Bitcoin Forum
October 24, 2017, 11:49:14 AM *
News: Latest stable version of Bitcoin Core: 0.15.0.1  [Torrent]. (New!)
 
   Home   Help Search Donate Login Register  
Pages: « 1 [2]  All
  Print  
Author Topic: Feather-forks: enforcing a blacklist with sub-50% hash power  (Read 9104 times)
chriswilmer
Legendary
*
Offline Offline

Activity: 1008


View Profile WWW
October 18, 2013, 02:32:56 AM
 #21


4. A related natural occurrence
Consider the scenario where some user broadcasts a transaction with an anomalously large fee, U₁. Let's say that the chance of winning the next block is α, your proportion of the total power (in hashes/second), and that the typical reward for a block is U₀. Then the expected utility of cooperation (strategy C₀) is (something like):
       E[C₀] = αU₀
In order to earn the enormous reward U₁ (strategy C₁) you'd have to win TWO blocks before the rest of the network wins one:
       E[C₁] = α²U₁
So, in the case that U₁/U₀ ≥ α⁻¹, a rational miner with hashpower α will defect, even if all others cooperate. The larger your share of the hash power, the lower the breakpoint for a prize be to be worth contending over.

Example: Suppose the (fictional) RationalMiningPool accounts for about 33% of the hashpower. A software glitch at MyPHPWebWallet.com results in a submitted transaction with a fee exceeding 75 btc (the typical block reward is only 25 btc). RationalMiningPool does not find the first winning block to include this fee; however, it decides to keep fighting for the big prize, since the chance of finding the next two consecutive solutions is decent and the high value makes it worthwhile.



One funny consequence of this example is that if you offer a really large fee... instead of having your transaction confirm more quickly, it may actually end up taking longer as it keeps ending up in orphaned chains as miners keep fighting over it!
1508845754
Hero Member
*
Offline Offline

Posts: 1508845754

View Profile Personal Message (Offline)

Ignore
1508845754
Reply with quote  #2

1508845754
Report to moderator
Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here.
1508845754
Hero Member
*
Offline Offline

Posts: 1508845754

View Profile Personal Message (Offline)

Ignore
1508845754
Reply with quote  #2

1508845754
Report to moderator
1508845754
Hero Member
*
Offline Offline

Posts: 1508845754

View Profile Personal Message (Offline)

Ignore
1508845754
Reply with quote  #2

1508845754
Report to moderator
1508845754
Hero Member
*
Offline Offline

Posts: 1508845754

View Profile Personal Message (Offline)

Ignore
1508845754
Reply with quote  #2

1508845754
Report to moderator
groll
Sr. Member
****
Offline Offline

Activity: 336


View Profile
October 18, 2013, 02:46:10 AM
 #22

Quote
One funny consequence of this example is that if you offer a really large fee... instead of having your transaction confirm more quickly, it may actually end up taking longer as it keeps ending up in orphaned chains as miners keep fighting over it!

yep and even worst nothing prevent him from adding to it to remove the bounty from everyone if they win as he had done with the first transaction. this until he get the block himself. possible if he have some hash also and many rational are competing.
loiluu
Newbie
*
Offline Offline

Activity: 6


View Profile
January 06, 2016, 08:39:26 AM
 #23

This paper may be relevant to the topic http://people.cs.uchicago.edu/~teutsch/papers/repurposing_miners.pdf. The paper discusses an attack when miners in the network are rational. The paper shows that "a mining pool which controls at least 38.2% of the network’s total computational power can, with modest financial capacity, gain mining advantage over honest mining".
Pages: « 1 [2]  All
  Print  
 
Jump to:  

Sponsored by , a Bitcoin-accepting VPN.
Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2006-2009, Simple Machines Valid XHTML 1.0! Valid CSS!