Bitcoin exercise

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If you're reading this likely I have given you a paper bitcoin wallet containing a small balance of bitcoin. A typical amount might be 10 millibitcoin [10 mBTC] (10 thousandths of a bitcoin). At the time of writing 1 BTC is worth approx £500.00 and therefore 10 mBTC is about £5.00.

The wallet has two keys, the public address and the private key. You should not reveal the private key to anyone as the contents of the wallet can be transferred or spent or stolen by anyone who has seen the private key. If the private key to the wallet is lost then the bitcoins in the wallet are lost too, irretrievably: Nobody anywhere will ever have access to them again. They can never be spent or transferred to anyone else without the private key.

It is safe to reveal the public address. The public address can be used to show the balance of the wallet or to load it with more bitcoin, it cannot be used to spend or transfer the bitcoin.

You can read the balance of the bitcoin wallet I gave you by scanning its public address at any of several web sites including Be careful not to scan the wallet's private key as the website can then steal your bitcoin!

Your task, should you choose to accept it, is to return to me exactly 1 millibitcoin (1 mBTC). You can either send it to my bitcoin wallet, with the help of the form at, or you could return me the paper wallet I gave you with only 1 mBTC left on it.

In the past the above is as much help as I would give anyone. But nobody was attempting or completing the task! To send me 1 mBTC I suggest you do as follows:

(1) Create your own bitcoin wallet either on paper using or online in the cloud at or on your own computer's disk using software freely downloadable from the likes of

(2) Transfer the entire balance of the wallet I gave you to your new wallet, so that I can't later steal from you - I know your private key. You can do this by various means. I would suggest you use either the web site or the Electrum software maybe you now have on your PC. You will notice a tiny transaction fee is taken. This is the reward you assign the bitcoin miner who adds the transaction to the bitcoin transaction log, the "blockchain".

(3) Then, either from Electrum or or from other similar services, you will be able to send me 1 mBTC. Will you avoid sending me your entire balance by mistake? And will you lose your change?

If you don't empty the wallet I have given you then I will assume you're not taking part. Eventually I will transfer any remaining balance on that wallet back to me so that the bitcoin are not lost forever. I can do this because I have sneakily kept a record of the private key.

If you empty the paper wallet, you're welcome to its contents. Do try to send me 1 mBTC, see if you can!

Paul Beardsell

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