Can Nami wallet provide the TransactionWitnessSet for minting a native asset?

Question

I'm trying to mint a native asset reusing the keys that Nami already uses. This is to make a minting service that is connected to a specific wallet, and that wallet is always able to mint more tokens if they want to.

However, it doesn't seem like Nami is providing all the signatures that I need. When submitting the transaction I get the following error:

transaction submit error ShelleyTxValidationError ShelleyBasedEraAlonzo (ApplyTxError [UtxowFailure (WrappedShelleyEraFailure (MissingScriptWitnessesUTXOW (fromList [ScriptHash \"9f84ae8b52e374a0cd09e7ec10854309f8dd7b1f5caf69dd658ed6c5\"]))),UtxowFailure (WrappedShelleyEraFailure (UtxoFailure (UtxosFailure (CollectErrors [NoRedeemer (Minting (PolicyID {policyID = ScriptHash \"9f84ae8b52e374a0cd09e7ec10854309f8dd7b1f5caf69dd658ed6c5\"})),NoWitness (ScriptHash \"9f84ae8b52e374a0cd09e7ec10854309f8dd7b1f5caf69dd658ed6c5\")]))))])

I seem to be missing the witness for the native asset script. Is there any way of making Nami sign this or is it impossible? Note that I'm already using the signTx(...) endpoint so it seems to be signing the entire transaction just not what is required by the minting script.

Code:

async function mint(mintData: MintData, wasm: any, walletConnector: WalletConnector){
  const userAddress: Address = wasm.Address.from_bytes(
    Buffer.from(mintData.address, "hex")
  )
  
  const p = await initTx() 

  const txBuilder: TransactionBuilder = wasm.TransactionBuilder.new(
    wasm.TransactionBuilderConfigBuilder.new()
      .fee_algo(wasm.LinearFee.new(wasm.BigNum.from_str(p.linearFee.minFeeA),
                                  wasm.BigNum.from_str(p.linearFee.minFeeB)))
      .pool_deposit(wasm.BigNum.from_str(p.poolDeposit))
      .key_deposit(wasm.BigNum.from_str(p.keyDeposit))
      .coins_per_utxo_word(wasm.BigNum.from_str(p.coinsPerUtxoWord))
      .max_value_size(p.maxValSize)
      .max_tx_size(p.maxTxSize)
      .build()
  );
  
  const invalidHereafter=10

  if (p.slot === null){
    return
  }

  const ttl = p.slot+invalidHereafter
  const timelockExpiry = wasm.TimelockExpiry.new(ttl)
  const timeLockedPolicyScript = wasm.NativeScript.new_timelock_expiry(timelockExpiry)
  const policyScripts = wasm.NativeScripts.new()
  policyScripts.add(timeLockedPolicyScript)
  const scriptHash = wasm.ScriptHash.from_bytes(timeLockedPolicyScript.hash().to_bytes())
  const policyID = bytesToString(timeLockedPolicyScript.hash().to_bytes())

  //const assetName = Buffer.from(mintData.tokenName, 'hex')
  txBuilder.add_mint_asset_and_output_min_required_coin(
    timeLockedPolicyScript, 
    wasm.AssetName.new(mintData.tokenName), 
    wasm.Int.new_i32(mintData.amount),
    userAddress,
    );
  

  const valueFilter: Value = wasm.Value.new(wasm.BigNum.from_str("5000000")) 
  //Add inputs
  const utxos: TransactionUnspentOutputs = wasm.TransactionUnspentOutputs.new();
  (await walletConnector.getUtxos(Buffer.from(valueFilter.to_bytes()).toString('hex')))
                .forEach(rawUTXO => {
                  const utxo: TransactionUnspentOutput = wasm.TransactionUnspentOutput.from_bytes(Buffer.from(rawUTXO, "hex"))
                  utxos.add(utxo)
                })

  
  txBuilder.add_inputs_from(utxos, 0)

  txBuilder.add_change_if_needed(userAddress)
  
  const toBeSignedTx: Transaction = txBuilder.build_tx();
  const rawToBeSignedTx: string = Buffer.from(toBeSignedTx.to_bytes()).toString('hex')

  const rawWitnesses: string = await walletConnector.signTx(rawToBeSignedTx)
  const witnessSet = wasm.TransactionWitnessSet.from_bytes(
    Buffer.from(rawWitnesses, "hex")
  )
  const witnessSets: TransactionWitnessSets = wasm.TransactionWitnessSets.new()
  witnessSets.add(witnessSet)

  const submitTx: Transaction = 
    wasm.Transaction.new(
      toBeSignedTx.body(),
      witnessSet
    )
  const rawSubmitTx: string = Buffer.from(submitTx.to_bytes()).toString('hex')
  walletConnector.submitTx(rawSubmitTx) // <- Error occurs when submitting

}

Answer 1

This error indicates you have all the witnesses you need for the transaction except the minting script and the policy key witness for minting.

You should be able to add a witnessSet to the transaction containing the missing policy script and policy key witness(es) before submitting.

Answer 2

Instead of using a time-locked script, I required the user to include their wallet key as a witness.

Solution:

export async function mint(mintData: MintData, wasm: any, walletConnector: WalletConnector){
    const userAddress: Address = mintData.address.to_address()
    const netId: NetworkID = await walletConnector.getNetworkId()
    const p = initTxStatic(netId) 
  
    const txBuilder: TransactionBuilder = wasm.TransactionBuilder.new(
      wasm.TransactionBuilderConfigBuilder.new()
        .fee_algo(wasm.LinearFee.new(wasm.BigNum.from_str(p.linearFee.minFeeA),
                                    wasm.BigNum.from_str(p.linearFee.minFeeB)))
        .pool_deposit(wasm.BigNum.from_str(p.poolDeposit))
        .key_deposit(wasm.BigNum.from_str(p.keyDeposit))
        .coins_per_utxo_word(wasm.BigNum.from_str(p.coinsPerUtxoWord))
        .max_value_size(p.maxValSize)
        .max_tx_size(p.maxTxSize)
        .build()
    );
    
    const baseAddress: BaseAddress = wasm.BaseAddress.from_address(userAddress)
    const scriptPubKey = wasm.ScriptPubkey.new(baseAddress.payment_cred().to_keyhash())
    const pubKeyScript = wasm.NativeScript.new_script_pubkey(scriptPubKey)
    const policyScripts = wasm.NativeScripts.new()
    policyScripts.add(pubKeyScript)
  
    const hexString = Util.hexEncode(mintData.assetName)
    const assetName: Uint8Array = Uint8Array.from(Buffer.from(hexString, 'hex'));
    txBuilder.add_mint_asset_and_output_min_required_coin(
      pubKeyScript, 
      wasm.AssetName.new(assetName), 
      wasm.Int.new_i32(mintData.amount),
      userAddress,
      );
    
  
    const valueFilter: Value = wasm.Value.new(wasm.BigNum.from_str("5000000")) 
    //Add inputs
    const utxos: TransactionUnspentOutputs = wasm.TransactionUnspentOutputs.new();
    const outputs: TransactionUnspentOutput[]  = (await walletConnector.getUtxos(valueFilter))
    outputs.forEach(utxo => utxos.add(utxo))
  
    
    txBuilder.add_inputs_from(utxos, 0)
  
    txBuilder.add_change_if_needed(userAddress)
    
    const toBeSignedTx: Transaction = txBuilder.build_tx();
  
    const witnessSet: TransactionWitnessSet = await walletConnector.signTx(toBeSignedTx)
  
    witnessSet.set_native_scripts(policyScripts)
  
    const submitTx: Transaction = 
      wasm.Transaction.new(
        toBeSignedTx.body(),
        witnessSet,
        undefined
      )
    await walletConnector.submitTx(submitTx)
  
  }