Method generate_taproot_leaf_2_script

bridge/src/connectors/connector_b.rs:74–126

(&self)

    }

    fn generate_taproot_leaf_2_script(&self) -> ScriptBuf {
        const TWO_WEEKS_IN_SECONDS: u32 = 60 * 60 * 24 * 14;
        let superblock_hash_public_key =
            &self.commitment_public_keys[&CommitmentMessageId::SuperblockHash];
        let start_time_public_key = &self.commitment_public_keys[&CommitmentMessageId::StartTime];

        // Expected witness:
        // n-of-n Schnorr signature
        // SB' (byte stream)
        // Committed start time (Winternitz sig)
        // Committed SB hash (Winternitz sig)

        script! {
            // Verify superblock hash commitment sig
            { winternitz_message_checksig(superblock_hash_public_key) }
            // Convert committed SB hash to number and push it to altstack
            { sb_hash_from_nibbles() }
            { H256::toaltstack() }          // Stack: SB' sig(start_time) | Altstack: SB.hash

            // Verify start time commitment sig
            { winternitz_message_checksig(start_time_public_key) }
            // Convert committed start time to number and push it to altstack
            { digits_to_number::<{ START_TIME_MESSAGE_LENGTH * 2 }, { LOG_D as usize }>() }
            OP_TOALTSTACK                   // Stack: SB' | Altstack: SB.hash start_time

            extract_superblock_ts_from_header
                                            // Stack: SB' SB'.time | Altstack: SB.hash start_time

            // SB'.time > start_time
            OP_FROMALTSTACK                 // Stack: SB' SB'.time start_time | Altstack: SB.hash
            OP_2DUP                         // Stack: SB' SB'.time start_time SB'.time start_time | Altstack: SB.hash
            OP_GREATERTHAN OP_VERIFY        // Stack: SB' SB'.time start_time | Altstack: SB.hash

            // SB'.time < start_time + 2 weeks
            { TWO_WEEKS_IN_SECONDS } OP_ADD // Stack: SB' SB'.time (start_time + 2 weeks) | Altstack: SB.hash
            OP_LESSTHAN OP_VERIFY           // Stack: SB' | Altstack: SB.hash

            // Calculate SB' hash
            { sha256(SUPERBLOCK_MESSAGE_LENGTH) }
            { sha256_32bytes() }
            { sb_hash_from_bytes() }        // Stack: SB'.hash | Altstack: SB.hash

            // SB'.weight > SB.weight
            // We're comparing hashes as numbers (smaller number = bigger weight),
            // so we need to evaluate (SB'.hash < SB.hash).
            { H256::fromaltstack() }        // Stack: SB'.hash SB.hash
            { H256::lessthan(1, 0) } OP_VERIFY

            { self.n_of_n_taproot_public_key }
            OP_CHECKSIG
        }
        .compile()
    }

    fn generate_taproot_leaf_2_tx_in(&self, input: &Input) -> TxIn {
        generate_default_tx_in(input)