Sam, this was a great article. Have you done anything on Ethereum yet?

Can you elaborate on the last sentence:

"This is called a "Pay-to-Public-Key-Hash" script. However, through Bitcoin script other types of conditions are possible. For example, an output could created that could be spent by anyone that could solve a certain hash or a transaction could be created that anyone could spend."

There's a few different pubkey scripts documented on the Bitcoin wiki: https://en.bitcoin.it/wiki/...

I meant I'm just trying to wrap my head around that sentence.

Can you rephrase it so its more clear?

Ah, right! So the signature script creates a "locking condition" on the output, the condition normally is "this output can be spent by the person with the private key to a certain public key" but, instead of that, you can have other conditions such as "this output can be spent by anyone" or "this output can be spent by anyone who knows what sha256 hashes to '12345'".

Does that make a little more sense?

Perfect. Thanks!!

@ http://gobittest.appspot.co...
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip8JkUM7yP5mxSiidLg

Sam, nice write-up! Almost sent the coins to your donation address, but someone else's unconfirmed transaction appeared just minutes before I finished "fixing" up the code :)

How do you specify fees in your transaction creation example?

Thanks for the kind words!

The fee will be the difference between the amount in the output and how much you specify to spend. Miners take whatever part of the UTXO that you don't specify.

awesome work gaz!

https://checkbitcoinaddress...

Check Bitcoin Address for mentions and abuses.

This is very helpful, thanks. One question: you say "This involves replacing the placeholder signature script with the real signature script and removing the hash_code_type from the transaction as shown below." But if you delete the hash_code_type, how will the next Tx trying to use the output of this Tx know how to recompute the signature to verify? What if you had signed this with a hash_code_type that wasn't SIGHASH_ALL? Thanks in advance for the response.

There's an error in your first diagram - "ecsda".

Thank you for the great writeup - really useful.

So good. Thanks so much for this detailed write-up.

Amazing article! You made me want to start writing my own client!
Also, I think I'm going to open my first Bitcoin account very soon.
Thanks!

great article. thanks

I find this really useful. Thanks!

Brilliant! thanks for writing this and educating people about the Bitcoin protocol

I wrote this article describing what a bitcoin actually is on the network a while ago. Your readers may find it useful: https://wildbunny.co.uk/blo...