundingCreatedGenerator {
             &[
                 funding_transaction,
                 opener_funding_privkey,
+                opener_htlc_basepoint_privkey,
                 temporary_channel_id,
             ],
         );

smite-ir/src/generators/funding_flow.rs

@@ -27,7 +27,8 @@ impl Generator for FundingFlowGenerator {
         let revocation_basepoint = builder.generate_fresh(VariableType::Point, rng);
         let payment_basepoint = builder.generate_fresh(VariableType::Point, rng);
         let delayed_payment_basepoint = builder.generate_fresh(VariableType::Point, rng);
-        let htlc_basepoint = builder.generate_fresh(VariableType::Point, rng);
+        let htlc_basepoint_privkey = builder.generate_fresh(VariableType::PrivateKey, rng);
+        let htlc_basepoint = builder.append(Operation::DerivePoint, &[htlc_basepoint_privkey]);
         let first_per_commitment_point = builder.generate_fresh(VariableType::Point, rng);
 
         // Channel parameters.
@@ -100,7 +101,12 @@ impl Generator for FundingFlowGenerator {
         // Build and send funding_created.
         let sent_funding_created = builder.append(
             Operation::SendFundingCreated,
-            &[funding_transaction, funding_privkey, temporary_channel_id],
+            &[
+                funding_transaction,
+                funding_privkey,
+                htlc_basepoint_privkey,
+                temporary_channel_id,
+            ],
         );
 
         // Receive funding_signed.

smite-ir/src/operation.rs

@@ -184,10 +184,11 @@ pub enum Operation {
     /// Build and send a `funding_created` message (BOLT 2, type 34).
     /// Produces a `SentFundingCreated` variable.
     ///
-    /// Inputs (3):
+    /// Inputs (4):
     ///   0: `funding_transaction` (`FundingTransaction`)
     ///   1: `opener_funding_privkey` (`PrivateKey`)
-    ///   2: `temporary_channel_id` (`ChannelId`)
+    ///   2: `opener_htlc_basepoint_privkey` (`PrivateKey`)
+    ///   3: `temporary_channel_id` (`ChannelId`)
     SendFundingCreated,
     /// Build and send a `channel_ready` message (BOLT 2, type 36).
     ///
@@ -797,6 +798,7 @@ impl Operation {
             Self::SendFundingCreated => vec![
                 VariableType::FundingTransaction, // funding_transaction
                 VariableType::PrivateKey,         // opener_funding_privkey
+                VariableType::PrivateKey,         // opener_htlc_basepoint_privkey
                 VariableType::ChannelId,          // temporary_channel_id
             ],
             Self::SendChannelReady { .. } => vec![

smite-ir/src/tests.rs

@@ -650,7 +650,7 @@ fn postcard_roundtrip() {
             },
             Instruction {
                 operation: Operation::SendFundingCreated,
-                inputs: vec![11, 0, 3],
+                inputs: vec![11, 0, 8, 3],
             },
         ],
     };
@@ -800,19 +800,23 @@ fn displays_send_funding_created_recv_funding_signed_program() {
             inputs: vec![1, 1, 2, 3],
         },
         // funding_created parameters.
+        Instruction {
+            operation: Operation::LoadPrivateKey(key(2)),
+            inputs: vec![],
+        },
         Instruction {
             operation: Operation::LoadChannelId([0xbb; 32]),
             inputs: vec![],
         },
         // Build and send funding_created.
         Instruction {
             operation: Operation::SendFundingCreated,
-            inputs: vec![4, 0, 5],
+            inputs: vec![4, 0, 5, 6],
         },
         // receive funding_signed.
         Instruction {
             operation: Operation::RecvFundingSigned,
-            inputs: vec![6],
+            inputs: vec![7],
         },
     ];
 
@@ -829,9 +833,10 @@ fn displays_send_funding_created_recv_funding_signed_program() {
         "v2 = LoadAmount(10000000)".into(),
         "v3 = LoadFeeratePerKw(15000)".into(),
         "v4 = CreateFundingTransaction(v1, v1, v2, v3)".into(),
-        format!("v5 = LoadChannelId(0x{b32})"),
-        "v6 = SendFundingCreated(v4, v0, v5)".into(),
-        "v7 = RecvFundingSigned(v6)".into(),
+        format!("v5 = LoadPrivateKey(0x{z31}02)"),
+        format!("v6 = LoadChannelId(0x{b32})"),
+        "v7 = SendFundingCreated(v4, v0, v5, v6)".into(),
+        "v8 = RecvFundingSigned(v7)".into(),
     ];
 
     assert_eq!(lines.len(), expected.len(), "line count mismatch");

smite-scenarios/src/executor.rs

@@ -858,7 +858,7 @@ fn build_open_channel(variables: &[Option<Variable>], inputs: &[usize]) -> OpenC
     }
 }
 
-/// Builds a `funding_created` message from 3 input variables.
+/// Builds a `funding_created` message from 4 input variables.
 ///
 /// Channel parameters are read from the negotiated `open_channel` and
 /// `accept_channel` messages recorded in `negotiations`, ensuring the
@@ -876,7 +876,8 @@ fn build_funding_created(
 ) -> Result<FundingCreated, ExecuteError> {
     let funding_tx = resolve_funding_transaction(variables, inputs[0]);
     let opener_funding_privkey_bytes = resolve_private_key(variables, inputs[1]);
-    let temporary_channel_id = resolve_channel_id(variables, inputs[2]);
+    let opener_htlc_basepoint_privkey_bytes = resolve_private_key(variables, inputs[2]);
+    let temporary_channel_id = resolve_channel_id(variables, inputs[3]);
 
     let funding_outpoint = OutPoint {
         txid: funding_tx.tx.compute_txid(),
@@ -913,11 +914,16 @@ fn build_funding_created(
     let secp = Secp256k1::new();
     let opener_funding_pubkey = PublicKey::from_secret_key(&secp, &opener_funding_privkey);
 
+    let opener_htlc_basepoint_privkey =
+        SecretKey::from_slice(&opener_htlc_basepoint_privkey_bytes).expect("valid private key");
+    let opener_htlc_basepoint = PublicKey::from_secret_key(&secp, &opener_htlc_basepoint_privkey);
+
     let opener = ChannelPartyConfig {
         funding_pubkey: opener_funding_pubkey,
         payment_basepoint: open_channel.payment_basepoint,
         revocation_basepoint: open_channel.revocation_basepoint,
         delayed_payment_basepoint: open_channel.delayed_payment_basepoint,
+        htlc_basepoint: opener_htlc_basepoint,
         dust_limit_satoshis: open_channel.dust_limit_satoshis,
         to_self_delay: open_channel.to_self_delay,
     };
@@ -926,6 +932,7 @@ fn build_funding_created(
         payment_basepoint: accept_channel.payment_basepoint,
         revocation_basepoint: accept_channel.revocation_basepoint,
         delayed_payment_basepoint: accept_channel.delayed_payment_basepoint,
+        htlc_basepoint: accept_channel.htlc_basepoint,
         dust_limit_satoshis: accept_channel.dust_limit_satoshis,
         to_self_delay: accept_channel.to_self_delay,
     };
@@ -947,8 +954,10 @@ fn build_funding_created(
     let holder = HolderIdentity {
         side: Side::Opener,
         funding_privkey: opener_funding_privkey,
+        htlc_basepoint_privkey: opener_htlc_basepoint_privkey,
     };
-    let signature = config.sign_counterparty_commitment(&state, &holder);
+    let (signature, htlc_signature) = config.sign_counterparty_commitment(&state, &holder);
+    assert!(htlc_signature.is_empty()); // There are no HTLCs in the initial commitment transaction.
 
     let channel_id = ChannelId::v1_from_funding_outpoint(config.funding_outpoint);
 
@@ -1334,7 +1343,7 @@ fn verify_funding_signed(
 
     state
         .config
-        .verify_counterparty_signature(&state.commitment, &state.holder, &fs.signature)
+        .verify_counterparty_signature(&state.commitment, &state.holder, &fs.signature, &[])
         .then_some(())
         .ok_or(Violation::InvalidCounterpartySignature(fs.channel_id))
 }
@@ -3336,19 +3345,28 @@ mod tests {
     }
 
     fn send_funding_created_and_recv_funding_signed_instructions() -> Vec<Instruction> {
+        let opener_htlc_basepoint_privkey =
+            SecretKey::from_str("1111111111111111111111111111111111111111111111111111111111111111")
+                .unwrap()
+                .secret_bytes();
+
         let mut instrs = create_and_broadcast_tx_instructions();
         instrs.extend(vec![
+            Instruction {
+                operation: Operation::LoadPrivateKey(opener_htlc_basepoint_privkey),
+                inputs: vec![],
+            },
             Instruction {
                 operation: Operation::LoadChannelId([0xbb; 32]),
                 inputs: vec![],
             },
             Instruction {
                 operation: Operation::SendFundingCreated,
-                inputs: vec![6, 0, 8],
+                inputs: vec![6, 0, 8, 9],
             },
             Instruction {
                 operation: Operation::RecvFundingSigned,
-                inputs: vec![9],
+                inputs: vec![10],
             },
         ]);
         instrs
@@ -3414,12 +3432,17 @@ mod tests {
                 "1552dfba4f6cf29a62a0af13c8d6981d36d0ef8d61ba10fb0fe90da7634d7e13",
             )
             .unwrap(),
+            htlc_basepoint_privkey: SecretKey::from_str(
+                "4444444444444444444444444444444444444444444444444444444444444444",
+            )
+            .unwrap(),
         };
 
         assert!(state.config.verify_counterparty_signature(
             &state.commitment,
             &holder,
-            &fc.signature
+            &fc.signature,
+            &[]
         ));
 
         let pending = executor
@@ -3668,13 +3691,13 @@ mod tests {
                 operation: Operation::SendChannelReady {
                     include_alias: false,
                 },
-                inputs: vec![10, 1, 11],
+                inputs: vec![11, 1, 12],
             },
             Instruction {
                 operation: Operation::SendChannelReady {
                     include_alias: true,
                 },
-                inputs: vec![10, 3, 11],
+                inputs: vec![11, 3, 12],
             },
         ]);
 
@@ -4004,7 +4027,7 @@ mod tests {
             },
             Instruction {
                 operation: Operation::SendFundingCreated,
-                inputs: vec![6, 0, 9],
+                inputs: vec![6, 0, 2, 9],
             },
             Instruction {
                 operation: Operation::RecvFundingSigned,