Category Archives: Security

Safes and Transparency

Lately, I have been thinking about the history of defensive security technology. One of the purest examples here can be found in safes and vaults. The core purpose of a safe is obvious, to make it cost-prohibitive for an attacker to gain access to whatever is inside without being detected.

With that said, the topic is a lot more nuanced than it seems on the surface. If we look at a safe used by a typical community bank in the 1800s, one of the things you will notice is that they often have ornate decorations on their exteriors, beautifully designed locking mechanisms and their locking mechanisms are covered by specific patents. These traits were clearly designed to signal something to the visitors of the bank, namely that they use the latest technology to keep your valuables safe.

Beyond the messaging buried in the design, these safes were also designed to mitigate specific threats, for example, In the mid-1800s it was common for attackers to steal safes, use explosives to open them and to kidnap those that had access to the secrets necessary to open a safe, or those near and dear to them. 

In response to this reality, safe manufacturers started to use materials like manganese to manufacture safes, making the walls very thick and as a result very heavy (often 3 tons or more!), rounding corners, and using locking cylinder-shaped doors in combination to make theft or the use of explosives no longer interesting vectors for an attack.

These changes, combined with artful customizations also provided a way for banks to ensure that sophisticated thieves could not replace a safe in order to delay the detection time and have a safer getaway.

They also started incorporating time locks, to make it so if someone was kidnapped, they would still not be able to open the safe outside core business hours, essentially enabling the creation of a fully disclosed ledger of all goods stored in or withdrawn from the safe.

A famous example here is from 1876 in the robbery of the Great Northfield Minnesota Bank by Jesse James and the Cole Younger gang, it was foiled due to a safe with these design characteristics.

As I think about the parallels in modern technology, I can not help but to come back to a post I did this last year titled “An Evolution of Security Thinking’, in particular how we have gone from security as something you added after the fact to one where it is built into a system from the get-go. Moreover, it seems that these safes may also represent one fo the first examples of transparency being applied as a technique used to dissuade an attacker.

If a safe has no tumbler on the outside, what good would it do to kidnap the bank manager? As a result, the attacker is forced to attempt their theft during business hours when the bank was busy and they would have a larger chance of getting caught.

If it is obvious a safe has 12” thick walls and weighs in at over 3 tons, then stealing the safe at night, or using explosives to open the safe, given the skills and resources of the attacker, is no longer a viable path of compromise either. As a result, forcing the assailant to attack the bank during the day, when the vault may already be opened.

The safe manufactures, by making their designs, and mitigations clear, were attempting to dissuade attackers from even attempting their attack. This is not materially different from how today we are applying the concepts of cryptographic transparency as a tool to mitigate other attacks.

In short, transparent systems are essentially the antithesis of security by obscurity. While designing a system to be cryptographically verifiable does not necessarily require the contents of that system to be known, just as the safe design doesn’t require the contents of the safe itself to be known, the use of these patterns makes it possible to intelligently reason about the security and integrity of the system.

Just a thought…..

P.S. Thanks to Fotis Loukos and Yael Grauer for providing feedback on this post. 

Software Supply Chain Risk Mitigation

Increasingly we are seeing attacks against what is now commonly referred to as the software supply chain.

One of the more notable examples in the last few months was from the Nodejs package management ecosystem [1]. In this case, an attacker convinced the owner of a popular but unmaintained Node package to transfer ownership to them. The attacker than crafted a version of the package that unsuccessfully attacked Copay, a bitcoin wallet platform.

This is just one example of this class of attack, insider attacks of the software supply chain are also becoming more prevalent. When looking at this risk it holistically it is also important to realize that as deployments move to the Cloud the lines between software and services also blur.

Though, not specifically an example of a Cloud deployment issue, in 2015 there was a public story of how some Facebooks employees have the ability to log into users accounts without the target user’s knowledge [2]. This insider risk variant of the supply chain exists in the Cloud in a number of different areas.

Probably the most notable being in the container images provided by their Cloud provider. It is conceivable that a Cloud provider could be compelled by government to build images that would attack a specific or set of customers as part of an investigation, or that an employee would do so under compulsion or in service of personal interests.

This is not a new risk, in fact, management of internal and external dependencies has always been core to building secure systems. What has changed is that in the rush to the Cloud and Open Source users have adopted the tools and resources these cloud providers have built to make this migration easier without fully understanding and managing this risk that they have assumed in doing so.

In response to this reality, Cloud providers are starting to provide tools to help mitigate this risk, some such examples include:

  • Providing audit records of employee access to customer data and services,
  • Building solutions to provide hardware-based trusted execution environments that provide some level of protection from cloud providers.
  • Offering hardware key management solutions provided by third-parties to protect sensitive key material,
  • Cryptographically signing the binaries and images that are published so that their distribution is controlled and tampering post-production can be detected.

Despite these advancements, there is still a long way to go to mitigate these risks in a holistic fashion.

One effort in this area I am actively involved in is in the adoption of the concept of Binary Transparency. This can be thought of as an evolution of legacy code signing models. In these solutions, a publisher places a cryptographic signature using a private key associated with a public certificate of some sort that is either directly trusted based on package origin and signature (such as with GPG signatures) or is authenticated based on the legal identity of the publisher of the package (as is the case with Authenticode).

These solutions, while valuable, help you authenticate a package but they do not provide you the tools to understand the history of that package. As a result, these publishers can produce packages either accidentally or on purpose that are malicious in nature that is signed with their “trusted keys” and it is not detectable until it is too late.

As an example of this risk, you only need to look at RealTek, over the years numerous times their code signing key has been compromised and used to produce malware, some of it targeted such as in the case of Stuxnet [3].

Binary Transparency addresses this risk in a few ways. At its core Binary Transparency can be thought of as an append-only ledger listing of all versions of a given binary, each of these versions having a pointer to a content addressable store where that binary is available.

This design enables the runtime that will execute the binary to do a few things that were not possible, It can, for example, ensure it is running the most recent version of a binary and to only run the binary when it, and some number of previous revisions are publicly discoverable. This also enables the relying parties of the published binaries and images to comp it can inspect all versions and potentially diff those versions to understand the differences.

When this technique is combined with the concept of reproducible builds, as is provided by Go [4] and a community of these append-only logs and auditors of those logs you can get strong assurances that:

  • You are running the same version as everyone else,
  • That the binary you are running is reproducible from the source you can review,
  • The binary are running has not neen modified since it was published,
  • That you, and others, will not run binaries or images that have not been made publicly available for inspection.

A system with these properties disincentivizes the attacker from executing these attacks as it significantly increases the probability of being caught and helps bound the impact of any compromise.

Importantly, by doing these things, it makes it possible to increase the trust in the Cloud offering because it minimizes the amount of trust the user must put into the Cloud provider to remain honest.

A recent project that implements these concepts is the Go Module Transparency project [5] [6].

Over time we will see these same techniques applied to other areas [7] [8] of the software supply chain, and with that trend, users of open source packages, automatic update systems, and the Cloud will be able to have increased peace of mind that their external dependencies are truly delivering on their promises.


  • [1] Node.js Event-Stream Hack Exposes Supply Chain Security Risks
  • [2] Facebook Engineers Can Access Your Account Without A Password
  • [3] STUXNET Malware Targets SCADA Systems
  • [4] REPRODUCING GO BINARIES BYTE-BY-BYTE
  • [5] Proposal: Secure the Public Go Module Ecosystem
  • [6] Transparent Logs for Skeptical Clients
  • [7] Firefox Security/Binary Transparency
  • [8] Contour: A Practical System for Binary Transparency

Secure, Privacy Preserving Key Discovery for End-To-End Encryption

A lot of products today claim to offer End-To-End Encryption but not all of these products offer the same level of protection. Some of the differences between these solutions are rooted in the protocols and cryptography that they use, in some, it is in the way they are implemented and in others it is the way they handle the discovery of the cryptographic keys of the peers involved in the session.

The topic of key discovery itself is a complicated one, on its surface, for a messaging application all you need to do is go to a directory to request the public key pairs associated with the user or their devices you will communicate with. Where things get tricky is how, as a relying party, you can tell if the key discovery mechanism is lying to you or not.

This is important because if the key discovery server is lying to you it can facilitate an impersonation of that user, add a hidden third-party to the encrypted session without your knowledge, or potentially trigger a re-encryption to a device not under your control without your knowledge.

To understand the implications here you just need to look at iMessage. Although many do not know this iMessage is actually End-to-End Encrypted! Matthew Green has done several great write-ups on its protocol [1] [2] and how the lack of verifiability in the key discovery mechanism utilized weakens the overall solution.

The most used End-to-End Encrypted messaging application is probably Facebook’s What’s App. Several years ago a security researcher [3] reached out to The Guardian to discuss what they described as a “backdoor” in What’s App, this “backdoor” was related to how it handled key discovery in device recovery use cases.

As a product person, you often need to make trade-offs to achieve your goals and that was what happened in this case. This “backdoor” was a design decision that was made to ensure billions of users could get some of the End-to-End encryption protections without compromising usability.

A number of security researchers, including myself, spoke up [4] which resulted in the article being updated to correctly reflect this reality [5] flawed reporting about WhatsApp.

Later WhatsApp and how Key Discovery happens came up in the news again, this time in an article from Wired [6. Alex Stamos, the former Chief Security Officer of Facebook, responded to this article [7] affirming some of the article’s points and talking about how a conscious decision was made to enable the associated use case:

“Read the Wired article today about WhatsApp – scary headline! But there is no secret way into WhatsApp groups chats. The article makes a few key points.”

While is response may be true, it is nor verifiably true as it relies on the behavior of the client and not cryptographic verifiability.

This is where systems like CONiKS [8], Keybase [9] and Google’s Key Transparency [10] come into play.

These solutions aim to enable automated trust establishment with untrusted communication through the use of an auditable directory of all of its users’ keys both past and present.

The fact that these solutions provide the auditable history of keys means that both the relying party and subscriber involved in the communication can reliably be made aware of when new keys have been associated with a users account, and importantly what entity added the key to the account.

With this information, they applications the users are using can both prevent messagings (via policy) being sent or notify the user when keys have changed unexpectedly.

This allows messaging clients to verify the identity of users automatically and prevents malicious/compromised servers from hijacking secure communications without getting caught.

On the surface, this sounds much easier than it is to acomplish at least at scale. WhatsApp serves over a billion users, any solution needs to be able to deal with key updates and reads at rates necessary to support such a large user base.

It needs to do this without leaking metadata associated with who the users are communicating with.

And do this without significantly increasing the amount of data a user must download or the time it takes to change keys.

While these are all tractable problems, they are not problems that are solved today in this context.

For this reason, applications that implement End-To-End Encryption typically either provide a mechanism that users who care about these risks can use to out of band verify cryptographic keys in person [11] or simply implicitly trust the key discovery service as an honest actor.

At Google, I have the pleasure of working on Google’s answer to this problem [12]. It is our hope that when complete that applications that need to securely discover keys in a verifiable way can simply download our solution and focus on their application and not need to spend years of energy to solve this problem for their applications.

I firmly believe the best way to ensure the right thing happens is to make sure that the right way is the easy way and fundamentally that is the goal for the Google Key Transparency effort.


  • [1] Attack of the Week: Apple iMessage
  • [2] Let’s talk about iMessage (again)
  • [3] The Guardian is backtracking on a controversial story about WhatsApp
  • [4] Security researchers call for Guardian to retract false WhatsApp “backdoor” story
  • [5] Flawed reporting about WhatsApp
  • [7] Read the Wired article today about WhatsApp – scary headline!
  • [8] CONIKS Project
  • [9] OKCUPID’S FOUNDERS WANT TO BRING ENCRYPTED EMAIL TO THE MASSES
  • [10] Google’s Key Transparency project aims to ease a tough task in cryptography)
  • [11] Safety number updates

What is Fortify and how does it work?

If you follow the W3C or web development, you probably know that the WebCrypto API was designed to provide fairly low-level cryptographic algorithms so that you could build web applications that interoperate with existing systems.

The idea being it was largely the cryptographic primitives that needed to be implemented natively and that the other layers of interoperability could be handled in pure Javascript when combined with good application security practices and new features like SRI.

While there are legitimate concerns over the use of cryptography in browser-based applications there are also legitimate uses. Afterall who doesn’t like to watch a film on Netflix now and again without having to run Flash?

For another example of an application that makes heavy use of WebCrypto take a look at 1Password which is one of the most popular password managers in use today. They use WebCrypto and the same origin security model of browsers to allow them to help manage their passwords locally and store the associated ciphertext on their servers.

The utility of WebCrypto does not end with applications though, many libraries, some by my company, Peculiar Ventures, leverage this raw cryptographic capability to make it easier for others to build applications that interoperate with their counterparts on other platforms. For example consider PKIjsXMLDSIG, XADESjs, 2key-ratchet and js-jose.

However powerful this new native cryptographic capability is, it intentionally left out providing access to local cryptographic certificates and key stores as well opted out of providing web applications access to smart cards and other security elements. I personally both agree with these decisions and understand why they were made but that is something for another post. With that said, that doesn’t mean those capabilities are not useful and that is where Fortify comes in.

So what is Fortify?

Fortify is a client application that you install that runs in the background as a tray application in Windows, OSX, and Linux that provides these missing capabilities to authorized applications.

It does this by binding to 127.0.0.1 and listening to a high-order well-known port for incoming requests. Browsers allow web applications to initiate sessions to this address, over that session a Fortify enabled application establishes a secure session and if approved by the user is allowed to access these missing capabilities.

How is this secure session established?

At the core of Fortify is a library called 2key-ratchet. This implements a `Double Ratchet` protocol similar to what is used by Signal. In this protocol each peer has an identity key pair, we use the public keys from each participant to compute a short numeric value since in the protocol the peers prove control of the respective private keys we know that once the keys are authenticated we are talking to the same “identity”.

Since 2key-ratchet uses WebCrypto we leverage the fact that keys generated in a web application are bound to the same origin, we also (when possible) utilize non-exportable keys to mitigate the risks of these approved keys from being stolen.

This gives us an origin bound identity for the web application that the Fortify client uses as the principal in an Access Control List. This means if you visit a new site (a new origin), even if operated by the same organization, you will need to approve their access to use Fortify.

For good measure (and browser compatibility) this exchange is also performed over a TLS session. At installation time a local CA is created, this CA is used to create an SSL certificate for 127.0.0.1. The private key of the CA is then deleted once the SSL certificate is created and the Root CA of the certificate chain is installed as a locally trusted CA. This prevents the CA from being abused to issue certificates for other origins.

What happens over this session?

The protocol used by Fortify use a /.wellknown/ (not yet registered) location for capability discovery. The core protocol itself is Protobuf based.

We call this protocol webcrypto-socket. You can think of the protocol as a Remote Procedure Call or (RPC) to the local cryptographic and certificate implementations in your operating system.

Architecturally what does the client look like?

The Fortify client is a Node.js application based on Electron and it accesses all cryptographic implementations via node-webcrypto-p11. This library was designed to provide a WebCrypto compatible API to Node.js applications but it also extends the WebCrypto API to provide basic access to certificate stores.

The Fortify client uses another Peculiar Ventures project called PVPKCS11 to access the OSX KeyStore, Mozilla NSS or Windows CryptoAPI via this PKCS#11 wrapper.

It also uses pcsclite to listen for a smart card or security token insertions and removals, when new insertions are detected it inspects the ATR of the card. If it is a known card the client attempts to load the PKCS#11 library associated with the card. If that succeeds events in the `webcrypto-socket` protocol are used to let the web application know about the availability of the new cryptographic and certificate provider.

Ironically, despite the complication of the PKCS#11 API, this approach enables the code to maintain a fairly easy to understand structure.

The application also includes a tray application that is used to help with debugging, access a test application and manage which domains can access the service.

So what can I do with it?

In the simplest case, you can think of Fortify as a replacement for the <keygen> tag.

Since the client SDK that implements the `webcrypto-socket` protocol is a superset of WebCrypto, with slight modifications, if you have an web application that uses WebCrypto you can also use locally enrolled certificates and/or smart cards.

Some of the scenarios we had in mind when building the Fortify client included:

— Enrolling for X.509 certificates over the web,

— Signing and encrypting/decrypting email or documents,

— Building certificate-based authentication schemes with a modern user experience.

Can I use this today?

Yes, it is feature complete and ready for you to take a look.

There are some examples on its usage here and you can find the documentation here.

It works on Windows 7+, OSX 10.12+, and Debian based Linux distributions, it also works on IE11, Edge, Safari, Chrome, and Firefox.

In general, you should consider this initial release of a Beta quality, for example I know we need to do additional testing with smart cards and make sure we have the metadata for each card so they work on each supported platform. Otherwise, we expect it to work largely as expected.

Is it Open Source?

Yes, all Peculiar Ventures related libraries to-date have been licensed as BSD or MIT and this is no different so you are free to do with them as you see fit.

What’s next?

Over the next year, we will gain enough confidence in the solution to declare it complete. We will also look at adding other useful like smart card password changes and unblocking at some point in the future.

Other than that, we are just looking for your feedback so we can refine the quality of the solution.

Thanks

I want to thank the members of the CASC for their support of this project and the many individuals from Twitter who provided feedback and testing.

What value can a third-party provide users when browsing the web?

While at the CA/Browser Forum I was asked by a friend if we wanted to replace EV with a new class of certificate what would that certificate look like?

My response was that I would frame the question differently. The “real” question is what problems does a typical user have that a third-party with the strengths of a CA could help with?

With this in mind, you need to first understand who this stereotypical user is, a software engineer may have different needs than a grocery store clerk. They may also have common needs, you won’t know that until you do research.

The only way to do reliable research on this topic is to actually work with those users to understand what their needs are. While this is much harder than it sounds due to biases introduced in such processes a real needs analysis requires that you start here.

With that said, I suspect this exercise would show a broad swath of the target users is concerned with these questions:

  • Will I have a good experience working with the people behind the website?
  • Do the people behind this website have a good reputation?
  • Are the people behind this website experts in their craft?
  • How do I figure out how to reach a real human when and if I need to?

I would put those concerns into the context of the interaction they will have with the website (buying a product, downloading software, etc).

With that understanding I would then try to understand what the strengths of the CA are, having been a CA for a long time I would say:

CAs are good at verifying claims relating to the subject of a certificate.

I would then try to map the identified problems and strengths together to see what potential value the CA could provide that user.

Again the right thing to do is formally do those above explorations but for the purpose of this post I suspect these exercises would find that:

  • When a user visits a website they may struggle to find out how to contact the sales/support for that business,
  • When a user visits a site for the first time it may be hard for them to determine what the companies true line of business is,
  • After a user previously visited a website and completed a transaction with it they sometimes need to contact that business after the fact and could be assisted in finding the right contact information,
  • Before deciding to do a high-value transaction with a business, customers may want to find out the experience others have had with that business.

Now, just because a user may have these problems and a CA may be able to help solve them, it does not mean the SSL indicator is the right place to help answer these questions. It just means that there is a problem and skills intersection.

When, and how to solve this problem is another exercise altogether. Let’s explore EV for a second to give that some context.

Today if we assume the information in an EV certificate is correct (and not confusing see: this and this for context) we can say it provides the answer to “if I need to sue these people where do I tell my lawyer they are at?”.

The problem with that is that you may not have that information when you need it. I say this because you typically need to sue someone after you completed a transaction with them not before. After the fact, you have no assurance that this information in the certificate will be available at the site you did the transaction with.  The website may have gone away, they could have changed their certificate, or could some other change may have taken place that makes that information not readily available to you when you need it.

In any event, the point of this post is to say CAs should not be asking what they can put into certificates but what problems users have that CAs are well suited to solve. Unless they start there they will not be solving a real problem, they will just be bolting more things onto a certificate and asking why browsers and users don’t users see value in it.

Reality vs Fantasy – The DV vs EV argument

This morning I woke up to a blog post from Melih, the founder of Comodo titled “Problem vs Solution Value mapping”.

This is a follow-up to an ongoing discussion Melih and I have been having about the value of EV, and positive trust indicators. On my blog, the conversation started July 2017 if you’re interested.

Melih’s focuses his most recent post on the assessment of “value”, correctly attempting to define it as the basis of the rest of the post. He chooses to define it as  “the direct result of a resolution to a problem.” I think it is this definition is the first part of his argument I have an issue with. Namely, The Oxford Dictionary defines “value” as “the regard that something is held to deserve; the importance, worth, or usefulness of something.”

When considering “value” with this definition, I believe an analysis of “value” would start by building a case on what is “deserved”. To do that, we have to also define a context in which that value is assessed. I think this is probably the hardest part, and probably where most of the disagreement on “value” of EV stems from.

If we say the context of this assessment is “the security and privacy guarantees that can be provided to the user by user agents to users” EV’s value is no better than that of DV. It is not a hard case to make either.

The security model of the browser is based on the concept of “origin” where that origin is essentially the “hostname” that the content was retrieved from. Any external website or resource embedded in the site (with rare exception) has the same permission as the original website as a result of this model. This is how web analytics work, advertising and many other products and services that make up the web.

Until user agents required all of these entities that make up a given site to use EV and to have the legal entity in all of the associated certificates match; EV is a false flag. It says “you are talking to this legal entity” when in-fact your talking to many legal entities and any one of them could equally harm you.

The reality is that if this change were to be made that you would almost never see EV badges though. This is because virtually every site is made up of content and services from across the web and this condition would almost never be met. This is why we do not see CAs making the argument that this rule should be enforced by UAs.

If we say the context of this assessment is “the average users practical ability to protect themselves from phishing” again EV does not fair well. There have been lots of user studies done on how users do not understand positive trust indicators, and in general, do even notice them in most cases.

Furthermore, even if we disregard these well-run studies (and the associated common sense) as Ian Carroll showed with his Stripe, Inc business in Kentucky the values displayed in these indicators can trivially be made, at a very low cost and with no traceability, be made to say whatever an attacker wants. This again frames EV as a false flag because it can so easily be used to lend credence to a phisher’s site by giving them the EV badge that says the same thing as their target site.

If this was not enough, again if we disregard these well-run studies and say that people need to take the responsibility for looking at the EV badge to get confidence they are dealing with a trustworthy entity we need to look no further than the work James Burton did when he got a certificate for his business “Identity Verified”.  In this case, if a user has been taught to look at the EV indicator for an abstract concept of “trustworthiness” we are back to the user being mislead.

All of this ignores another very real problem, that being most phishing sites are not bespoke sites, instead, they are sites that are hacked and re-purposed. A good example of this is this one from a few weeks ago. What we appear to have here is a company called Northern Computer Services, LLC hosting a website for a business with the domain name “stampsbyjudith.com” hosting a Bank of America phishing site.

Now EV proponents surely see this as an example of EV working but if you look at it critically you will see it is exactly the opposite. First, could a customer believe that this “Northern Computer Services” is somehow a service provider to Bank of America? It seems reasonable to assume that the average user does not know anything about the way Bank Of America operates its services. In-fact even if you do have some level of understanding it’s incredibly common for banks to use service providers for different capabilities, maybe this Northern Computer Services hosts the BoFa website or provide billpay or mortgage services. How is the average user to know?

But what about the URL? There is no plausible way Bank Of America is hosting their site on the domain stampsbyjudith.com! Your absolutely right! it’s a fair expectation of us that if a user happens to look at the address bar that they should be able to figure that out. This is of course something you get when you use DV though, no EV necessary. Then there is the issue that studies also show that users do not look at the address bar either.

This is why Microsoft has created SmartScreen and Google has created Safe Browsing. These solutions utilize the massive scale and technology depth of these organizations along with machine learning and other advanced techniques to find phishing sites. As a result when a user navigates to a site similar to this one they get a interstitial warning them about proceeding.

In summary, in this context, I would argue that as EV exists today it actually makes things harder on the user and easier on the attacker.

With that context in mind let’s explore each of the arguments that Melih makes.

Users want protection from Transit Providers. Sure they do but I would say the if a user framed the topic this way it would demonstrate the how little they actually understand of the problem in question. It is not just “transit providers” they need protection from, it is every entity other than those that are necessary to serve the application hosted at a domain.

Networking is so complex it is not possible to expect even some of the most technical users to understand all of the nuances involved here.

I would like to point out that Melih again attempts to redefine terms, this time in a disingenuous way. Specifically, in this part of his post suggest there is some common understanding that there is a difference between “encipherment” and “encryption”.

Let’s again take a look at what the Oxford Dictionary says:

Encryption – The process of converting information or data into a code, especially to prevent unauthorized access.

Encipherment – Convert (a message or piece of text) into a coded form.

As you can see, these words mean the same thing. The only difference being the example use case in one of the definitions. But maybe this inconsistency is use  is because the Oxford Dictionary does not address a cryptographers view on these words? Unfortunately, that is not the case either, if you were to look at books like Serious Cryptography, Cryptography and Network Security, or even the very dated Applied Cryptography you will find no usage of these terms in this way.

What Melih has suggested in the past, and continues to do so in this section is that somehow if you authenticate only the domain and use that authentication as the basis for the session protection that this is not “encryption”.

Going so far to suggest that it is only encryption if you authenticate the legal entity. This is frankly ludicrous and I can not even respond to this more than I just have here.

I can say, that redefining a term, especially in such a specious way devalues any other valid points he may have.

But what about the users! The users want to know who they are dealing with! I actually agree with this but I also think it is far more complicated than users actually understand. So much so I would argue it is not possible to do in most cases. As a father when I run into situations where my kids want things that are not possible I sometimes joke with them and say “Well I want a pony!”.

It feels to me this is probably a case where that response is appropriate. The reality is there is not a globally unique business name, this is also the case with logos. Probably the best mainstream examples of this are the fake Starbucks stores and the notorial “Apple Stores” of Asia.

Fake Apple Store Highlights Counterfeit China

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This is the nature of brand names, in-fact there is an entire discipline of law (Trademark Law) dedicated to this topic and multilateral international agreements on how such disputes are to be handled.

So in the context of the url, does EV as it stands today add or remove value? From my perspective, it seems to me at a minimum in this context it provides no value but I could also make a reasonable argument it makes things worse here as well due to the introduction of more surface area for confusion.

User’s want to know if its “safe” to interact with the website! Again I can agree with this, the problem is names do not harm — we even teach our kids rhymes to remind them of this fact:

Sticks and stones may break my bones, but names can never hurt me.

To keep users safe we have to look at far more than the name a website is hosted under; there are literally thousands of features that a solution intending to protect users safety need to consider and I would not be surprised to find out that the name is one of the least important.

This is, again, why we have solutions like SmartScreen and Safe Browsing these solutions are constantly watching feeds of data to determine if a website is safe or not. It is not possible to solve the “safety” problem in any meaningful way without similar techniques.

But user’s want to be able to trust the content they see! Again, I also think this is something that users want, I just don’t think they can have everything they want.

But before I talk about this I want to talk about how Melih is redefining a term again, he suggests that “trust” means “having the ability to validate VISA, Paypal logo etc”. The oxford dictionary defines trust as “Firm belief in the reliability, truth, or ability of someone or something.”

With that, I would think that it would be more correct to say that they want to believe what they see. This is of course a very natural thing, something scammers have taken advantage of since the dawn of time.

When considering this desire I think we have to ask ourselves what the best way we have to service the desire. We also have to acknowledge that malicious content is everywhere in the world (don’t forget our Fake Starbucks and Apple Stores from above) that the best we can do is provide a speedbump.

This is, again, why we have solutions like SmartScreen and Safe Browsing as they were designed, engineered and continually evolve to address these risks.

In closing, I believe EV as it stands today is a round peg in a square hole. This does not mean there is not value in knowing the legal identity of the organization who operates a website, it is also not because these third-parties can’t do more to help users manage the risks they are exposed to.

It is because EV is being sold as something it is not, a anti-phishing tool. Simply put it is not well suited to help with that problem and I would go so far that when we teach users to see it as such it even helps phishers.

Risk variance and managing risk

One of my favorite security sayings is “My threat model is not your threat model”. We broadly accept there are different perspectives for every problem — the same is true with security.

Consider an Enterprises IT organization where you are chartered to support and secure a business. You need to meet this charter with a fairly fixed set of resources but the business requirements you must support are always changing. To deliver a reasonable level of service enterprises standardize on a core set of ways that certain issues (user and access management, compute, etc.) will be provided and force business units down the path of adopting them.  But that standardization often results in non-ideal user experiences, disjointed business workflows, slow innovation and importantly, in this case, it also commonly results in the either over or under mitigating security risks.

Startups, who are on the other end of the spectrum, are in a race to demonstrate market traction before their funding runs out. As a result, startups either virtually ignore security and privacy altogether or re-using a component they do not understand that is not well suited to the business problem they are solving or simply solves the wrong problems for their business risks.

Both enterprises and startups show the hard reality that we are often so close to our problems and set in our way of thinking we simply miss the big picture. This natural bias can hurt our businesses and in the context of security trade-offs, and result in incidents like the recent Equifax breach or the ever-growing list of Bitcoin exchange compromises.

The first step in preventing this “missizing” of risk is to make sure you understand what your risks actually are. The right way to do that is to think adversarially, taking a step outside of your business process or solution and thinking about the structure of the system your protecting and defining a threat model that captures those risks. This is not a one time exercise, it is something you need to constantly be re-visiting and getting new perspectives into.

Consider the typical Bitcoin exchange compromise, the exchanges usually start with a basic system limited to “online hot wallets” with weak architectural protections. They probably know better (for humanity’s sake I hope they do) but decided that the risk, in the beginning, is low enough because they have so little to lose that they go forward. Later they find success and are focused on other parts of their business and never get back to fixing that early trade-off.

As an aside, this bitcoin example showcases lots of problems, the largest being the asymmetric risk distribution. Specifically, the risk here is that of the depositor but the decision to take the risk is made by the exchange. I digress but this class of problem is a real problem in most startups and is the impact of which is multiplied 1000x in Bitcoin startups.

In any event, we can see how these sorts of things happen in hindsight so how can we limit how often these issues happen in the first place? As a technologist it hurts me to say this, the answer is process.

The good news is that process does not need to be heavy-weight. You need to make sure you approach the problem systematically and regularly, for example:

  • Instead of a threat model, you can do a simple threat tree,
  • You can use your bug tracking system to track the security issues you have found,
    • You can make sure those bugs capture the security decisions you have made,
    • The consequences of the identified risks for the actors in the system are captured,
    • What mitigations you have put in place for those issues along with how effective you think they will be are captured,
  • And importantly have a plan for how you will respond when things go wrong because they will regardless of how well you plan and invest in making the right security decisions.

You can then make sure you are reviewing these and acting accordingly on a regular schedule. This will ensure your organization at least has an inventory of issues that can last the individuals on a team and will make sure there is a point of conscious risk acceptance that the organization has taken.

This does not replace a full-on security program but it can at least make sure you are looking at the problem in the context of your business, your users and not just assuming every system has the same security needs.

On a related note for you startups, especially those who are operating in murky waters regarding regulation. The current regulations belong in your threat tree so you can make sure you understand them and begin to understand how they might apply to you even if you have to squint a bit to do it.

The Evolution of Security Thinking

In design sometimes we refer to the strategies used during the design process as Design thinking.  The application of these strategies helps ensure you are solving the right problems and doing so in a repeatable way. You can attribute much of the massive improvements in usability in software and devices over the two decades to these strategies.

If we look at how we have evolved thinking around building secure systems over the last two decades we can see that we have evolved similar strategies to help ensure positive security outcomes.

If we go back to the late 80s we see systems that were largely designed for a world of honest actors. There was little real business happening on the Internet at the time and the hard problems to be solved were all related to how do we enable a global network of interconnected systems so thats where efforts were put. These efforts led us to the Internet of today but it also gave us systems vulnerable to trivial attacks such as the Morris Worm.

By the 90s the modern “security industry” was born and products designed to protect these insecure systems from the internet started to come to market. One of the most impactful examples of this was the TIS Firewall Toolkit, other examples of this way of thinking include Antivirus products and other agents that promised to keep our applications and operating systems safe from “attackers”.

By the late 90s and early 2000s, it was clear that these agents were never going to be effective at keeping the bad guys out and that we needed to be building systems that were Secure by Default, Secure by Design and Private by Design. This shift in thinking meant that solution developers needed to develop their own strategies and tooling to ensure systems could be built to be inherently resilient to the risks they were exposed to. The concept of Threat Modeling is probably the most concrete example of this, believe it or not, this basic concept was essentially absent from software development up until this point.

By this time the technical debt in deployed systems was so great we spent most of a decade just trying to rectify the mistakes of the past. Windows XP SP2 and the Microsoft Security Stand Down is probably the most visible example of the industry making this shift, it also leads to the Security Development Lifecycle that largely informs how we as an industry, approach building secure systems today.

During this timeline, cryptography was treated as something that you sprinkled on top of existing systems with the hope to make them more confidential and secure. As an industry, we largely relied on the US Government to define the algorithms we used and to tell us how to use them securely. As a general rule only products designed for government use or for the small group of “cypherpunks” even considered the inclusion of cryptography due to the complexity of “getting it right”.

Things are changing again, we see the IETF via the CFRG working to standardize on international and independently created and cryptographic algorithms in lieu of relying exclusively on governments to do this standardization. We also see the concept of Formal Verification being applied to cryptographic systems (Galois is doing great work here with Cryptol as are other great projects in the verifiable computing space) which is leading us to have frameworks we can apply to build these concepts into other products securely (check out the Noise Protocol Framework as an example).

I think the Signal Protocol, Rough time, Certificate Transparency and even Blockchain Technologies are examples of the next phase of evolution in our thinking about how we build secure systems. Not because of “decentralization” or some anti-government bent in technologists, instead, these systems were designed with a more-complete understanding of security risks associated with their use.

Trust is a necessary component of human existence. It can give us peace of mind but It can also give us broken hearts. The same is true in the context of system design. Trust cautiously.

These systems, by design, go to great length to limit the need for “trust” for a system to work as intended. They do this by minimizing the dependencies that a system takes in its design, this is because each of those dependencies represents an attack vector as we advance technology our attackers become more advanced as well. They also make extensive use of cryptography to make that possible.

This focus on dependency reduction is why we see Blockchain enthusiasts taking the maximalist position of “Decentralize all the Things”. In my opinion, centralization is not always a bad thing, over-centralization maybe, but centralization can provide value to users and that value is what we should be focused on as solution developers.

My personal take is that when we look back on the next decade we will the say the trend was not “blockchain” but instead this is when we evolved our security thinking and tooling to better utilize cryptography. Specifically that this is when we started to use cryptography to make transparency, confidentiality and verifiability part of the core of the solutions we build instead of thinking of it as a layer we apply once we are done.

Positive Trust Indicators and SSL

[Full disclosure I work at Google, I do not speak for the Chrome team, and more generically am not speaking for my employer in this or any of my posts here]

Recently Melih did a blog post on the topic of browser trust indicators. In this post he makes the argument that DV certificates should not receive any positive indicator in the browser user interface.

I agree with him, just not for the same reasons. Positive trust indicators largely do not work and usability studies prove that is true. Browsers introduced the “lock” user interface indicator as part of a set of incentives and initiatives intending to encourage site operators to adopt SSL.

What is important is that these efforts to encrypt the web are actually working, over half the web is now encrypted and more importantly the adoption rate is demonstrating hockey stick growth.

As a result, in 2014 Chrome started down the path of deprecating positive trust indicators all together. In-fact today Chrome already marks HTTP pages as “Not secure” if they have password or credit card fields.

The eventual goal being able to mark all HTTP pages as insecure but for this to happen SSL adoption needs to be much higher, I suspect browsers will want to see adoption in the 90% to 95% range before they are willing to make this change.

This is relevant in this case because if all pages are encrypted what value does a positive trust indicator have? None. This means that when all HTTP pages get marked “Not secure” we will probably see the lock icon disappear.

So, as I said, I agree with Mehli, the “Secure” indicator should go away but so should the lock, the question is not if, but when.

But what does that mean for EV trust indicators? I am a member of a small group, a group that thinks that EV certificates can provide value. With that said today EV certificates have some major shortcomings wich significantly limit their value, some of which include:

  • It is not possible to get an EV wildcard certificate,
  • CAs, largely, have ignored automation for EV certificates,
  • Due to the lack of automation EV certificates are long lived and their keys more susceptible to theft as a result,
  • The vetting processes used in the issuance of EV certificates are largely manual making them expensive and impractical to use in many cases,
  • CAs market them as an antiphishing tool when there are no credible studies that support that,
  • The business name in the certificate is based on the legal name of the entity, not the name they do business under (DBA),
  • The business address details in the certificate are based on where business is registered (e.g. Delaware),
  • There is no contact information in the certificate, short of the taxation address, that a user can use to reach someone in case of an issue.

Addressing these issues have either been actively been resisted by CAs, for example, DigiCert has tried to get EV wildcard certificates to be a thing in the CA/Browser Forum a number of times but CAs have voted against it every time, or simply ignored.

There are some people who are working towards addressing these gaps, for example, the folks over at CertSimple but without CAs taking a leading role in redefining the EV certificate the whole body of issues can nott be resolved. Importantly until that happens you won’t see browsers even considering updates to the EV UI.

Given this reality, browsers have slowly been minimizing the details shown in EV certificates since they can give users the wrong impression and have limited value given the contents of the certificate.

It is my belief that unless the CAs work together to address the above systematic issues in EV certificates that minimization will continue and when the web is “encrypted” it won’t just be DV that loses its positive trust indicator, it will be EV also.

 

Let’s talk about revocation checking, let’s talk about you and me.

I have been having a conversation with Melhi at Comodo, this is the most recent post in that series.

First of all, the author is unaware that my company has built the most sophisticated Certificate Management system that can automatically request, issue, renew and manage the whole lifecycle of the certificate. Many Fortune 500 companies rely on this amazing technology to manage their PKI infrastructure.

I am aware.

So it is with that expertise and insight I must insist that the author does not appreciate the nuance between “high frequency” renewal vs “low frequency” renewals. Short lived certs will require “high frequency” renewal system. To an IT admin this is a scary prospect! They tell us that!

Having been responsible for and or worked heavly on:

  • The Valicert OCSP responder and clients,
  • The Windows CA and the enrollment client at Microsoft, which is the most used CA software ever,
  • The Network Access Protection solution that used IPSEC and ~12-hour certificates to do segmentation of hosts at the IP layer and their health. based network isolation solution that was deployed into many of the Fortune 500,
  • All of GlobalSign’s technology offerings, in particular, the technology enabling their expansion into the Enterprise,
  • Helping the ISRG build out Let’s Encrypt,
  • Designing, building and operating numerous other high volume products and services in finance, healthcare, and government.

Above and beyond that I helped secure Bing Ads and Live ID and now work at Google on other very high scale systems.

Needless to say, I too have familiarity with “high frequency”,  “low frequency”, “disaster recovery” and “availability” problems.

As for fear, it is a natural part of life, I believe it was Nelson Mandela who famously said: Courage is not the absence of fear but the triumph over it.

The reality is that it is manual certificate lifecycle management that is the thing to be afraid of. That is why COMODO and other CAs have been building out cloud-based management and automation solutions over the last few years. For customers this reduces failure, reduces costs, gives more control, and nets higher customer satisfaction.

Importantly, one needs to remember it is manual processes that lead to the majority of outages [see 1,2,3, and 4]. The scale of this problem has even led to an entire market segment dedicated to managing the lifecycle of WebPKI certificates.

So to the question of fear, I would say the same thing my father told me, though change can be scary and uncomfortable in the short term, it usually turns out okay in the end, and often better.

I believe there can be a scalable revocation infrastructure that can serve status for all certs from all CAs that is backward compatible with existing issued certificates that can be called from a browser. As I said before I do believe in the ingenuity of our scientist and engineers to bring us this solution……soon….

You misunderstand me. I did not say it was impossible to have a scalable revocation infrastructure that is backward compatible. I said the creation of a new system that could deliver on the small message size promise we were discussing would take 10 years to design, build and deploy.

To understand my rational take a look at this post. It is a little old now, and update rates are a faster now but not massively. When you review it you will see that if you exclude IE/Edge it takes just under a year for a new version of the most common browsers to reach 90% market share.

To put that in a more concrete way, if today, Chrome, Firefox, and Safari decided to simultaneously release a new version with a new revocation scheme it would take a bit less than a year for us to see 90% deployment. That is, of course, an unrealistic goal. Apple, for example only releases new versions a few times a year and does not even support WebRTC yet. Additionally, browsers have a pretty deep-seated position on revocation checking at this point given all the problems of the past so convince them will take time.

A more realistic, but still optimistic period assuming pre-existing consensus and a will to solve the problem is 5 to 6 years. If you question this figure, just look at how long it took for TLS 1.2 to get deployed. TLS 1.2 was published in 2008 and was not enabled by default in Windows until Windows 8.1 in 2014.

Web servers are even worse, as an example consider Apache version 2 was released in 2002 and these later versions still have less than 50% deployment.

Lets call it DCSP 😉

DCSP isn’t a bad idea, but it has its own challenges. For example, some that come at the top of mind are:

  • Most browsers do not ship their own DNS clients, this is one of the problems DNSSEC had in deployment. If the operating system DNS APIs they use do not provide the information they need then they can not adopt any technology depend on it.
  • Middleboxes and captive networks make DNS-based distribution problematic. Again DNSSEC suffered from this.
  • If DCSP requires a custom record type, for example, DNS servers and tooling will need to be updated. DNS servers also do not get updated regularly, this is another thing that has held back DNSSEC as well as CAA. It is fair to say that it is fair for the WebPKI CAs to update their DNS but based on the glacial pace in which CAs adopt technology that is 3-4 years before you could see deployment even with that (see CT as an example).

To be clear, I think something like this is worth exploring but I don’t think it will see meaningful deployment in the near term.

If we were in Vegas, I would say the most expedient path is to build on what is there, while in parallel building the new thing. This can shave as much as 5 years off the time it takes to solve the problem. If nothing else this moves the CA ecosystem closer to an operational maturity capable of supporting the new system.

Ryan