Quote from: penguin_brian on January 23, 2013, 11:44:05 PM

Quote from: RodeoX on January 23, 2013, 08:23:36 PM

A confirmation means that your transaction has been included in a block. More confirmations means that the transaction is being buried deeper in the block chain. Because it is possible to create a fake block chain more than one confirmation is needed. If the block was fake, it will be rejected before a few confirmations.

[/attempt at non-technical explanation]

So if I understand this correctly, it is considered a lot harder to fake a longer chain then a small chain, so the longest chain wins[1].

Would it be possible to insert a fake block, and then trick the other miners that this is the real block, and they should generate a new block based on this fake one?

Notes
[1] hence the concerns with the 51% attack.
https://bitcointalk.org/index.php?topic=52388.0
https://bitcointalk.org/index.php?topic=53647.0
etc

Simple version is no. There is no such thing as a "fake" block. Either the block is valid or it is invalid. An attacker could broadcast invalid blocks on the network, however it is trivial to validate a block. The average CPU can validate a block in a fraction of a second so it isn't much of an attack. No miner is going to build upon a block until they validate it. If the block doesn't validate it will be discarded.