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transaction

Tooling for offline transaction creation and signing.

jcli transaction

Those familiar with cardano-cli transaction builder will see resemblance in jcli transaction.

There is a couple of commands that can be used to:

  1. prepare a transaction:

    • new create a new empty transaction;
    • add-input
    • add-account
    • add-output
  2. finalize the transaction for signing:
  3. create witnesses and add the witnesses:

    • make-witness
    • add-witness
  4. seal the transaction, ready to send to the blockchain

There are also functions to help decode and display the content information of a transaction:

  • info
  • id to get the Transaction ID of the transaction
  • to-message to get the hexadecimal encoded message, ready to send with cli rest message

Examples

The following example focuses on using an utxo as input, the few differences when transfering from an account will be pointed out when necessary. There is also a script here to send a transaction from a faucet account to a specific address which could be used as a reference.

Let’s use the following utxo as input and transfer 50 lovelaces to the destination address

Input utxo

FieldValue
UTXO’s transaction ID55762218e5737603e6d27d36c8aacf8fcd16406e820361a8ac65c7dc663f6d1c
UTXO’s output index0
associated addressca1q09u0nxmnfg7af8ycuygx57p5xgzmnmgtaeer9xun7hly6mlgt3pjyknplu
associated value100

Destination address

address: ca1qvnr5pvt9e5p009strshxndrsx5etcentslp2rwj6csm8sfk24a2wlqtdj6

Create a staging area

jcli transaction new > tx

Add input

For the input, we need to reference the uxto with the UTXO’s transaction ID and UTXO’S output index fields and we need to specify how much coins are there with the associated value field.

Example - UTXO address as Input

jcli transaction add-input  55762218e5737603e6d27d36c8aacf8fcd16406e820361a8ac65c7dc663f6d1c 0 100 --staging tx

Example - Account address as Input

If the input is an account, the command is slightly different

jcli transaction add-account account_address account_funds --staging tx

Add output

For the output, we need the address we want to transfer to, and the amount.

jcli transaction add-output  ca1qvnr5pvt9e5p009strshxndrsx5etcentslp2rwj6csm8sfk24a2wlqtdj6 50 --staging tx

Add fee and change address

We want to get the change in the same address that we are sending from (the associated address of the utxo). We also specify how to compute the fees. You can leave out the --fee-constant 5 --fee-coefficient 2 part if those are both 0.

jcli transaction finalize  ca1q09u0nxmnfg7af8ycuygx57p5xgzmnmgtaeer9xun7hly6mlgt3pjyknplu --fee-constant 5 --fee-coefficient 2 --staging tx

Now, if you run

jcli transaction info --fee-constant 5 --fee-coefficient 2 --staging tx

You should see something like this

Transaction `0df39a87d3f18a188b40ba8c203f85f37af665df229fb4821e477f6998864273' (finalizing)
  Input:   100
  Output:  89
  Fees:    11
  Balance: 0
 - 55762218e5737603e6d27d36c8aacf8fcd16406e820361a8ac65c7dc663f6d1c:0 100
 + ca1qvnr5pvt9e5p009strshxndrsx5etcentslp2rwj6csm8sfk24a2wlqtdj6 50
 + ca1q09u0nxmnfg7af8ycuygx57p5xgzmnmgtaeer9xun7hly6mlgt3pjyknplu 39

Sign the transaction

Make witness

For signing the transaction, you need the private key associated with the input address (the one that’s in the utxos) and the hash of the genesis block of the network you are connected to.

The genesis’ hash is needed for ensuring that the transaction cannot be re-used in another blockchain and for security concerns on offline transaction signing, as we are signing the transaction for the specific blockchain started by this block0 hash.

The following command takes the private key in the key.prv file and creates a witness in a file named witness in the current directory.

jcli transaction make-witness --genesis-block-hash abcdef987654321... --type utxo txid witness key.prv

Account input

When using an account as input, the command takes account as the type and an additional parameter: --account-spending-counter, that should be increased every time the account is used as input.

e.g.

jcli transaction make-witness --genesis-block-hash abcdef987654321... --type account --account-spending-counter 0 witness key.prv

Add witness

jcli transaction add-witness witness --staging tx

Send the transaction

jcli transaction seal --staging tx
jcli transaction to-message --staging tx > txmsg

Send it using the rest api

jcli rest v0 message post -f txmsg --host http://127.0.0.1:8443/api

Checking if the transaction was accepted

You can check if the transaction was accepted by checking the node logs, for example, if the transaction is accepted

jcli rest v0 message logs -h http://127.0.0.1:8443/api

---
- fragment_id: d6ef0b2148a51ed64531efc17978a527fd2d2584da1e344a35ad12bf5460a7e2
  last_updated_at: "2019-06-11T15:38:17.070162114Z"
  received_at: "2019-06-11T15:37:09.469101162Z"
  received_from: Rest
  status:
    InABlock: "4.707"

Where the InABlock status means that the transaction was accepted in the block with date “4.707”.

The status here could also be:

Pending: if the transaction is received and is pending being added in the blockchain (or rejected).

or

Rejected: with an attached message of the reason the transaction was rejected.