# Blockfrost/Cardano serialisation lib - Issue while signing transaction - signing key **URL:** \ **Category:** Cardano Integration\ **Created:** [9 February 2022 17:28 UTC](https://forum.cardano.org/t/blockfrost-cardano-serialisation-lib-issue-while-signing-transaction-signing-key/95233 "2022-02-09T17:28:55Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![AkshitV](https://avatars.discourse-cdn.com/v4/letter/a/779978/32.png) [@AkshitV](https://forum.cardano.org/u/AkshitV)\ **Post date:** [9 February 2022 17:28 UTC](https://forum.cardano.org/t/blockfrost-cardano-serialisation-lib-issue-while-signing-transaction-signing-key/95233/1 "2022-02-09T17:28:55Z")
Hi fellas, i am following this to create and submit a transaction using this ([https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/index.ts](https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/index.ts)) But as we can see that this is basically only considering the utxos of the address 0. And it uses Address 0’s private key i guess to submit a transaction. However there could be a case where utxos might be in some other address of the same account with same mnemonics. So to use utxos of different addresses, i just looped through all the associated addreses which have utxos and i pushed them here in this utxo array ([https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/index.ts#L45](https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/index.ts#L45)) But as you can see the signing key that they are using is derived and returned over here ([https://github.com/blockfrost/blockfrost-js/blob/fb9a55fee07927f8d7c8b0a5aa9efd2d3daf6c77/examples/simple-transaction/src/helpers/key.ts#L45](https://github.com/blockfrost/blockfrost-js/blob/fb9a55fee07927f8d7c8b0a5aa9efd2d3daf6c77/examples/simple-transaction/src/helpers/key.ts#L45)) And then using this key to sign transaction over here ([https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/helpers/signTransaction.ts](https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/helpers/signTransaction.ts)) So i wanted to know what should i pass as the sign key so that every utxo, which is from any address can be signed. Also what should be its format ? I am getting this error when i use bipPrvKey.to\_raw\_key() as the sign key: transaction submit error ShelleyTxValidationError ShelleyBasedEraAlonzo (ApplyTxError [UtxowFailure (WrappedShelleyEraFailure (MissingVKeyWitnessesUTXOW (WitHashes (fromList [KeyHash “some \_hash\_here”]))))])" Also i might not understand anything apart from blockfrost or cardano serialization library. Open to any kind of help or suggestions . Thanks in advance 🙂 ---
**Author:** ![bakon11](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.cardano.org/bakon11/32/47167_2.png) [@bakon11](https://forum.cardano.org/u/bakon11)\ **Post date:** [12 February 2022 16:12 UTC](https://forum.cardano.org/t/blockfrost-cardano-serialisation-lib-issue-while-signing-transaction-signing-key/95233/2 "2022-02-12T16:12:04Z")
Hey, I was wondering if you’ve made any head way on your issue? I’m facing the same problem and also made an issue on the github here. > > > So I'm just creating a simple TX of sending some ADA from one address to another… and cardano-cli spits out the following error. > > \`Command failed: transaction submit Error: Error while submitting tx: ShelleyTxValidationError ShelleyBasedEraAlonzo (ApplyTxError \[UtxowFailure (WrappedShelleyEraFailure (MissingVKeyWitnessesUTXOW (WitHashes (fromList \[KeyHash "a1c10c4767a63fe4983f1882d74d110652e9e7335d49db55f94e9841"\]))))\]) > \` > > Am I understanding correctly based on this\`MissingVKeyWitnessesUTXOW\`: that I'm not signing the TX correctly? > > Thank you. > > Example of my code: > > \`\`\`typescript > import CardanoWasm = require('@emurgo/cardano-serialization-lib-nodejs') > import { mnemonicToEntropy } from 'bip39'; > import { entropyToRoot } from "../utils/wallet"; > > export const buildTX = async ( key: string, txix: string, txixIndex: number, inputValue: string, outputAddress: string, outputValue: > string, changeAddress: string, txTTL: number ) =\> { > > // instantiate the tx builder with the Cardano protocol parameters - these may change later on > const txBuilder = CardanoWasm.TransactionBuilder.new( > CardanoWasm.TransactionBuilderConfigBuilder.new() > .fee\_algo( CardanoWasm.LinearFee.new(CardanoWasm.BigNum.from\_str('44'),CardanoWasm.BigNum.from\_str('155381'))) > .pool\_deposit(CardanoWasm.BigNum.from\_str('500000000'),) > .key\_deposit( CardanoWasm.BigNum.from\_str('2000000'),) > .coins\_per\_utxo\_word(CardanoWasm.BigNum.from\_str('34482')) > .max\_value\_size(5000) > .max\_tx\_size(16384) > .build() > ); > > // NOTE: The private key here is modified and will not work it is just show as an example > const entropy = await mnemonicToEntropy("fantasy length rug fatal bounce shield dad went out soccer sustain almost female street merit finish raven cost play shove height extra anxiety hint"); > > //Creates Root key from Entropy > const rootKey = await entropyToRoot( entropy ); > // derives a hardened account xprv key > const xprvKey: any = await genAccountKeyPrv(rootKey, purpose, coinType); > > // output address > const shelleyOutputAddress = CardanoWasm.Address.from\_bech32(outputAddress); > // change address > const shelleyChangeAddress = CardanoWasm.Address.from\_bech32(changeAddress); > > txBuilder.add\_key\_input( > xprvKey.to\_public().to\_raw\_key().hash(), > CardanoWasm.TransactionInput.new( > CardanoWasm.TransactionHash.from\_bytes( > Buffer.from(txix, "hex") > ), // tx hash > txixIndex, // index > ), > CardanoWasm.Value.new(CardanoWasm.BigNum.from\_str(inputValue)) > ); > > // output for receiver > txBuilder.add\_output( > CardanoWasm.TransactionOutputBuilder.new() > .with\_address(shelleyOutputAddress) > .next() > .with\_value(CardanoWasm.Value.new(CardanoWasm.BigNum.from\_str(outputValue))) > .build() > ); > > // set the time to live - the absolute slot value before the tx becomes invalid > txBuilder.set\_ttl(txTTL); > > // calculate the min fee required and send any change to an address > txBuilder.add\_change\_if\_needed(shelleyChangeAddress); > > // once the transaction is ready, we build it to get the tx body without witnesses > const txBody = txBuilder.build(); > const txHash = CardanoWasm.hash\_transaction(txBody); > const witnesses = CardanoWasm.TransactionWitnessSet.new(); > > // add keyhash witnesses > const vkeyWitnesses = CardanoWasm.Vkeywitnesses.new(); > const vkeyWitness = CardanoWasm.make\_vkey\_witness(txHash, xprvKey.to\_raw\_key()); > vkeyWitnesses.add(vkeyWitness); > witnesses.set\_vkeys(vkeyWitnesses); > > // create the finalized transaction with witnesses > const transaction = CardanoWasm.Transaction.new( > txBody, > witnesses, > undefined, // transaction metadata > ); > > const txHex = Buffer.from(transaction.to\_bytes()).toString("hex"); > console.log(txHex); > return(txHex); > }; > \`\`\` Thanks. ---
**Author:** ![AkshitV](https://avatars.discourse-cdn.com/v4/letter/a/779978/32.png) [@AkshitV](https://forum.cardano.org/u/AkshitV)\ **Post date:** [16 February 2022 07:59 UTC](https://forum.cardano.org/t/blockfrost-cardano-serialisation-lib-issue-while-signing-transaction-signing-key/95233/3 "2022-02-16T07:59:01Z")
Hi @bakon11 Yes that got resolved with correct signKey. But i am currently facing this issue : were transaction.to\_bytes() defined over here ([blockfrost-js/index.ts at master · blockfrost/blockfrost-js · GitHub](https://github.com/blockfrost/blockfrost-js/blob/master/examples/simple-transaction/src/index.ts#L88)) return an empty array : Uint8Array(0) It sometimes return correct Array when i run from one file, then if i call this from some other file it returns this empty Array. The variable transaction is of class Transaction only (when i log it). Could this be somehow related to some wasm memory buffer issue ?