Add blockstack transaction generation support to blockstack.js #382

mikecohen.id · June 6, 2018, 12:18pm

I’m looking to create a provenance record for art work and secure/time stamp a hash of this record in bitcoin with a provably un-spendable output asking the user to pay a minimal fee.

Is there a way to interact with the users wallet to find an unspent output, create a raw transaction with the hash stored in op_return and change address and then ask the user to sign it and broadcast it?

Many thanks, Mike.

aaron · June 13, 2018, 6:14pm

Hi @mikecohen.id –

There’s not a way to do this exactly, but there are ways to broadcast a provenance record from a client application given a user’s private keys.

You could use transactions.makeUpdate:

github.com

blockstack/blockstack.js/blob/master/src/operations/txbuild.js#L446


* @param {String} zonefile - the zonefile data to update (this will be hashed
*    to include in the transaction), the zonefile itself must be published
*    after the UPDATE propagates.
* @param {String} valueHash - if given, this is the hash to store (instead of
*    zonefile).  zonefile will be ignored if this is given.
* @returns {Promise} - a promise which resolves to the hex-encoded transaction.
*    this function *does not* perform the requisite safety checks -- please see
*    the safety module for those.
* @private
*/
function makeUpdate(fullyQualifiedName: string,
                   ownerKeyHex: string,
                   paymentKeyHex: string,
                   zonefile: string,
                   valueHash: string = '') {
 const network = config.network
 if (!valueHash && !zonefile) {
   return Promise.reject(
     new Error('Need zonefile or valueHash arguments'))
 }
 if (valueHash.length === 0) {

Passing the provenance record as the zonefile contents. This would create an UPDATE record in the blockchain, which contains a hash of the zone file contents, and broadcasts the corresponding zone file in the Atlas peer network.