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matthieu/gist:d78bd39a6709c5be3dcd

Created March 7, 2015 22:43
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Sending op_return transactions with BlockCypher
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gistfile1.html
<!DOCTYPE html>
<html lang="en">
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<div class="container">
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<div class="col-md-12">
<form role="form" class="form-inline">
<div class="form-group">
<input type="text" class="box form-control input-lg" maxlength="40" width="40" style="width: 300px;" placeholder="Type something good and short..."/>
<button type="button" class="send btn btn-primary btn-lg" id="browser-websocket">Send it over!</button>
</div>
</form>
<div class="log" style="font-size: 24px; padding-top: 30px; min-height: 300px;"></div>
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<script>
var bytesToHex = Bitcoin.convert.bytesToHex;
var hexToBytes = Bitcoin.convert.hexToBytes;
var mula = {
private : "1af97b1f428ac89b7d35323ea7a68aba8cad178a04eddbbf591f65671bae48a2",
public : "03bb318b00de944086fad67ab78a832eb1bf26916053ecd3b14a3f48f9fbe0821f",
address : "mtWg6ccLiZWw2Et7E5UqmHsYgrAi5wqiov"
}
function hexToString(hexstr) { return Bitcoin.convert.bytesToString(Bitcoin.convert.hexToBytes(hexstr)); };
function sign(data, address) {
var key = Bitcoin.ECKey.fromHex(address.private);
data.pubkeys = [];
data.signatures = data.tosign.map(function(tosign) {
data.pubkeys.push(address.public);
return bytesToHex(key.sign(hexToBytes(tosign)));
});
return data;
}
function sendNullData(str) {
var newtx = {
"inputs": [{"addresses": [mula.address]}],
"outputs": [{addresses: [str], value: 1, script_type: "null-data"}]
};
$.post("http://api.blockcypher.com/v1/btc/test3/txs/new", JSON.stringify(newtx), function(tx) {
var signedtx = sign(tx, mula);
$.post("http://api.blockcypher.com/v1/btc/test3/txs/send", JSON.stringify(signedtx), function(senttx) {
console.log("Sent", senttx.tx.hash);
});
});
}
$(function() {
$(".send").click(function() { sendNullData($(".box").val()); $(".box").val(''); })
var ws = new WebSocket("ws://socket.blockcypher.com/v1/btc/test3");
setInterval(function() {ws.send(JSON.stringify({event: 'ping'}))}, 5000)
ws.onmessage = function(evt) {
var tx = JSON.parse(evt.data);
if (tx.hash) {
$('.log').prepend("<div>"+tx.received.substring(11, 19)+" | "+tx.hash.substring(0, 8)+
"... &gt; " + hexToString(tx.outputs[0].script.substring(2)) + "</div>");
}
}
ws.onopen = function(event) {
ws.send(JSON.stringify({event: "unconfirmed-tx", script: "null-data"}));
}
});
</script>
</body>
</html>
@tanmay-joshi-tfs
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Hi matthieu, /txs/new returns "Error building transaction: Address mystring is of unknown size." when I try the above code. Has there been a change in the blockcypher APIs request format since you wrote this? I went through the documentation, but it doesn't has clear examples for OP_return transactions..

@matthieu
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Author

Nothing should have changed with that address, I'd guess it's more likely related to a decoding issue when using bitcoin-js. What version are you using, the one linked with this script?

@tanmay-joshi-tfs
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tanmay-joshi-tfs commented Aug 11, 2020 •
edited
Loading

I fetched it from https://cdnjs.cloudflare.com/ajax/libs/bitcoinjs-lib/0.2.0-1/bitcoinjs-min.js. But http://api.blockcypher.com/v1/btc/test3/txs/new is returning 400 at line 135 itself, before decoding.
Screenshot 2020-08-11 at 11 07 53 PM

@tanmay-joshi-tfs
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Here's the payload:
{"inputs":[{"addresses":["mnXp7HZ7aH4PjT21Q2BvWzeCdigXo1CQGX"]}], "outputs":[{"addresses":["Mystring"],"value":1,"script_type":"null-data"}]}:

@gregnomis
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Bump
I keep getting this error when attaching a 32 byte hash to a OP_RETURN:
Error creating transaction skeleton: {
errors: [ { error: 'Error no data to embed for OP_RETURN output 1.' } ],

my txskeleton:
Creating transaction skeleton with requestBody: {
"inputs": [
{
"addresses": [
"bc1qu05e8nvpy5f9pyyxs9c76drvksfqsy6gztf70u"
]
}
],
"outputs": [
{
"addresses": [
"bc1quul9kxpd63mghcgj6h5gc7g5c2zqmnmzex94ml"
],
"value": 700
},
{
"script_type": "null-data",
"data": "84e4111fc915e6465cc024512b590a93e7fd99bdc4b50f15e45b7cae3c7588ea",
"value": 0
}
],
"token": "8a2fe74g171c45379ad7bc3b655510ef"
}

any ideas?

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