I sold my second hand S1 on eBay UK, and was paid via PayPal without any problems.

Isn't this just a misquote, and/or statments from people who don't know what Bitcoin is?

I read it, very simply, as "he was mining bitcoins using stolen power".  The 21 "computers", were probably just S1's or something.

Thanks Guys.

This has been both very helpful and extremely interesting.

With regards to the private key / public key / Bitcoin address thing, are we saying:

1) A Bitcoin address can be calculated from a public key,
2) A public key can be calculated from a private key.

So the *only* thing one needs to worry about (from a backup point of view, and for each Bitcoin address) is it's corresponding private key, which *must* be kept secure - Presumably this is one of those calculations such as 10 * 3 (always) = 30, but 30 could be derived from a number of different calculations (1 * 30, 2 * 15, 3 * 10 etc). - Except obviously slightly more complex than that :-)

So, sometimes when I send Bitcoins, behind the scenes, I'm actually sending more, and waiting for change (just as I would in the local store with paper money).  However, when that chance comes back, it may/will go into a new Bitcoin address which I wasn't previously aware of.

Does that mean that if I'm using cold storage, it's not good enough to simply restore the private key, spend some Bitcoins, and take it off-line again, as I may find more has gone *from that Bitcoin address* than I was expecting - Unless I sweep(?) all Bitcoins to the same address.

I think I'm starting to understand! Thanks :-)

Hi,

I'm a little new to Bitcoin, and although I've learned a lot over the last week or so, I'm still a little unclear about a few things which I hope the community will be able to help me out with!

I understand (I think!) that each public key (the wallet address?) has corresponding private key.  You could have an "off-line" wallet, by writing down your private and public keys, and then deleting the wallet file(?).  You should then me about to import both your keys at some point in the future into any Bitcoin wallet software, and access your bitcoins again.  In the meanwhile, you can still give people your public key, and it can still be used to send Bitcoins too.

(Is that right?)

I'm using Bitcoin QT, and it allows me to create a number of different wallets.  Presumably if I wanted to make a note of the private key for each one, I'd ender the console mode in Bitcoin QT, and type the command to display the private key for any one of the wallets?

What confused me, is that the other day I used BTC to buy something.  I had (for example) 1.5 BTC in my wallet, so I sent 1.2 BTC to the person I was paying, obviously leaving 0.3 in my wallet.  That all happened perfectly.  But today, when I thought I'd have a look at the blockchain, I see that, although Bitcoin QT correctly says my wallet contains 0.3 BTC, if I add up the "Final Balance" of the 3 different public key addresses I have listed, it comes to something like 0.1 BTC.  The remaining 0.2 BTC, although I can see see it, appears to have been transferred to a different public address at the same time I paid the 1.2 BTC the other day.

The point is, I know this is still "mine", because it shows up in my confirmed balance in Bitcoin QT, but I don't understand the mechanism which appeared to create a new(?) public address, and transferred the 0.2 to it.

Also, this presumably means the 0.3 BTC I have is arbitrarily spread around my different wallets?  If I wanted to take that 0.3 BTC off-line, how would I know which wallet, or wallets it was in? - And as it appears that a public address has been created for me without me knowing, how would I find it unless I did what I did, which was to look at that particular transaction in the blockchain?

I'm sorry for asking, what I suspect are quite basic questions, but I'm interested to know how it works!

Thanks.