# Bitcoin networks surpasses 2^80 hashes per week

• To: [email protected]
• Subject: Bitcoin networks surpasses 2^80 hashes per week
• From: [email protected] (Georgi Guninski)
• Date: Wed, 17 Dec 2014 17:47:02 +0200
• References: <CAO7N=i14U5NpZz2OgWGjpzMD0m5HN-TK2sDrwYqH332_2HbVFA@mail.gmail.com> <CACaGApmfbrSUj+DCC+FETTdYzQ3+iNh3ewoFhaG9BSg=zQnggg@mail.gmail.com> <CAO7N=i2MVNgDm9ymyy6ZJ51QP_Xxhh_+PghaGyYtVumxiCT8eQ@mail.gmail.com>

```On Mon, Dec 08, 2014 at 09:44:22AM -0800, Ryan Carboni wrote:
> 24 = hours
> 60 = minutes
> 7 = days
>
> so I'm only off by a factor of 2^3.3, not by a factor of 2^9.3
>
>
> Cheers.
>

Isn't this enough to find 128 bit md5 collision?

Appears to me they can do it distributed in about
2 days even with the most naive rho attack.

AFAIK it is open problem if 128 bit md5 collision exists
(though it is believed to exist).

> On Mon, Dec 8, 2014 at 3:23 AM, Joseph Birr-Pixton <[email protected]>
> wrote:
>
> > On 8 December 2014 at 10:40, Ryan Carboni <[email protected]> wrote:
> > > https://blockexplorer.com/q/hashestowin
> > > log(171833398380382098659*24*60*7)/log(2)
> >
> > I think your calculation is slightly off. hashestowin is the average
> > number of hashes you need to perform to win the current block. It's
> > not necessarily the case that a block is calculated each second: in
> > fact one is found (on average) each 625 seconds[1].
> >
> > So that gives:
> >
> > >>> log(171833398380382098659*24*60*7/625)/log(2)
> > 71.23
> >
> > Cheers,
> > Joe
> >
> > [1] https://blockexplorer.com/q/interval
> >

```