Monthly Archives: August 2014

What are some upsides of googles’s SHA1 deprecation plan?

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NOTE: Google has since adopted a more gradual plan for migration which will addresses the potential false sense of urgency the prior plan represented. Personally I think the new plan is a good one. The upsides in this post are still accurate and it is my hope people switch to SHA256 based certificates as quickly as possible.

The Internet is about to embark on another Heartbleed-esq certificate migration. This time there is no immediate danger (which was certainly not the case with Heartbleed) and there is a proposed twelve weeks to plan and respond.

During this time (unless that plan changes) a large majority of the SSL secured Internet will need to swap out their SSL certificates or the users of these sites will see a little scarier user experience. To be fair some of these certificates will be expiring regardless and need to be replaced anyway but this still represents a large number of additional sites that will need to replace certificates sooner than they had planned.

That said there are upsides, for example given how many of the top sites now use SSL the users of these sites will need to move to modern browsers not dependent on platform crypto or update to a newer version of Windows in the process gaining access  to modern web technologies and security fixes.

Another benefit is that CAs that are not active participant in the CABFORUM and who do not follow the root program requirements closely will be sure to stop their use of SHA1 based signatures as soon as they see the user experience impacted.

The same thing will be true of device companies and enterprises who do not as of today have the option to participate in the CABFORUM and even if they did are frankly unlikely to. That is when they see their support calls go up they will change their products and/or processes so that such certificates are not used.

The net of which is by the end of 2017 we will most likely see the complete end-of-life of SHA1 as part of signature suites and we may see an above average increase in modern browser adoption.

Ryan

 

 

Why might you have a certificate with a SHA1 based signature in its chain that is valid beyond 2016/1/1?

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NOTE: Google has updated the plan they will be using to deprecate SHA1 based certificates. The content in this post is still mostly accurate but for dates please see the thread. Personally I think the new plan is a good one. The upsides in this post are still accurate and it is my hope people switch to SHA256 based certificates as quickly as possible.

So there is a plan under discussion to “degrade” the user experience for SSL sessions protected with certificates (or chains) that contain a SHA1 based signature that are valid beyond 2016/1/1.

This 2016/1/1 date was apparently discussed at a CAB Forum meeting six months ago, prior to that the “sunset date” for SHA2 was considered to be 2017/1/1.

Given Chrome represents such a large percentage of the browser ecosystem and they appear to be unwaveringly marching towards this new date I think its fair to refer to this date as the “new sunset date”.

There have been lots of conversations about this topic from the perspective of a CA and that of a browser but not so much from a perspective of a certificate holder.

There are a few cases why you might have such a certificate:

  1. Your certificate was issued before the new sunset date was specified.
  2. When the new sunset date was specified your certificate authority did not update their system to restrict use of that algorithm to expire by that new date.
  3. Your certificate authority gave you the option of choosing which signature suite (and hash algorithm) and expiration dates to use and you chose SHA1.

Some might ask why CAs did not simply stop issuing certificates that utilize SHA1 based signatures all together when Microsoft issued their goal to deprecate by 2017. The answer to this is simple; there is a large number of XP machines out there (15% of the Internet and over 35% of browsers in China) and its unclear how many of them have Service Pack 3 which is necessary to support certificates with SHA2. There are also concerns about the number of mobile and embedded devices that also do not support SHA2.

So how big of a risk is the interoperability impact? It’s hard to say; some numbers i have seen suggest it is less than 1% of traffic but honestly it doesn’t appear possible to measure  the number of XP machines without SP3 and if it were it still wouldn’t take into consideration the devices that do not support SHA2 and we know such devices were shipping as recently as two years ago.

So that takes me to the main reason for this post; it’s my guess that the primary reason you have a certificate that will be effected by this change is that the CAs honestly did not realize google was moving the sunset date forward and were adopting migration plans that they felt balanced interoperability, usability and security.

With that said I believe google sincerely feels this change is in the best interest of the internet and that the user interface changes they are proposing are subtle enough that it wont be noticed by most (see : A Large-Scale Field Study of Browser Security Warning Effectiveness [pdf]).

Unfortunately this leaves you the server administrator stuck somewhat in the middle. You will have to choose to give up views and revenue from these clients that do not support SHA2 or all of your users who use Chrome will see a degraded user experience.

What will Chrome’s SHA1 early warning look like?

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NOTE: Google has since revised its plan to enable a more gradual migration to SHA256, this post is no longer accurate.

For the last few weeks there has been an ongoing discussion on the Chromium security-dev mailing list on how Google intends to implement a user interface change to warn users that a SHA1 certificate is in use.

I wont talk to the reasoning behind this change or to the current and future security properties of SHA1 in this post but I thought some folks might be interested in what this might ultimately look like. I say might because right now there is only a mail thread and who knows how things will evolve and what the copy would be in such user interfaces.

With that said the thread does describe what affordances they intend to use when a site has a certificate where it or the corresponding certificate chain has SHA1 based signature in it (excluding the root) that expires after 2016/1/1 the user interface may be “degraded” for these sessions.

At this time it seems the “red x” that is used for mixed content will be used; if so this will look something like this:

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For the SHA1 certificates that expire after 2017/1/1 if that page contains active content such as JavaScript and CSS that is served over a SSL session with such a certificate they will not be loaded unless the user explicitly chooses to approve their execution, this would look something like this:

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Again for SHA1 certificates that expire after 2017/1/1 if the page contains passive content (such as images) that is served over a SSL session with such a certificate it will not be loaded unless the user chooses to do so and the lock will get a yellow arrow, which will look something like this:

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Which combinations of these things one will see would be dependent on the specific combination of conditions but this will give you some idea on what these changes may look like.

Ryan

Capital One Venture – the card NOT to travel with

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Those of you who know me know that I do a fair bit of travel; in the last year and a half I flew at least 250,000 miles through Asia and Europe for work.

As part of being a regular traveler I wanted a credit card with travel benefits. After doing some research I settled on the Venture Card from Capital One primarily because of its decent interest rate and its competitive points system. With that said I still cannot recommend this as a travel card.

Why you ask? Well there is more to a travel credit card than the interest rate and points. To explain let me tell you about my trip to Russia.

First to be honest I did not explicitly tell any of my cards that I was going to Russia. That said when I know I am going to be a heavy traveler like I was in this time  of my life I will notify any cards (which I did in this case) I intend to use them while traveling that I will essentially be living on the road.

Though it is a good practice to notify your card companies every time you travel internationally calling them every 3 weeks isn’t a reasonable thing to do — and in my defense until this event it was never a problem.

The first part of the trip was in Belarus where almost no one took cards and I ended up paying for everything with cash — even Internet access. The second part of this trip we went to Moscow and the first time I tried to use the Venture card it was denied.

This is the same card I had previously used throughout the rest of Europe and Asia with no problem. Assuming it was an attempt to “protect” me from card fraud I calmly called support reaching what was apparently a Philippines call center where I was instructed that my card had been flagged as stolen by someone in Russia.

I explained this was the first use of the card in Russia and the suspected fraud was me. The agent informed me that despite this fact in the name of my best interests she would be canceling my credit card.

I of course protested; I was after all in another country for another month and had planed to use the points I earned to cover some of the costs of the trip and more importantly I had left my backup travel cards in Belarus. Without this card I was in essence dependent on the limited amount of cash I had left.

I explained my situation to the agent and was told not to worry that she would have a card to me at my home within 24 hours. I explained again that I was in Russia and that sending card to the states wouldn’t be of any use.

The agent then offered to mail me the card in Russia but couldn’t guarantee when it would arrive. I explained that this could take weeks — when I ship items via the fastest choice to Russia they typically get to the country within two days but don’t get delivered for three or more weeks. The agent responded that that this was the best they could offer but after some pushing I managed to get escalated to someone in the US where I hoped I might get a better answer.

It turned out that the US office was closed at that time but a few days later I did get a call back — unfortunately though it was clear this office at least understood the situation (the agent in Philippines office was very poorly trained) I was informed that since the other agent had already canceled my card there was nothing else they could do other than send me a replacement to my home in Seattle.

This is the core of why I wouldn’t recommend Capital One for a travel card — at least to an international traveler; when your traveling your credit card is your safety net, it is how you handle currency conversions, make sure you can feed yourself, have a place to stay and can handle the surprises you may encounter. More than the points, more than the interest rate this is what a travel card is. American Express built its reputation on being that card and when I have had issues in the past they have been there to help – Capital One on the other hand left me stranded.

Anyway I was so dissatisfied with Capital One’s handling of this when I got home I paid off the balance and did not activate the new card they sent.

Fast forward to over 6 months later and I get an email saying they have charged me the renewal fee for this card that in my mind was closed. I was a little disgusted by them charging me a renewal fee for an account they in-essence took from me when I needed it most but I was going to open a card anyway and decided to activate the card they had sent previously and pay the fee.

When I activated the card the automated system told me the card was ready for use but when I tried to use the card the first time it was denied. Frustrated I set the card aside until I had enough time to mess with their support again.

When I called to resolve this I was treated like someone who was avoiding paying a long standing balance and not someone who was trying to just resolve them miss-handling an issue so I just canceled the card.

Long story short — a good travel card has to have good customer service, they have to be your partner and look out for you and Capital One just doesn’t do that.

Though in my new role I don’t do much if any international travel I do a ton of domestic and have been using the Barclay Arrival card. I have had the occasion to talk to their customer service several times, each time they were professional and helpful. While I have not had a similar situation happen while using them as my primary travel card I suspect based on these experiences they would handle things differently.