33 views

### Exchange Confirmation Requirements

What does the minimum confirmations required for a deposit mean for the security of exchanges? For example, Coinbase requires 3 confirmations for Bitcoin deposits. Suppose an adversary deposits 10 ...
71 views

### Cryptocurrency acceptance

I heard that the recommended waiting confirmation time for a bitcoin transaction is 6 blocks/ 1 hour. So a shop which lets its customer to pay in bitcoin without any waiting for confirmation would ...
45 views

### Understand double spending through an example

Let’s suppose you have 1 BTC which you try to spend twice. You made the 1 BTC transaction to a merchant (Transaction T1). Now, you again sign and send the same 1 BTC on another Bitcoin address to try ...
195 views

### bitcoin reorg question

if a block takes 10 minutes to be mined does it need 21 minutes to be reorged? if the reorg started immediately after the block was mined because 100% was mining and 51.5% will reorg how long does ...
267 views

### How long a high-priority transaction takes to evaluate

I am missing something so far in reading this (excellent resource). I read the part about transactions for the most part, but I don't understand the actual code evaluation part, and how long it takes. ...
94 views

### How could a lightweight wallet determine the validity of 0-conf transaction?

I found that a lot of people are interested about security of 0-confirmation payments. But, it seems that most discussions focused on double-spending (like broadcasting two or more conflicting-but-...
110 views

### Can two or more transactions sent from the same address be mined in the same block in Bitcoin's blockchain?

Imagine a person Bob has 10 bitcoins in his wallet. He wants to send 5 bitcoins to Alice and another 5 bitcoins to Uncle Tom simultaneously (in separate transactions). Will both Bob's transactions be ...
375 views

### What's so special about six blocks for confirming transactions?

I read that when your transaction is part of a block that has five other blocks on top of it, you can feel safe that your transaction is not in danger of being orphaned because someone else would come ...
266 views

### Can I spend a tx before it has 6 confirmations? [duplicate]

When I got a transaction (someone transfer some bitcoins to me), can I use it before the transaction has 6 confirmations?
6k views

### How many confirmations takes place before transaction is successful

Yesterday I attempted to send two bitcoin transfers from Livecoin and almost 24 hours later it hasn't been successful. When I check the transactions they have 99 and 95 confirmations. What does that ...
124 views

### Detection of double spend in Bitcoin for aged transactions

This is just to verify my understanding of Bitcoin double spend detection. 1) Use of UTXO indexes : This ensures that there as been no spend from that output (transferred to recipient in Block of ...
107 views

### How long should I wait to consider that the transation is “definitely” confirmed?

When one transaction is broadcasted, what is the probability that it won't be confirmed? (By probability, I mean the observed probability on the blockchain. If a person intentionally spend twice 1 ...
958 views

### What is the risk of waiting for just one confirmation to validate a transaction, assuming the counterparty is not a miner?

I am trying to determine how many confirmations would be reasonably safe to wait before accepting a Bitcoin transaction from an attacker that is not a miner and hence cannot rely on Finney attacks, ...