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Questions tagged [time-warp-attack]

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Is it feasible to prove the density of found hashes and could that be valuable?

Background When a miner claims a certain hash power and timestamps a block they solved, they are making a claim that a certain amount of time has passed since they received the previous block. ...
Dave Scotese's user avatar
10 votes
1 answer
3k views

What is time warp attack and how does it work in general?

I am trying to understand the recent time warp attack on verge but since the attack is universal across all POW block chain i figure I could also ask here since people here are .. more knowledgeable. ...
Zhen Liu's user avatar
  • 203
9 votes
1 answer
1k views

What prevents similar time-warp attacks in Bitcoin as happened to Verge?

Right now (may 2018), Verge (an altcoin with proof of work) was attacked by time-warp attack. More can be read here https://blog.theabacus.io/the-verge-hack-explained-7942f63a3017 What exactly ...
Karel Bílek's user avatar
  • 2,705
4 votes
1 answer
2k views

How does a time warp attack work?

I more or less understand how an attacker (with less than 50%+1 of the hashing power) can artificially lower the block difficulty by messing with timestamps. I also understand how such an attacker ...
Cedric Martin's user avatar
5 votes
1 answer
356 views

Was the time warp attack the only reason it was not safe to compare chains by length?

One of the weaknesses of bitcoin listed on that wiki is that it was once vulnerable to the time warp attack. This attack lets a miner with >50% of the hash power to solve many more blocks in a short ...
morsecoder's user avatar
  • 14.2k
5 votes
2 answers
1k views

How could a time warp attack be prevented?

jarpian explains what a time warp attack (AKA zeitgeist attack) is: This is a 51% attack where the attacker sets the block timestamps artificially to lower the difficulty, allowing him to profit ...
Nick ODell's user avatar
  • 29.4k
9 votes
2 answers
2k views

Where exactly is the "off-by-one" difficulty bug?

I read through How is difficulty calculated? and want to understand where the "off-by-one" bug is in calculating difficulty. Here is a Matlab snipet I wrote to calculate difficulty. What are the ...
Cal Abel's user avatar
  • 141
21 votes
1 answer
1k views

Gaming the "off-by-one" bug (difficulty re-target based on 2015 instead of 2016 block time span)?

In this forum post from Gavin Andresen he writes: Second: I've written 'discourage blocks' infrastructure: https://github.com/gavinandresen/bitcoin-git/tree/discourageblocks (code reviews ...
kirian's user avatar
  • 3,289
15 votes
1 answer
2k views

What is the "zeitgeist attack"? Does it affect all blockchain technologies?

What exactly is this attack? It would be nice to have a good explanation of how it works and which chains can be effected by this. Does it apply to the bitcoin main chain, or only the newer and ...
MaxSan's user avatar
  • 3,855