If people split their bitcoins in multiple addresses, then maybe there would be no need to worry(?), because the computational cost would be higher than what the attacker would get.


https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html

Here are some numbers that give a sense of how large scale this computation was:
  • Nine quintillion (9,223,372,036,854,775,808) SHA1 computations in total
  • 6,500 years of CPU computation to complete the attack first phase
  • 110 years of GPU computation to complete the second phase

https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html
Richest address: 124,178 BTC ($142,853,079 USD)



On Sat, Feb 25, 2017 at 6:40 PM, Peter Todd via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
On Sat, Feb 25, 2017 at 03:34:33PM -0600, Steve Davis wrote:
> Yea, well. I don’t think it is ethical to post instructions without an associated remediation (BIP) if you don’t see the potential attack.

I can't agree with you at all there: we're still at the point where the
computational costs of such attacks limit their real-world impact, which is
exactly when you want the *maximum* exposure to what they are and what the
risks are, so that people develop mitigations.

Keeping details secret tends to keep the attacks out of public view, which
might be a good trade-off in a situation where the attacks are immediately
practical and the need to deploy a fix is well understood. But we're in the
exact opposite situation.

> I was rather hoping that we could have a fuller discussion of what the best practical response would be to such an issue?

Deploying segwit's 256-bit digests is a response that's already fully coded and
ready to deploy, with the one exception of a new address format. That address
format is being actively worked on, and could be deployed relatively quickly if
needed.

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