Bitcoin double spend question, I have an UTXO, I create a transaction where I spend it and send it to the network, the transaction is waiting for confirmation. Then I create another transaction that is spending it moments later.

Is that second transaction rejected by all nodes because the UTXO is no longer in the mempool?

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Crossposted from https://nostrwitter.onrender.com/

Você colocou a invoice, tem que ser o endereço. O lightiningTipBot gera um pra você fácil no telegram.

Eu uso por lá.

Correct congrats! Coloca um endereço da lightning aí no Nostr pra eu conseguir mandar o zap.

The hash for that starts with a 2 and since you are a bot you are blocked.

PROOF OF WORK CHALLENGE, Bounty: 1000 sats.

This is an educational challenge aimed at begginers please leave it be if you are well

versed in Proof of work, here is the challege:

I'll give you a block represented as a piece of text, and you have to mine it like in Bitcoin.

The first to prove they mined the block takes the reward, what is mining you ask? Hashing the block (in Bitcoin the block header)

over and over again until you get a hash that is low enough to reach the target, the target for this challenge is:

0000000f00000000000000000000000000000000000000000000000000000000

And the algorithm SHA256, just like in Bitcoin. Which means you need to come up with a hash that starts with 7 zeroes.

Then you might ask, but hashing the same text always gives the same hash, how do I make it start with zeroes? Here is the

catch, I'll give you a piece of data inside of the block you can change, it's called the nonce, you can put any number or text

in there, it's not size contrained like in Bitcoin, but you can only change the nonce in the block that means the value of the nonce inside the double quotes,

nothing else, Bitcoin let's you change some other data aswell like the coinbase data.

For this target difficulty you are expected to try a few BILLION times, below is the block and the hash of nonce 0, I generated the hash

in Python but in theory you could use any sha256 implementation, even pen and paper (please don't). Please check that your sha256 also hashes

the block with nonce 0 to this hash or you will never be able to reach a valid solution.

To claim the bounty you need to comment on this note with the nonce that mines the block, the fastest miner takes it all (please don't use ASICS, let the newbs have a shot).

Here is the block:

{"Name":"Pretty cool block","Nonce":"0","Transactions":["OP_RETURN 'taxation is theft'","OP_RETURN 'Imposto é roubo'"]}

Here is the hash of the above block:

298736bab199101b89291aef566017bd1294ab778b2139ae0ef0d222a64caf69

Python code to hash:

block = """{"Name":"Pretty cool block","Nonce":"0","Transactions":["OP_RETURN 'taxation is theft'","OP_RETURN 'Imposto é roubo'"]}"""

print(sha256(block.encode('utf-8')).hexdigest())

Example:

Trying some other nonce:

{"Name":"Pretty cool block","Nonce":"fjrovho443443","Transactions":["OP_RETURN 'taxation is theft'","OP_RETURN 'Imposto é roubo'"]}

That hashes to:

469c2774ddf74a75584f327bbd982bfb436cc6e04cc0ccf400a193a430360ecd

No zeroes at the beggining, better try again with another nonce.

Happy mining!

Heard some really smart people mention utreexo, had no idea what it was, then went to YouTube and of course it's created by

@tdryja and he has a talk on it.

Tadge is my second favorite Bitcoin developer, I wish he was more active on Twitter.

https://youtu.be/edRun-6ubCc

38tão é o Enéias do Bitcoin, não sei até que ponto isso é positivo em relação aos no-coiners.

Did someone say cross-post? I built an open source tool for that.

https://nostrwitter.onrender.com/

Esquartejamento lento em praça pública.

Publicar é possível, e fácil o mais complicado aí seria conseguir essas 'notícias do dia' automaticamente.

Hey guys! Check out this skull too cool for school I found on the internets, don't the laser eyes make you want to stack even more sats?

Gm @fiatjaf

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Crossposted from https://nostrwitter.onrender.com

O mundo financeiro dos bancos pegando fogo e os bitconheiros só no modo "tá vendo, eu avisei."

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Crossposted from https://nostrwitter.onrender.com

Em nada, a autenticação do Twitter é feita diretamente com o Twitter. A aplicação recebe uma autorização pra postar que não é armazenada por isso a necessidade de autorizar no Twitter todas as vezes.

Para o nostr todo o processamento é feito no browser do usuário, não passa nada para o servidor.

Mas don't trust, verify. Todo o código é open source é disponível abaixo:

https://github.com/ODevLibertario

Good night frens! Do I deserve a little zap action for those spicy Nostrwitter updates or what.

Did someone ask for NIP-07 login in Nostrwitter? I Know @diegokolling did. Well, good news! It's live now. Just logout, clear your cache, and refresh the page.

A

"Ah Dev, Nostrwitter is cool and all, but I like posting memes, without images it's of no use to me"

Guess what buddy, Nostrwitter v1.2 is live with image uploads at: nostrwitter.onrender.com

Calma moço, tô arrumando ainda kkkk

Does someone now why when posting an image to Nostr, the image is always displayed in the feed above the text?