Subject: Re: [bitcoin-dev] Time to worry about 80-bit collision attacks or not?

From: Gavin Andresen <[email-masked]>
Date: Thu, 7 Jan 2016 20:00:42 -0500

On Thu, Jan 7, 2016 at 6:52 PM, Pieter Wuille <[email-masked]>
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 the worry about security levels.
>
Our message may have crossed in the mod queue:

"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 believe the history of computer security is that implementation errors
and sidechannel attacks are much, much more common than brute-force breaks.
KEEP IT SIMPLE.

(and a quibble:  "do a 80-bit search for B and C such that H(A and B) = H(B
and C)"  isn't enough, you have to end up with a C public key for which you
know the corresponding private key or the attacker just succeeds in burning
the funds)

-- 
--
Gavin Andresen