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Why Google is Hurrying the Web to Kill SHA-1

konklone.com

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Re: Why Google is Hurrying the Web to Kill SHA-1

#61

Post by Someone1234 »

konklone wrote: post #44
michaelbuckbee wrote: post #41

A while back I launched a SSL scanner [1] and got tons of feedback from people at Facebook, Google, Microsoft. The most divisive item was how to represent SHA1 deprecation. The OPs article doesn't really touch on it, but the reason that Google and everyone else haven't moved on is that there still exist a sizeable number of clients that can only accept SHA1 (and will error on anything else). I actually suspect that l…

a) This is great. Also, a friend linked me to Expedited SSL yesterday and I link to it in the bottom of this post. b) I think its SHA-1 scanner is mistaken - it flags my site as using SHA-1, but it's SHA-2 in every cert in its chain: https://www.expeditedssl.com/simple-ssl-scanner/scan?target_...

The root CA, USERTrust, is SHA-1 signed.

Everything else is SHA-2 however as you said.

Re: Why Google is Hurrying the Web to Kill SHA-1

#62

Post by michaelbuckbee »

konklone wrote: post #44
michaelbuckbee wrote: post #41

A while back I launched a SSL scanner [1] and got tons of feedback from people at Facebook, Google, Microsoft. The most divisive item was how to represent SHA1 deprecation. The OPs article doesn't really touch on it, but the reason that Google and everyone else haven't moved on is that there still exist a sizeable number of clients that can only accept SHA1 (and will error on anything else). I actually suspect that l…

a) This is great. Also, a friend linked me to Expedited SSL yesterday and I link to it in the bottom of this post. b) I think its SHA-1 scanner is mistaken - it flags my site as using SHA-1, but it's SHA-2 in every cert in its chain: https://www.expeditedssl.com/simple-ssl-scanner/scan?target_...

Thanks for the link! Also, I'm investigating the issue as you are correct that your certs all look good.

Re: Why Google is Hurrying the Web to Kill SHA-1

#63

Post by bpoyner »

taf2 wrote: post #25

The issue here is old clients... Does anyone know how old clients would handle SHA-2 certs, would they just get a warning saying the site is insecure but still be able to visit the site over an encrypted connection or do they break completely... I guess - I'll have to run a few tests this afternoon and see how windows XP performs.

Please let us know. Here's a table showing when SHA-2 support was added to various browsers.

http://en.wikipedia.org/wiki/Transport_Layer_Security#Web_br...

Re: Why Google is Hurrying the Web to Kill SHA-1

#64

Post by Someone1234 »

cbhl wrote: post #33
personZ wrote: post #16

Earlier quoted context omitted.

If going SHA-2 only requires a request flag, why so long for a transition? Is there some downside (e.g. old clients that don't support it) that holds Google off?

Windows XP SP 2 (SP 3 is fine) and early Android, I believe, are the clients that don't support certs later than SHA-1.

There are also other (mostly unsupported) mobile devices which don't. Like old ebook readers which have browsers for some reason.

Re: Why Google is Hurrying the Web to Kill SHA-1

#65

Post by konklone »

Someone1234 wrote: post #61
konklone wrote: post #44

Earlier quoted context omitted.

a) This is great. Also, a friend linked me to Expedited SSL yesterday and I link to it in the bottom of this post. b) I think its SHA-1 scanner is mistaken - it flags my site as using SHA-1, but it's SHA-2 in every cert in its chain: https://www.expeditedssl.com/simple-ssl-scanner/scan?target_...

The root CA, USERTrust, is SHA-1 signed. Everything else is SHA-2 however as you said.

That's right, but the root cert is not sent by the server (in my case). More importantly, SHA-1 isn't a problem for root certs, as their signature is not used to verify their integrity.

Re: Why Google is Hurrying the Web to Kill SHA-1

#66

Post by gbhn »

raldi wrote: post #49
squeaky-clean wrote: post #47

Earlier quoted context omitted.

This entire article is about Why. Read the "An attack on SHA-1 feels plenty viable to me" section for the most info.

I see -- it's not announcing any news, or any new theories; it's just a roundup of last week's news.

Yes. Much like last week's news was. :-)

Re: Why Google is Hurrying the Web to Kill SHA-1

#67

Post by pbsd »

valarauca1 wrote: post #22
brador wrote: post #6

Earlier quoted context omitted.

Botnet.

As I stated. The computation power needed to break SHA-1 is higher then attacking RSA. So if you are financially motivated attacking RSA has a higher ROI.

> The computation power needed to break SHA-1 is higher then attacking RSA[-1024].

You better back that assertion with something. Even in the worst possible case (for SHA-1), it seems to me that SHA-1 is cheaper to collide than it is to factor a general 1024-bit integer.

Re: Why Google is Hurrying the Web to Kill SHA-1

#68

Post by mlissner »

mike_hearn wrote: post #50
bla2 wrote: post #36

It's surprising how much energy Certificate Authorities invest into arguing about this. Instead, they should invest that energy into improving their SHA-2 support and helping their customers migrate.

They are businesses. Their customers are mostly businesses. SHA1 is, for most businesses that only want a padlock to reassure their customers, just peachy. A CA that hassles their customers and says "you need to do complicated extra work" is put at a disadvantage to other CA's that have a "customer is always right" kind of attitude. Combined with tools that default to SHA1, and customers that may depressingly actuall…

What's weird though is that they have a consortium. They could have all agreed simultaneously to stop issuing SHA1 certs years ago and at no market loss. But they didn't.

Re: Why Google is Hurrying the Web to Kill SHA-1

#69

Post by jgrahamc »

kilovoltaire wrote: post #19

Seems like the SSL certificates that CloudFlare automatically generates for sites are SHA-1 signed. Anyone know if they're planning to upgrade to SHA-2?

We are going to do the following:

1. Reissue our SHA-1 based certs to meet the deadlines specified by Chrome so that no customer sees a warning in Chrome.

2. In the future, we will also have an automatic fallback system so that for poor clients (that only support SHA-1) we are able to dynamically provide 'old' certificates. For up to date clients we will not use SHA-1 at all.

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