Security By Buzzword – Why I don’t support Ensafer

Update: I had a call with Ensafer’s CTO, Trygve Hardersen to discuss the issues I brought up, and what they can do about it. First, they updated the site so that downloads are now over HTTPS. He stated that the infrastructure that powers their service is separate from the website, and everything is over HTTPS. They are working on making documentation available, and hope to have the first documents available soon. Once I get a chance to look over their documentation, I’ll post further updates.

Ensafer is an overlay to Dropbox that offers end-to-end encryption, the goal being to address privacy concerns that Dropbox can access user’s files – and thus possibly the US Government (via NSLs, etc.). This sounds like a great idea – end to end encryption is the best way to prevent unjustified surveillance, and I do use a competing product (Boxcryptor), so I support the concept, but what about Ensafer’s implementation – does it provide the level of security desired?

Where are the details? #

If you look at Ensafer’s site, you’ll find precious few details on what they are doing – plenty of security buzzwords, but no specifics. Let’s take a look at the one page with details:

Ensafer believes in standards and we don’t use any custom encryption algorithms. Our encryption platform is built on:
2048-bit RSA keys
256-bit AES encryption
2048-bit SSL
PKCS#12 key containers
X.509 certificates

We see some algorithm names – but what about key derivation, or symmetric encryption modes? How about hashing algorithms? How and where is your password stored? There are so many implementation details that are critical for security, yet aren’t talked about at all.

In December of 2012 I started asking about details, they pointed me back to the web site – when I pushed for more, I was told that they were working on a whitepaper to explain their implementation:

@adamcaudill We have not published all technical details, but we're working on a whitepaper which will be published later. ^LS
— Ensafer (@Ensafer) December 3, 2012

More than a year later, I’m still waiting to see those details.

So have they conducted an audit? #

Since they haven’t released details publicly, if they conducted an external audit, that would bring some trust. So, recently I asked, and this is what they had to say:

@adamcaudill Thanks for your important question. There hasn’t been an audit yet due to work in progress, but will be done this year.
— Ensafer (@Ensafer) March 21, 2014

After the delay in getting useful details published, I’m not hopeful that we’ll see the results of an audit in the near future.

TLS & Safe Downloads #

I really wish that the lack of details was the only concern – but it’s not. The first thing I noticed is that their web site doesn’t force TLS, so I manually switched to HTTPS, unfortunately the result wasn’t what I was hoping for:

Well, that’s not encouraging. Let’s take a look at the download link:

http://get.ensafer.com/mac/prod/Ensafer-1.0.8.dmg

When you try the same link over HTTPS, it’s even worse:

For a security product, I’d expect the download to be over HTTPS to prevent an attacker from redirecting a victim to a malicious version. This isn’t the kind of mistake I’d expect from people building advanced security tools. When you see issues like this, it’s common to see more problems, so this may just be the tip of the iceberg.

Is it trustworthy? #

I would like to say that it’s safe to use, and that it lives up to the promises made – but they haven’t made enough information available for people to make an informed decision. If you add the lack of information with such basic mistakes as not making the download available over HTTPS, it doesn’t instill much confidence. Companies focused on security should know better.

When you make decisions about what tools you use, you have to look at the full picture – and Ensafer is a great example of that. They’ve focused first on a pretty website, adding features – but not assuring trust. At this point, the only evidence of their security is the use of buzzwords.

Adam Caudill

Testing for SWEET32 with YAWAST

Testing for SWEET32 isn’t simple – when the vulnerability was announced, some argued that the best solution was to assume that if a TLS server supported any of the 3DES cipher suites, consider it vulnerable. The problem is, it’s not that simple. On my employer’s corporate blog, I wrote about practical advice for dealing with SWEET32 – and pointed out that there are ways around the vulnerability, and some are quite simple.

Crypto Front Door: Everyone Welcome!

For decades, the US Government has fought — sometimes with itself — to prevent the use of secure cryptography. During the first crypto war, they allowed strong cryptography within the US, but other countries were limited to small keys — making brute force attacks practical. But what about those pesky US citizens? They didn’t really want them to have strong crypto either — enter key escrow. What is key escrow? According to Wikipedia:

On Opportunistic Encryption

Opportunistic encryption has become quite a hot topic recently, and blew up in a big way thanks to an Internet Draft that was published on February 14th for what amounts to sanctioned man-in-the-middle. Privacy advocates were quickly up in arms – but it’s not that simple (see here). As pointed out by Brad Hill, this isn’t about HTTPS traffic, but HTTP traffic using unauthenticated TLS; thanks to poor wording in the document, it’s easy to miss that fact if you just skim it.

Battle Fronts in the Crypto War

or, These aren’t the droids apps you are looking for… The Chinese government has passed new anti-terror legislation, drafts of which have been criticized for months due to broad language, and the massive privacy concerns. This legislation is a critical move in the global Crypto War – effectively giving the Chinese what the FBI has been seeking for well over a decade: a CALEA-style law, that mandates providers be able to supply law enforcement with decrypted data.

On Apple, Privacy, and Device Control

If you’ve bothered to look at Twitter or any technology news source, you’ve seen that Apple made a major announcement: Expanded Protections for Children. This has been written about by countless outlets, so I’ll assume you’re familiar with the basics. The announcement covered a few new features being added to the next version of Apple’s operating systems, namely: Scanning of inbound and outbound messages for sexually explicit images. Scanning images being uploaded to iCloud for CSAM.