The Coinbase etymology and Satoshi's message on the Bitcoin blockchain

To most people, Coinbase just means the crypto exchange. However, it took its name from a special field in Bitcoin blocks called "coinbase".

The fun part is that this field can contain arbitrary data, and this has been used by Satoshi himself, digital graffiti artists and nerds looking for a fun way to do marriage proposals. And also for a few bad things, but let's not go there.

Let's decode Satoshi's first message manually to see how this works. I'll use online tools exclusively, so everyone can follow along.

While the presence of this message is very well known, the punchline at the end of this post is less widely known.

I thought it would be interesting for people to learn the rough process of finding such nuggets. By scanning the blockchain with a script, you can automate all this to look for interesting content. With a bit of Python or Javascript coding, and a bit of imagination and decoding trials, you may find things never discovered before.

The first step is to grab the data of block 0, the very first block mined by Satoshi. This is available from https://blockchain.info/block-height/0

This gives us a JSON formatted response:

{"blocks":[{"hash":"000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f","ver":1,"prev_block":"0000000000000000000000000000000000000000000000000000000000000000","mrkl_root":"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b","time":1231006505,"bits":486604799,"next_block":["00000000839a8e6886ab5951d76f411475428afc90947ee320161bbf18eb6048"],"fee":0,"nonce":2083236893,"n_tx":1,"size":285,"block_index":0,"main_chain":true,"height":0,"weight":1140,"tx":[{"hash":"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b","ver":1,"vin_sz":1,"vout_sz":1,"size":204,"weight":816,"fee":0,"relayed_by":"0.0.0.0","lock_time":0,"tx_index":2098408272645986,"double_spend":false,"time":1231006505,"block_index":0,"block_height":0,"inputs":[{"sequence":4294967295,"witness":"","script":"04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73","index":0,"prev_out":null}],"out":[{"type":0,"spent":false,"value":5000000000,"spending_outpoints":[],"n":0,"tx_index":2098408272645986,"script":"4104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac","addr":"1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"}]}]}]}

We'll look closer at two values, "time" and "script" (aka coinbase)

The time value is 1231006505, which looks like it might be a Unix epoch value. Stuffing it into https://www.epochconverter.com/ gives us a value of "Saturday, January 3, 2009 6:15:05 PM GMT", which is indeed when Satoshi mined the very first block.

We know he used this mining opportunity to include a message. Let's see what the message is, exactly, by decoding the "script" field. This is a bunch of hex digits we can convert to ASCII on a site like https://www.rapidtables.com/convert/number/hex-to-ascii.html

Pasting in the hex value 04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73, we get this result:

<some other data> The Times 03/Jan/2009 Chancellor on brink of second bailout for banks

This is the article Satoshi is referring to: https://www.thetimes.co.uk/article/chancellor-alistair-darling-on-brink-of-second-bailout-for-banks-n9l382mn62h

Now take a look at the paper version Satoshi probably read: https://imgur.com/pGYXHJh

That's right. The small heading on the top says "Start collecting tokens today".

How fitting.