Importing private key into bitcoin-qt

[EnchantedMaple]

I've recently imported a private key into the client on a livecd offline computer. I used bitaddress.org to generate an address and private key. I sent some bitcoin to my address and wanted to make sure I could access them with the private key bitaddress.org gave me.

It worked and I verified that my address was in there and the private key works however I have some concern after a few quesstions I asked before and what I read on the wiki about importing private keys.

WARNING

Before reading this page, users should note that messing with ECDSA private keys is very dangerous and can result in losing bitcoins, even long after the import. It is recommended that outside of self-generated vanity addresses, users should never import (or export) private keys 

What does this mean? this is at the wiki. Some other user tried to explain it but I couldnt quite understand and didn't get any answers off anyone else.



Question number 2:

I then came across this message:

  Because bitcoins can only be spent once, when they are spent using a private key, the private key becomes worthless. It is often possible, but inadvisable and insecure, to use the address implemented by the private key again, in which case the same private key would be reused.

What does this mean? I've imported the private key just to verify....but I'm wondering if I can recieve bitcoins in the future and also send any transactions when I need to.

I'm a little concerned about the warnings and want to reassure myself


thanks for your patience.

[1713902001]

1713902001

[Gleb Goodston]

How course you can recieve more bitcoin on that address and when you want to send them all you need to do is import it again or go back to the wallet that you imported it to and send it with a internet connection.

[cr1776]

1. As below, without a link to the page, the context is not 100% clear, but it is probably a warning that the keys are long and it is easy to mess up typing them (although there are safeguards).  There is nothing inherently wrong with it, just easy to mess up. 

2. I am not sure of the exact reference, but the point that is being made is most likely that it is not recommended to reuse addresses.  You can access anything there as long as you have the key.  And reuse it, just not recommended.

As long as you used bitaddress in offline mode, it sounds as if you did things properly.

[Newar]

[...]

WARNING

Before reading this page, users should note that messing with ECDSA private keys is very dangerous and can result in losing bitcoins, even long after the import. It is recommended that outside of self-generated vanity addresses, users should never import (or export) private keys 

What does this mean? this is at the wiki. Some other user tried to explain it but I couldnt quite understand and didn't get any answers off anyone else.

It means if you generate your own private keys you need to trust 100% your random source. A weak random number generator produces weak keys which may only be found about out much later on.

Question number 2:

I then came across this message:

  Because bitcoins can only be spent once, when they are spent using a private key, the private key becomes worthless. It is often possible, but inadvisable and insecure, to use the address implemented by the private key again, in which case the same private key would be reused.

What does this mean? I've imported the private key just to verify....but I'm wondering if I can recieve bitcoins in the future and also send any transactions when I need to.

I'm a little concerned about the warnings and want to reassure myself


thanks for your patience.

There's a privacy issue and a technical for some, but the main issue was with people spending from Bitcoin Core with imported private keys and then they deleted the wallet.dat file. The change from the spent transaction went to a address generated by Bitcoin Core and when that wallet.dat was deleted the change address and private key for it were lost. There's other solutions now, for example Mycelium offers a way around that and makes spending from private keys easy.