4 ms·

It quickly gets very expensive to do so.

by cmer 9y ago

CyberDildonics 9y ago
How? If the proof of work only takes a few seconds, what prevents someone from spamming a new transaction every few seconds?
- deleted 9y ago
  [deleted]
- darawk 9y ago
  Transaction fees.
  - gruez 9y ago
    I thought the whole point is free (or very low) transaction fees?
- xur17 9y ago
  I am very curious about this as well. In this example [0] someone was able to precompute 30k transactions in 5 hours with a single 1070. A mining farm with 100 video cards (capital cost of $40k) could generate a sustained load of 10k transactions per second. With precomputation, you could easily do an order of magnitude more damage. All of these transactions are stored permanently on the ledger as far as I can tell. Nanoblocks does serve some purpose in my mind, but it has major issues to solve, and in no way is a catch-all solution for the scaling problems that Bitcoin has. [0] https://hackernoon.com/stress-testing-the-raiblocks-network-568be62fdf6d https://hackernoon.com/stress-testing-the-raiblocks-network-...
  - tobik999 9y ago
    Your calculation is wrong. One 1070 is able to produce about 1.6 txs, so 100 x 1070 are able to produce 160 txs. For a full transaction you need to do two time POW (send and receive), so if you use the same cards to receive the tx also you are only able to produce 80 txs. Right now I do not think you would harm the network up to about 10k - 50k txs (a simple laptop is able to monitor about 1k txs). So you may want to target at least 10k txs, therefore you would need more than 10k graphic cards at a cost of about $500 each at least, this sums up to $5,000,000 and as I said it is not clear that this would harm the net in any substantial way.
    - xur17 9y ago
      My calculations are based on the numbers from the article I linked to. I'm guessing they might have changed the difficulty since that blog post was written? Regardless though, I can precompute the PoW for each transaction, so I could preprocess for a month to get a higher tps.
      - tobik999 9y ago
        It was not changed yet, 30,000tx/18,000seconds=1.6txs
        xur17 9y ago
        You're right. I did my math wrong.
- AndrewSChapman 9y ago
  The Raiblocks / Nano white paper says: B. Transaction Flooding A malicious entity could send many unnecessary but valid transactions between accounts under its control in an attempt to saturate the network. With no transaction fees they are able to continue this attack indefinitely. However, the PoW required for each transaction limits the transaction rate the malicious entity could generate without significantly investing in computational resources. Even under such an attack in an attempt to inflate the ledger, nodes that are not full historical nodes are able to prune old transactions from their chain; this clamps the storage usage from this type of attack for almost all users. and "D. Penny-Spend Attack A penny-spend attack is where an attacker spends infinites- imal quantities to a large number of accounts in order to waste the storage resources of nodes. Block publishing is rate-limited by the PoW, so this limits the creation of accounts and transactions to a certain extent. Nodes that are not full historical nodes can prune accounts below a statistical metric where the account is most likely not a valid account. Finally, RaiBlocks is tuned to use minimal permanent storage space, so space required to store one additional account is proportional to the size of an open block + indexing = 96B +32B = 128B. This equates to 1GB being able to store 8 million penny-spend account. If nodes wanted to prune more aggressively, they can calculate a distribution based on access frequency and delegate infrequently used accounts to slower storage."

It quickly gets very expensive to do so.

by cmer 9y ago

It quickly gets very expensive to do so.

How? If the proof of work only takes a few seconds, what prevents someone from spamming a new transaction every few seconds?

deleted 9y ago
[deleted]
darawk 9y ago
Transaction fees.
- gruez 9y ago
  I thought the whole point is free (or very low) transaction fees?
xur17 9y ago
I am very curious about this as well. In this example [0] someone was able to precompute 30k transactions in 5 hours with a single 1070. A mining farm with 100 video cards (capital cost of $40k) could generate a sustained load of 10k transactions per second. With precomputation, you could easily do an order of magnitude more damage. All of these transactions are stored permanently on the ledger as far as I can tell. Nanoblocks does serve some purpose in my mind, but it has major issues to solve, and in no way is a catch-all solution for the scaling problems that Bitcoin has. [0] https://hackernoon.com/stress-testing-the-raiblocks-network-568be62fdf6d https://hackernoon.com/stress-testing-the-raiblocks-network-...
- tobik999 9y ago
  Your calculation is wrong. One 1070 is able to produce about 1.6 txs, so 100 x 1070 are able to produce 160 txs. For a full transaction you need to do two time POW (send and receive), so if you use the same cards to receive the tx also you are only able to produce 80 txs. Right now I do not think you would harm the network up to about 10k - 50k txs (a simple laptop is able to monitor about 1k txs). So you may want to target at least 10k txs, therefore you would need more than 10k graphic cards at a cost of about $500 each at least, this sums up to $5,000,000 and as I said it is not clear that this would harm the net in any substantial way.
  - xur17 9y ago
    My calculations are based on the numbers from the article I linked to. I'm guessing they might have changed the difficulty since that blog post was written? Regardless though, I can precompute the PoW for each transaction, so I could preprocess for a month to get a higher tps.
    - tobik999 9y ago
      It was not changed yet, 30,000tx/18,000seconds=1.6txs
      - xur17 9y ago
        You're right. I did my math wrong.
AndrewSChapman 9y ago
The Raiblocks / Nano white paper says: B. Transaction Flooding A malicious entity could send many unnecessary but valid transactions between accounts under its control in an attempt to saturate the network. With no transaction fees they are able to continue this attack indefinitely. However, the PoW required for each transaction limits the transaction rate the malicious entity could generate without significantly investing in computational resources. Even under such an attack in an attempt to inflate the ledger, nodes that are not full historical nodes are able to prune old transactions from their chain; this clamps the storage usage from this type of attack for almost all users. and "D. Penny-Spend Attack A penny-spend attack is where an attacker spends infinites- imal quantities to a large number of accounts in order to waste the storage resources of nodes. Block publishing is rate-limited by the PoW, so this limits the creation of accounts and transactions to a certain extent. Nodes that are not full historical nodes can prune accounts below a statistical metric where the account is most likely not a valid account. Finally, RaiBlocks is tuned to use minimal permanent storage space, so space required to store one additional account is proportional to the size of an open block + indexing = 96B +32B = 128B. This equates to 1GB being able to store 8 million penny-spend account. If nodes wanted to prune more aggressively, they can calculate a distribution based on access frequency and delegate infrequently used accounts to slower storage."