Bitcoin Forum

Let's say I lost my USB drive that had a backup (unencrypted) of my wallet.dat

How would I "invalidate" that backup?

Create 101 new addresses and then send all of your coins to the 101^st. Or sent all of your coins to a fresh installation of Bitcoin and then discard your old wallet.

Wouldn't it be enough to just make one transaction from or to each address in your wallet to invalidate the backed up wallet? (consider: http://forum.bitcoin.org/index.php?topic=782.0)

Create a new wallet with entirely new keys.  Transfer your entire balance to one or more of the new keys.

Best answer, I think.

New wallet, send all the coins. Did that when I "moved" from my laptop to my new PC.

all the above answers are valid and inexpensive but suffer from the fact that if someone has already found and spent your coins you're outta luck.

what i have done is gone the expensive route and bought some Ironkeys with malware and Silver Bullet protection.  the Ironkey itself is encrypted but can be accessed with password.  a brute force attack will autodestruct the contents after 10 tries.  this can be set higher or lower if u want.  i've set it up so that immediately upon login Ironkey accesses the malware protection from their server to block any executables from the Internet. yes, i have to trust Ironkey company.  i then have a Truecrypt volume with my wallet.dat inside that i have to mount.  My goal one day is to get a trustable Bitcoin client loaded in the Ironkey once one becomes reliable and available on the Forum.  If i lose my Ironkey, i have the ability to destroy the contents of the key with the Silver Bullet feature which is activated from the Ironkey website.  supposedly these Ironkeys have been taken to the "bottom of the ocean" and returned undamaged.  don't ask me how deep they went!

the above features come with a yearly fee. all this cost me a few hundred dollars but at this pt, considering the number of btc's i own, its definitely worth the peace of mind.

Is it possible to transfer the balance, if the keys of the old wallet account are not available anymore?

No.

This is IMHO one of the core problems if Bitcoin - not "someone looses it", but when mining finally stops, the amount of coins WILL deteriorate over time. Even a small drippling effect WILL slowly reduce butcoins out of existence. Over a long long long time.

Huh? Transaction processing won't stop. Somebody will always be after the transaction fees. If for some reason transaction processing DID stop, THAT would be the end of Bitcoin.

Maybe I still don't get the whole concept, but I understand that due to some computation a bitcoin is represented by a proven hash calculation. So now, the overall volumen is not created yet and there is are still bitcoins mined. But once mining stops, the volume is set. From this time on no more bitcoins can be "created" but they can get "lost" by i.e. people loosing their wallet. I understand that this does not harm the value of the currency, but if I understand it right, the volume will in the best case remain the same or decrease after mining stopped. But there is no way to compensate for lost bitcoins after mining stopped. I guess due to the amount of bitcoins it is considered acceptable to lose some?

Right.