I am attempting to sign and submit a simple "always succeeds" transaction body built by the CLI and signed with nami wallet.

cardano-cli transaction build-raw \ --alonzo-era \ --fee 200000 \ --tx-in {NAMI_ADDRESS_UTXO} \ --tx-out {SCRIPT_ADDRESS}+1800000 \ --tx-out {NAMI_ADDRESS}+998000000 \ --invalid-hereafter 50000000 \ --protocol-params-file protocol.json \ --out-file tx-script.draft

Signing this file with an initial key in the CLI, I then sign it with nami using const witnessSet = await window.cardano.signTx(transaction, true);

Generating the following hex CBOR: a10081825820863d383db3cc7494604d02d3bf214706a18a178ce50eb1f04ad3ef45f50815735840da3ef50001e801bb9580ea361cff86fedef6aab41ebf835dbd246afae02a8b380cbfef0bb1c1ad299b57837dcc04d22a8fc81d713989160513fb14020b7ca203

This hex is sent to the back-end where I do some transformations to get the set in the form of [0, [vkey witnesses]].

let bufferWitness = Buffer.from(witnessSet, "hex");
let witnessDecoded = await cbor.decodeFirst(bufferWitness);

const newWitness = [0]; // Array format accepted by the CLI
newWitness.push(witnessDecoded.get(0)[0]); // vkey witness generated by Nami
console.log('Result:', cbor.encode(newWitness).toString("hex"));

This generates the following hex CBOR: 8200825820863d383db3cc7494604d02d3bf214706a18a178ce50eb1f04ad3ef45f50815735840da3ef50001e801bb9580ea361cff86fedef6aab41ebf835dbd246afae02a8b380cbfef0bb1c1ad299b57837dcc04d22a8fc81d713989160513fb14020b7ca203

Decoded as: [0, [h'863D383DB3CC7494604D02D3BF214706A18A178CE50EB1F04AD3EF45F5081573', h'DA3EF50001E801BB9580EA361CFF86FEDEF6AAB41EBF835DBD246AFAE02A8B380CBFEF0BB1C1AD299B57837DCC04D22A8FC81D713989160513FB14020B7CA203']]

When I use cardano-cli assemble to generate the final transaction and submit, I get this error:

ShelleyTxValidationError ShelleyBasedEraAlonzo (ApplyTxError [UtxowFailure (WrappedShelleyEraFailure (InvalidWitnessesUTXOW [VKey (VerKeyEd25519DSIGN "863d383db3cc7494604d02d3bf214706a18a178ce50eb1f04ad3ef45f5081573")]))])

Which I do not understand as the tx body is not altered by the time it is sent to Nami, only signed with a dummy key but I'm assuming that should not affect the witness generated?

Any help would be appreciated, thanks.

3 Answers 3


I also struggled getting this to work via the cli. I went with a solution using the Java cardano-client-lib on the backend to create the base tx, and the cardano-serialization-lib browser package in the browser to add a sig.

here's the relevant browser code (selectively copy-pasted from my project, YMMV)

import * as CardanoSerdes from '@emurgo/cardano-serialization-lib-browser'
const Buffer = require('buffer/').Buffer

// helpers
function toHex(bytes) { return Buffer.from(bytes).toString("hex") }
function fromHex(str) { return Buffer.from(str, "hex") }

const txCborHex = "YOUR BASE TX CBOR HEX HERE"

const namiAddr = "nami wallet addr here"

// parse the base tx into the serialization lib model
const transaction = CardanoSerdes.Transaction.from_bytes(Buffer.from(txCborHex, "hex"))
const transactionWitnessSet = transaction.witness_set()
const transactionBody = transaction.body()

// get a handle on the PubKeyHash for the wallet
const walletAddress = CardanoSerdes.Address.from_bech32(namiAddr)
const baseAddress = CardanoSerdes.BaseAddress.from_address(walletAddress);
const baseAddrBytes = baseAddress.payment_cred().to_keyhash().to_bytes()
const pkh = CardanoSerdes.Ed25519KeyHash.from_bytes(baseAddrBytes)

// Add the pkh as a required signer
const requiredSigners = CardanoSerdes.Ed25519KeyHashes.new();

// draft a new tx for the user to sign
let toSign = CardanoSerdes.Transaction.new(transactionBody, transactionWitnessSet);

// get the user to sign the base tx in the browser via nami
let txVkeyWitnesses = await cardano.signTx(
txVkeyWitnesses = CardanoSerdes.TransactionWitnessSet.from_bytes(

// add the sig to the base tx witness set

// compose a new tx
const readyToSubmit = CardanoSerdes.Transaction.new(transactionBody, transactionWitnessSet);

// convert to cbor hex.  you can submit this in the browser with cardano.submitTx() or using cli on the backend
const finalTx = toHex(readyToSubmit.to_bytes())

the npm deps in use are:

    "@emurgo/cardano-serialization-lib-browser": "^9.1.2",
    "buffer": "^6.0.3",

java dep

  • This turned out to be a very useful answer for integrating a multi-sig pattern with Nami wallet. Thanks for the detailed answer and code.
    – spirois
    Mar 8, 2022 at 14:22

I made a post on this, maybe this can help you. Basically you'd need to first sign transaction with cli, load transaction to cardano-serialization-lib, clear vkeys from witness-set, sign transaction on the frontend and add vkeys from signature witness-set.

Here's a link to my blogpost: https://srdjanstankovic.com/2021/12/24/how-to-sign-and-submit-cardano-cli-transaction-using-nami-wallet.html


The problem is that cardano-serialisazion-lib reorders the transaction and that makes the original witness invalid, https://github.com/Emurgo/cardano-serialization-lib/issues/311

My solution was

  • create tx with cardano-cli
  • deserialize with cardano-serialisazion-lib
  • serialize with cardano-serialisazion-lib
  • sign with cli

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