3 ms·

It is pretty hard to cite the lack of a security definition and the lack of a security proof. As for the polynomial time attack, it is describe in the original

It is pretty hard to cite the lack of a security definition and the lack of a security proof. As for the polynomial time attack, it is describe in the original Bitcoin paper, at the end of Section 4: http://bitcoin.org/bitcoin.pdf http://bitcoin.org/bitcoin.pdf It is also described here: https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_... And in this criticism by Ben Laurie: http://www.links.org/files/decentralised-currencies.pdf http://www.links.org/files/decentralised-currencies.pdf

maaku 13y ago
Ok, that's not an attack against the cryptography of the system, which you're original post implied. E.g, you can't use a polynomial-time algorithm to spend coins which belong to me.
- betterunix 13y ago
  "that's not an attack against the cryptography of the system" I am not sure what you mean. What do you think this is an attack against? "you can't use a polynomial-time algorithm to spend coins which belong to me." In some situations I can. If, for example, you received your money from me, I can take the money from you and transfer it to someone else. The attacker can also stop you from completing transactions and stop you from receiving rewards for mining.
  - maaku 13y ago
    Again, I'm not sure I'd call a reiteration of the design criteria an attack or weakness of the system. Bitcoin was designed to operate by 51% proof-of-work consensus. It's a feature, not a flaw. It's kinda like saying democracy is broken because you could be unseated by a 51% vote.
    - betterunix 13y ago
      The difference between Bitcoin's vulnerability and democratic systems is pretty clear: in a democratic system, 51% of the participants control the outcome; in Bitcoin, a single participant doing 51% of the work can control the system. It is equivalent to allowing every single voter to fill out as many ballots as they can on election night, using whatever equipment they happen bring with them.

maaku 13y ago

Ok, that's not an attack against the cryptography of the system, which you're original post implied. E.g, you can't use a polynomial-time algorithm to spend coins which belong to me.

betterunix 13y ago
"that's not an attack against the cryptography of the system" I am not sure what you mean. What do you think this is an attack against? "you can't use a polynomial-time algorithm to spend coins which belong to me." In some situations I can. If, for example, you received your money from me, I can take the money from you and transfer it to someone else. The attacker can also stop you from completing transactions and stop you from receiving rewards for mining.
- maaku 13y ago
  Again, I'm not sure I'd call a reiteration of the design criteria an attack or weakness of the system. Bitcoin was designed to operate by 51% proof-of-work consensus. It's a feature, not a flaw. It's kinda like saying democracy is broken because you could be unseated by a 51% vote.
  - betterunix 13y ago
    The difference between Bitcoin's vulnerability and democratic systems is pretty clear: in a democratic system, 51% of the participants control the outcome; in Bitcoin, a single participant doing 51% of the work can control the system. It is equivalent to allowing every single voter to fill out as many ballots as they can on election night, using whatever equipment they happen bring with them.