Does anybody see flaws or disadvantages in such design?
Sounds like a magic. Is there any other currency that promises instant transactions?
Yes. Ripple XRP.
Topic: [Nxt] Instant transactions with guaranteed confirmation - page 3. (Read 7998 times)
Sounds like a magic. Is there any other currency that promises instant transactions?
Yes. Ripple XRP.
https://bitcointalksearch.org/topic/m.3070839
http://www.netcoin.io/wiki/Secure_and_Instantaneous_Zero-Conf_Transactions_for_Point-of-Sale_Purchase
Check out the above links.
You need to have a mechanism for punishing people who spam zero conf txns in order to doublespend.
http://www.netcoin.io/wiki/Secure_and_Instantaneous_Zero-Conf_Transactions_for_Point-of-Sale_Purchase
Check out the above links.
You need to have a mechanism for punishing people who spam zero conf txns in order to doublespend.
Does anybody see flaws or disadvantages in such design?
Sounds like a magic. Is there any other currency that promises instant transactions?
Any account can not hold more than 1% of the total coins (which is 1 Billion).
Because that's enforceable 
Not only that (I still need to think more, because I am not very attached to POS model yet), but what about a new hard coded rule too:
Any account can not hold more than 1% of the total coins (which is 1 Billion). If we could have more users, even 0.1% is wiser. Besides security concerns, another factor that advises us to force a more normal distribution of coins is having a more liquid transparent ecosystem.
Unlike POW that uses a demand/supply model of coin generation to some points, coin hoarding would be worse for a POS coin and rules like that may help a bit. I know one hoarder can easily set several accounts to bypass this rule, but like rules and stops that manage a city traffic, such 1% (or 0.1%) holding rules may slow down the hoarding rally a bit
Any account can not hold more than 1% of the total coins (which is 1 Billion). If we could have more users, even 0.1% is wiser. Besides security concerns, another factor that advises us to force a more normal distribution of coins is having a more liquid transparent ecosystem.
Unlike POW that uses a demand/supply model of coin generation to some points, coin hoarding would be worse for a POS coin and rules like that may help a bit. I know one hoarder can easily set several accounts to bypass this rule, but like rules and stops that manage a city traffic, such 1% (or 0.1%) holding rules may slow down the hoarding rally a bit
This thread is dedicated to discussion of Nxt features (https://bitcointalksearch.org/topic/ann-nxt-descendant-of-bitcoin-303898), don't confuse it with Bitcoin or other altcoins.
In Bitcoin a payment is made by transferring all coins from input to output addresses with difference between input and output paid as transaction fee. If someone wants to send only part of the coins they must send the rest back to one of their own addresses. An attempt to use the same input twice is a double-spending, only one of the transactions will be confirmed even if enough money is sent back.
Unlike Bitcoin and its forks, Nxt uses a single account instead of multiple addresses for each user. It is possible to send multiple transactions from the same source address (called "account"), all these transactions will be confirmed if the account holds enough coins. Someone still can attempt a double-spending by paying for something with low fee and then sending all their coins to other account with higher fee, making it impossible to confirm the first payment.
We can counteract a double-spending attack in Nxt by using special accounts. A special account has certain limits that don't let to create transactions for more than (for example) 1/10th of the balance in total within a 24 hour timeframe. The network will simply ignore transactions and blocks that violate this rule.
A merchant (or a vending machine) can accept payments from special accounts without waiting for confirmations. The only thing should be done is checking that a received transaction doesn't violate the rule.
Does anybody see flaws or disadvantages in such design?
P.S. Payment privacy in Nxt will be provided via mixing.
In Bitcoin a payment is made by transferring all coins from input to output addresses with difference between input and output paid as transaction fee. If someone wants to send only part of the coins they must send the rest back to one of their own addresses. An attempt to use the same input twice is a double-spending, only one of the transactions will be confirmed even if enough money is sent back.
Unlike Bitcoin and its forks, Nxt uses a single account instead of multiple addresses for each user. It is possible to send multiple transactions from the same source address (called "account"), all these transactions will be confirmed if the account holds enough coins. Someone still can attempt a double-spending by paying for something with low fee and then sending all their coins to other account with higher fee, making it impossible to confirm the first payment.
We can counteract a double-spending attack in Nxt by using special accounts. A special account has certain limits that don't let to create transactions for more than (for example) 1/10th of the balance in total within a 24 hour timeframe. The network will simply ignore transactions and blocks that violate this rule.
A merchant (or a vending machine) can accept payments from special accounts without waiting for confirmations. The only thing should be done is checking that a received transaction doesn't violate the rule.
Does anybody see flaws or disadvantages in such design?
P.S. Payment privacy in Nxt will be provided via mixing.
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