New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

defense against timewarp attack #696

Closed
zookozcash opened this Issue Jan 29, 2016 · 8 comments

Comments

@zookozcash

zookozcash commented Jan 29, 2016

https://github.com/bitcoin/bips/blob/master/bip-0099.mediawiki

Seems to say that timewarp attack was used in practice against altcoins. This is news to me because I thought it wasn't easily exploited in practice, so I asked for clarification on #bitcoin-wizards:

<Luke-Jr> Thoughts on doing a hardfork dry-run after the whole scalability
      thing has cooled off? We could change the address version bytes and
      payment protocol so the new version is incompatible with old,
      without touching the consensus layer; this would simulate a hardfork
      at an economic level (as much as possible without economic losses),
      and from that hopefully we can learn enough to do a hardfork in the
      future safely.  [21:10]
<zooko> Luke-Jr: interesting idea. It reminds me of jtimon's proposal at SB/HK
    "Let's have an uncontroversial hard fork!".  [21:14]
<Luke-Jr> zooko: well, hopefully the next hardfork proposal will be
      uncontroversial anyway - this can help prepare for it ;)
<jtimon> zooko you mean bip99 still in draft waiting for coauthors to just
     pick up and implement ovious things from the various hardfork
     wishlists?  [21:18]
* zooko looks at
  https://github.com/bitcoin/bips/blob/master/bip-0099.mediawiki
<jtimon> s/ovious/obvious  [21:19]
<zooko> whoa I need to actually pay attention to this, apparently.
<zooko> Are you telling me that the timewarp attack actually was used against
    altcoins ?
<jtimon> zooko of course it was used against altcoins, that's why almost most
     altcoins fixed it (probably the fact that most altcoins just forked
     litecoin was a factor too)
<zooko> jtimon: huh, I thought it wasn't exploitable in practice. So I guess I
    really do need to pay attention! Thanks for mentioning it.
@kanzure

This comment has been minimized.

Contributor

kanzure commented Jan 29, 2016

@zookozcash

This comment has been minimized.

zookozcash commented Jan 29, 2016

@ebfull

This comment has been minimized.

Contributor

ebfull commented Jan 29, 2016

This is the one we want to apply: freicoin/freicoin@beb2fa5

@daira

This comment has been minimized.

Contributor

daira commented Jan 30, 2016

+1

@ebfull

This comment has been minimized.

Contributor

ebfull commented May 25, 2016

We get this for free depending on our difficulty adjustment algorithm, right?

@str4d

This comment has been minimized.

Contributor

str4d commented May 26, 2016

Yes; this fix only needs to be applied if we simply modify the existing difficulty adjustment algorithm. If we take alternate code then this fix will not apply (but we should still check that the alternate code is not itself vulnerable).

@defuse

This comment has been minimized.

Contributor

defuse commented Jun 13, 2016

Related: #998

@nathan-at-least

This comment has been minimized.

Contributor

nathan-at-least commented Jun 13, 2016

Fixed / made-irrelevant in #1004.

zkbot pushed a commit that referenced this issue Jun 15, 2016

zkbot
Auto merge of #1004 - str4d:931-difficulty-algorithm, r=ebfull
Implement new difficulty algorithm

Closes #931. Closes #696.

@zkbot zkbot closed this in #1004 Jun 16, 2016

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment