What number of confirmations is considered secure in Ethereum?
In Bitcoin, 6 confirmations are considered secure (very low probability of transaction/block reversal).
What is the current number in Ethereum?
Eth, you are talking about confirming a block here, right? I ask because of the comment lungj made to my question here: https://ethereum.stackexchange.com/questions/21686/what-are-the-differences-and-relationship-between-the-steps-used-to-1-valida - Your clarification, would be great.
@Tesa I understand the terminology isn't great. You would say a transaction has 6 confirmations; but we don't really say that blocks get confirmed and it's unusual to say that a block has 6 confirmations. A well-written definition from Bitcoin: "confirmations represent the number of blocks in the block chain that have been accepted by the network since the block that includes the transaction." (When we get to Proof of Stake, there are notions of blocks getting finalized.)
From George Hallam:
12 confirmations; however, exchanges and entities handling very large amounts of Ether frequently are still encouraged to run two different Ethereum implementations and only accept transactions that have been confirmed by both for maximum security (e.g. Go & C++).
For reference, 12 confirmations is approximately 3 minutes.
Can you please provide a reference to why 12 confirmations is a good number?
This article discusses waiting an on appropriate value to be gathered by miners before considering the transaction complete. The value is proportional to the value you are transacting. Called the 'Ou Rule' in the article: https://medium.com/@nic__carter/its-the-settlement-assurances-stupid-5dcd1c3f4e41