We have broken SHA-1 in practice

>...That means Git and unknown number of other widely used services that rely on SHA1 have THREE MONTHS to wean themselves and their users off the insecure function

https://arstechnica.com/security/2017/02/at-deaths-door-for-...

Re: We have broken SHA-1 in practice

#6

Post by singularity2001 » Thu, Feb 23, 2017, 1:20 PM UTC

> 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

So no need to panic or urgently switch, but time to slowly transition

Re: We have broken SHA-1 in practice

#7

Post by mshenfield » Thu, Feb 23, 2017, 1:22 PM UTC

StackOverflow post explaining how Git would handle a SHA-1 collision

http://stackoverflow.com/questions/9392365/how-would-git-han...

Re: We have broken SHA-1 in practice

#8

Post by necessity » Thu, Feb 23, 2017, 1:22 PM UTC

> If you use Chrome, you will be automatically protected from insecure TLS/SSL certificates, and Firefox has this feature planned for early 2017.

No need to wait. The option to reject SHA-1 certificates on Firefox is `security.pki.sha1_enforcement_level` with value `1`.

https://blog.mozilla.org/security/2016/01/06/man-in-the-midd...

Other configs worth doing:

`security.ssl.treat_unsafe_negotiation_as_broken` to `true` and `security.ssl.require_safe_negotiation` to `true` also. Refusing insecure algorithms (`security.ssl3.`) might also be smart.

Re: We have broken SHA-1 in practice

#9

Post by amalcon » Thu, Feb 23, 2017, 1:22 PM UTC

singularity2001 wrote: post #6

> 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 So no need to panic or urgently switch, but time to slowly transition

It's been time to slowly transition for the better part of a decade. Still, if you need to start now, it's better late than never.

Re: We have broken SHA-1 in practice

#10

Post by adrianN » Thu, Feb 23, 2017, 1:23 PM UTC

singularity2001 wrote: post #6

> 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 So no need to panic or urgently switch, but time to slowly transition

How much is that in AWS dollars?