3 ms·
Transactions are valid only when you trust you have the longest chain. If a longer chain comes along, you may abandon the shorter chain and believe the longer c
by jsprogrammer 11y ago
Transactions are valid only when you trust you have the longest chain. If a longer chain comes along, you may abandon the shorter chain and believe the longer chain.
- Kenji 11y agoExactly. But when do you trust you have the longest chain? It could be that by some stroke of misfortune or malicious manipulation, a shorter chain suddenly catches up. Is a chain that is 10 links longer safe? As I said - eventual consistency. But when is eventually? This is a real issue for BTC transaction validation.
- jcoffland 11y agoIf the senaro you describe were remotely possible BitCoin would not exist. A chain more than a couple of blocks behind has almost no chance of catching up unless over 50% of the hashing power consolidated on the shorter chain. Since miners automatically abandon short chains and it is in their best interest to do so this is extremely unlikely.
- the_mitsuhiko 11y agoWhat if mining pools would deliberately hold back mint blocks until they find more? That way they could invalidate transactions if they like.
- jsprogrammer 11y agoYou can only hold a mint block until right before another block arrives. Once another block is known your mint block is garbage.
- the_mitsuhiko 11y ago> You can only hold a mint block until right before another block arrives. Once another block is known your mint block is garbage. What controls this?
- jsprogrammer 11y agoEach block must incorporate the hash from the previous block.
- the_mitsuhiko 11y agoSo what stops you from mining ahead secretly?
- colejohnson66 11y agoMy guess is the difficulty of making a block means it would take too long
- jsprogrammer 11y agoAs colejohnson said, the difficulty. The network, as a whole, expects to generate 1 block approximately every 10 minutes. Someone with less than 50% of the network power will never be able to sustainably mint a longer chain of 'fake' blocks before someone else mints a legit one.
- the_mitsuhiko 11y ago> As colejohnson said, the difficulty. The network, as a whole, expects to generate 1 block approximately every 10 minutes. Someone with less than 50% of the network power will never be able to sustainably mint a longer chain of 'fake' blocks before someone else mints a legit one. If you look at the blocks mined you can see that there are plenty of mining groups that manage to mine consecutive blocks: https://blockchain.info/blocks https://blockchain.info/blocks
- 11y ago
- droffel 11y agoUsually, 1 confirmation is enough. 6 confirmations is considered enough for any amount. Most exchanges are comfortable with letting you use your coins in 2-3 confirmations, and they tend to be very high risk businesses in the space.