How to sign RAW transactions?

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The Venly Wallet-API takes care of the complete blockchain management to execute transactions (signing, submitting, and follow-up).

We advise only using the regular transaction API (POST /transactions/execute) to perform blockchain operations. Only use the below-described functionality if you have a deep understanding how blockchain technology works.

Context

In some cases, you may want to submit transactions yourself to the blockchain. For example, you may want to submit transactions through your own blockchain node when you run your own node.

To be able to do this, you will need to encode the RAW transaction data and sign this data with the respective Venly-wallet. The resulting signature can then be used to submit the transaction to the blockchain.

This page shows examples of retrieving the signature for different chains.

Request Endpoint: reference

POST /api/signatures

Request Body:

The body for the endpoint depends on which chain the transaction is for. First, there is a set of common fields and then there are some custom fields per (type of) chain.

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Note that there is a difference between creating a transaction for a native token transfer or calling a contract:

• For native token transactions, the provided API can be used as described, without providing a data element. No encoded function is needed.
• For calling contracts or doing (ERC-20, ERC-721, or ERC-1155) token transactions, which are basically contract calls as well (safeTransferFrom function), you'll need to construct the (transaction-)data yourself.

There are a number of libraries that allow you to build the encoded transaction data (e.g. web3j for Java, web3py for Python, etc.)

In web3j, building the encoded function looks something like this:

List inputParams = new ArrayList();
List outputParams = new ArrayList();
Function function = new Function("fuctionName", inputParams, outputParams);
String encodedFunction = FunctionEncoder.encode(function)

The encodedFunction is what needs to be passed as data in the Request Body.

Types

• ETHEREUM_TRANSACTION
• BSC_TRANSACTION
• AVAC_TRANSACTION
• MATIC_TRANSACTION
• GOCHAIN_TRANSACTION
• VECHAIN_TRANSACTION
• BITCOIN_TRANSACTION
• LITECOIN_TRANSACTION
• AETERNITY_TRANSACTION
• NEO_NATIVE_TRANSACTION
• NEO_GAS_TRANSACTION
• HEDERA_TRANSACTION

Common Fields

{
  walletId!: string,
  submit!: boolean,
  type!: Type
}

Custom Fields

EVM based chains

This applies to the following types ETHEREUM_TRANSACTION , BSC_TRANSACTION , AVAC_TRANSACTION , MATIC_TRANSACTION and GOCHAIN_TRANSACTION .

{
  walletId!: string,
  submit!: boolean,
  type!: Type,
  
  to!: string,
  value?: number,
  data?: string,
  gas!: number,
  gasPrice!: number,
  nonce!: number
}

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If you want a prediction of the gas/gasPrice and the next nonce, you can submit the request first to POST /signatures/prepare (leaving these fields empty).
This will then return you a gas estimate + the next nonce.

Types of transaction

Vechain Transaction

{
  walletId!: string,
  submit!: boolean,
  type!: VECHAIN_TRANSACTION,
  
  blockRef?: string,
  chainTag?: string,
  expiration?: number,
  gas?: number,
  gasPriceCoef?: number,
  nonce?: string,
  clauses!: [{
    to!: string,
    amount?: number,
    data?: string
  }] 
}

Bitcoin Transaction

 {
  walletId!: string,
  submit!: boolean,
  type!: BITCOIN_TRANSACTION,
  
  to!: string,
  value?: number,
  feePerByte?: number
}

Litecoin Transaction

{
  walletId!: string,
  submit!: boolean,
  type!: LITECOIN_TRANSACTION,
  
  to!: string,
  value?: number,
  feePerKiloByte?: number
}

AEternity Transaction

{
  walletId!: string,
  submit!: boolean,
  type!: AETERNITY_TRANSACTION,
  
  to!: string,
  value?: number,
  data?: string,
  nonce?: number,
  fee?: number,
  ttl?: number
}

Neo native Transaction

{
  walletId!: string,
  submit!: boolean,
  type!: NEO_NATIVE_TRANSACTION,
  
  to!: string,
  value?: number
}

Neo gas Transaction

{
  walletId!: string,
  submit!: boolean,
  type!: NEO_GAS_TRANSACTION,
  
  to!: string,
  value?: number
}

Hedera Transaction

{
  walletId!: string,
  submit!: boolean,
  type!: HEDERA_TRANSACTION,
  
  data?: string
}

Response Body:

{
  type!: 'TRANSACTION_SIGNATURE',
  signedTransaction!: string
}