Folks:
I don't fully understand this thread, but it sounds like to me it
might be omitting consideration of multi-target attacks. For example,
Tier Nolan's attack
(http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-January/012230.html),
which seems to be the best attack on this thread, se
I'm convinced-- it is a good idea to worry about 80-bit collision attacks
now.
Thanks to all the people smarter than me who contributed to this
discussion, I learned a lot about collision attacks that I didn't know
before.
Would this be a reasonable "executive summary" :
If you are agreeing to l
On Mon, Jan 11, 2016 at 11:57 PM, Tier Nolan wrote:
>
> else:
> script = "CHECKSIG %s OP_DROP" % (prev_hash, const_pub_key)
>
That should be
script = "%s CHECKSIG %s OP_DROP" % (const_pub_key, prev_hash)
___
bitcoin-dev mailing list
bitcoin
On Fri, Jan 8, 2016 at 3:46 PM, Gavin Andresen via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:
> How many years until we think a 2^84 attack where the work is an ECDSA
> private->public key derivation will take a reasonable amount of time?
>
I think the EC multiply is not actually
On Fri, Jan 8, 2016 at 4:50 PM, Gavin Andresen via bitcoin-dev
wrote:
> And to fend off the messag that I bet somebody is composing right now:
>
> Yes, I know about a "security first" mindset. But as I said earlier in the
> thread, there is a tradeoff here between crypto strength and code
> compl
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Hash: SHA512
On 10 January 2016 22:57:15 GMT-05:00, Rusty
>Cheers,
>Rusty.
>[1] Weirdly, the bitcoin network is doing this much work every 57
>days, for about $92M. If that's all the attack costs, it's under
>1M in 10 years.
Don't get too caught up in
Gavin Andresen via bitcoin-dev writes:
> How many years until we think a 2^84 attack where the work is an ECDSA
> private->public key derivation will take a reasonable amount of time?
vanitygen can generate keypairs pretty fast (on my CPU it's comparable
with hashing time), and there are ways to
On Fri, Jan 08, 2016 at 02:00:11PM +1030, Rusty Russell via bitcoin-dev wrote:
> Pieter Wuille via bitcoin-dev
> writes:
> > Yes, this is what I worry about. We're constructing a 2-of-2 multisig
> > escrow in a contract. I reveal my public key A, you do a 80-bit search for
> > B and C such that H(
On Thu, Jan 07, 2016 at 08:54:00PM -0500, Gavin Andresen via bitcoin-dev wrote:
> ---
>
> I'm really disappointed with the "Here's the spec, take it or leave it"
> attitude. What's the point of having a BIP process if the discussion just
> comes down to "We think more is better. We don't care what
And to fend off the messag that I bet somebody is composing right now:
Yes, I know about a "security first" mindset. But as I said earlier in the
thread, there is a tradeoff here between crypto strength and code
complexity, and "the strength of the crypto is all that matters" is NOT
security firs
On Fri, Jan 8, 2016 at 10:46 AM, Gavin Andresen
wrote:
> And Ethan or Anthony: can you think of a similar attack scheme if you
> assume we had switched to Schnorr 2-of-2 signatures by then?
Don't answer that, I was being dense again, Anthony's scheme works with
Schnorr...
--
--
Gavin Andres
On Fri, Jan 8, 2016 at 10:50 AM, Gavin Andresen
wrote:
> But as I said earlier in the thread, there is a tradeoff here between
> crypto strength and code complexity, and "the strength of the crypto is all
> that matters" is NOT security first.
I should be more explicit about code complexity:
T
Thanks, Anthony, that works!
So...
How many years until we think a 2^84 attack where the work is an ECDSA
private->public key derivation will take a reasonable amount of time?
And Ethan or Anthony: can you think of a similar attack scheme if you
assume we had switched to Schnorr 2-of-2 signatur
On Fri, Jan 8, 2016 at 2:54 AM, Gavin Andresen via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:
> I'm saying we can eliminate one somewhat unlikely attack (that there is a
> bug in the code or test cases, today or some future version, that has to
> decide what to do with "version 0"
On Fri, Jan 08, 2016 at 07:38:50AM -0500, Gavin Andresen via bitcoin-dev wrote:
> Lets see if I've followed the specifics of the collision attack correctly,
> Ethan (or somebody) please let me know if I'm missing something:
>
> So attacker is in the middle of establishing a payment channel with
>
Tricky choice. On the one hand I had spotted this too before and maybe
one or two more exceptions to bitcoin's 128-bit security target and
been vaguely tut-tutting about them in the background. It's kind of a
violation of crypto rule of thumb that you want to balance things and
not have odd weak p
On Fri, Jan 8, 2016 at 4:38 AM, Gavin Andresen via bitcoin-dev
wrote:
> On Fri, Jan 8, 2016 at 7:02 AM, Rusty Russell wrote:
>>
>> Matt Corallo writes:
>> > Indeed, anything which uses P2SH is obviously vulnerable if there is
>> > an attack on RIPEMD160 which reduces it's security only marginall
On Fri, Jan 8, 2016 at 7:02 AM, Rusty Russell wrote:
> Matt Corallo writes:
> > Indeed, anything which uses P2SH is obviously vulnerable if there is
> > an attack on RIPEMD160 which reduces it's security only marginally.
>
> I don't think this is true? Even if you can generate a collision in
>
Matt Corallo writes:
> Indeed, anything which uses P2SH is obviously vulnerable if there is
> an attack on RIPEMD160 which reduces it's security only marginally.
I don't think this is true? Even if you can generate a collision in
RIPEMD160, that doesn't help you since you need to create a specif
Indeed, anything which uses P2SH is obviously vulnerable if there is an attack
on RIPEMD160 which reduces it's security only marginally. While no one thought
hard about these attacks when P2SH was designed, we realized later this was not
such a good idea to reuse the structure from P2PKH. Hence
Pieter Wuille via bitcoin-dev
writes:
> Yes, this is what I worry about. We're constructing a 2-of-2 multisig
> escrow in a contract. I reveal my public key A, you do a 80-bit search for
> B and C such that H(A and B) = H(B and C). You tell me your keys B, and I
> happily send to H(A and B), which
On Jan 7, 2016 5:22 PM, "Gavin Andresen via bitcoin-dev" <
bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> On Thu, Jan 7, 2016 at 6:52 PM, Pieter Wuille
wrote:
>>
>> Bitcoin does have parts that rely on economic arguments for security or
privacy, but can we please stick to using cryptography tha
On Thu, Jan 7, 2016 at 8:26 PM, Matt Corallo
wrote:
> So just because other attacks are possible we should weaken the crypto
> we use? You may feel comfortable weakening crypto used to protect a few
> billion dollars of other peoples' money, but I dont.
>
No...
I'm saying we can eliminate one s
So just because other attacks are possible we should weaken the crypto
we use? You may feel comfortable weakening crypto used to protect a few
billion dollars of other peoples' money, but I dont.
On 01/07/16 23:39, Gavin Andresen via bitcoin-dev wrote:
> Thanks, Ethan, that's helpful and I'll stop
On Thu, Jan 7, 2016 at 6:52 PM, Pieter Wuille
wrote:
> Bitcoin does have parts that rely on economic arguments for security or
> privacy, but can we please stick to using cryptography that is up to par
> for parts where we can? It's a small constant factor of data, and it
> categorically removes
Thanks, Ethan, that's helpful and I'll stop thinking that collision attacks
require 2^(n/2) memory...
So can we quantify the incremental increase in security of SHA256(SHA256)
over RIPEMD160(SHA256) versus the incremental increase in security of
having a simpler implementation of segwitness?
I'm
> "The problem case is where someone in a contract setup shows you a
script, which you accept as being a payment to yourself. An attacker could
use a collision attack to construct scripts with identical hashes, only one
of which does have the property you want, and steal coins.
>
> So you really wa
>Ethan: your algorithm will find two arbitrary values that collide. That isn't
>useful as an attack in the context we're talking about here (both of those
>values will be useless as coin destinations with overwhelming probability).
I'm not sure exactly the properties you want here and determini
Based on current GH/s count of 775,464,121 Bitcoin tests 2^80 every 19 days.
log2(775464121*(1000*1000*1000*60*60*24*19)) = ~80.07
I don't fully understand the security model of segwit, so my analysis
will assume that any collision is bad.
>But it also requires O(2^80) storage, which is utterly i
Maybe I'm asking this question on the wrong mailing list:
Matt/Adam: do you have some reason to think that RIPEMD160 will be broken
before SHA256?
And do you have some reason to think that they will be so broken that the
nested hash construction RIPEMD160(SHA256()) will be vulnerable?
Adam: re: "
Maybe I'm being dense, but I don't see why 2**80 storage is required for
this attack. Also, I don't see why the attacker ever needs to get the
victim to accept "arbitrary_data". Perhaps I'm wrong about how the
collision attack works:
1. Create a script which is perfectly acceptable and would
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