This blog is illegal!

At Zeall, we offer our employees the courtesy of free hosting for their personal blogs, in hopes of furthering their professional image. Today, we completed the migration of the employee Wordpress instance from a shared hosting provider to its own VPS, and simultaneously deployed TLS certificates (thanks, Let’s Encrypt!) for all domains hosted there (including this one).

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Blue Coat’s position as a Certificate Authority, and what it means for you.

Recently, Blue Coat Systems has been approved as an intermediate certificate authority. If you aren’t versed in network security, this means nothing to you. However, be assured that it is a big deal.

Blue Coat is primarily known as  a vendor of application-layer (deep packet inspection) firewalls. In other words, they help people sniff your data — primarily in order to censor the Internet. Maybe your company’s firewall blocks access to YouTube and Facebook while you’re at work. That’s no big deal — Blue Coat delivers something a bit more sinister.

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What’s inside a PEM file?

As you probably know, PEM is a base64-encoded format with human-readable headers, so you can kind of figure out what you’re looking at if you open it in a text editor.

For example, let’s look at an RSA public key:

-----END PUBLIC KEY-----

We can see that we have a public key just from the header. But what’s all the base64 stuff? If it’s a public key, we know that there should be a modulus and an exponent hidden in there. And there’s also probably some kind of hint that this is an RSA key, as opposed to some other type of key.

That base-64 payload actually has the potential to contain a lot of information. It’s an ASN.1 (Abstract Syntax Notation One) data structure, encoded in a format called DER (Distinguished Encoding Rules), and then finally base64-encoded before the header and footer are attached.

ASN.1 is used for a lot of stuff besides keys and certificates; it is a generic file format that can be used to serialize any kind of hierarchical data. DER is just one of many encoding formats for an ASN.1 structure — e.g. there is an older format called BER (Basic Encoding Rules) and an XML-based format called XER (you can probably guess what that stands for).

But anyway, what is inside that public key? How can we find out?

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My first adventure with Let’s Encrypt on nginx, dovecot, and postfix

Let’s Encrypt is old news by now. It launched back in December, so it has been giving away free DV certificates for nearly four months now. Being a TA for a Computer Security course, it’s about time that I actually tried it out.


Let’s Encrypt is a free certificate authority. They grant TLS certificates that you can use to secure your webserver. They are Domain Validated (DV) certificates, which means they will verify that you control the domain name you are trying to certify.

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Demonstrating the double-DES meet-in-the-middle attack


DES (Data Encryption Standard) is an old-school block cipher which has been around since the 1970s. It only uses a 56-bit key, which is undeniably too short for use in the modern day. Between the realization that DES is weak in the late 90s and the invention of AES in the early 2000’s, Triple-DES had a brief time to shine.

Triple-DES is just what it sounds like: you run the DES algorithm three times. You use two 56-bit keys, K1 and K2, and apply them in the order K1K2K1. The result is a cipher with 112 bits of key strength.

Students often ask me, why not just encrypt twice: K1, K2, done? The reason is that this construction is vulnerable to a particular chosen-plaintext attack, which we call the meet-in-the-middle attack. That is, if the attacker knows your plaintext in addition to your ciphertext, he doesn’t have to try all 2^112 keys. The maximum amount of work he has to perform is actually only 2^56 — not much more than to break single DES.

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Digital privacy: Where do you draw the line?

I recently had a friendly debate on IRC about how much privacy you really need for it to be considered “enough.” Arguably, the answer is “there is never enough.” And still, there are plenty of people who would be perfectly content having no privacy at all.

Many argue that the key to privacy is actually transparency. If we use open source software, we can all audit it to be sure it is free of backdoors and bugs which may leak information. Perhaps this is why increasingly many users (but unfortunately still less than 2% overall) now prefer Linux to proprietary operating systems. But even among Linux users, there is not much knowledge about how deep the privacy rabbit hole goes.

Before I return to the debate about how much privacy is really sufficient, I’d like to give a quick overview of some of the tools one can use to preserve their privacy. I will discuss four levels of privacy: network, OS, firmware, and hardware.

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What goes around comes around: Is the Juniper backdoor the feds’ fault?

By now, everyone should know that Dual EC DRBG is unsafe. Way back in 2013, it was revealed that it has many weaknesses, some of which were traced back to the NSA (with the help of Edward Snowden’s leaks). Whether or not it really was inserted by the NSA, the backdoor has been proven to exist and is easily exploitable.

For those of you who don’t know, a DRBG, or “deterministic random bit generator,” is essentially just a way for computers to generate random numbers. We need random numbers for cryptography — they form the basis of our secret keys. If a random number generator is compromised, then the keys it produces are unsafe to use.

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No, fingerprints are not secure

Authentication is the process by which a system determines whether a particular user is allowed to access it. There are three widely agreed-upon methods to authenticate a user:

  • Something you have.
  • Something you know.
  • Something you are.

When you use your key to unlock your front door, you are authenticating yourself using something you have. In information security, passwords are the most popular method of authentication; they are something you know. Authentication by something you are (i.e., biometrics) has historically been only a niche practice, but in recent years it has caught on in the realm of consumer electronics.

When Apple announced Touch ID in late 2013, security experts immediately voiced their concern. The authentication mechanism was quickly compromised, and there is still very little that Apple can do about it. Why, you ask? Because fingerprints are inherently insecure.

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Dell joins Lenovo’s MITM bandwagon

Several months ago, news broke that Lenovo was shipping a rogue root certificate with its laptops. It was included as part of a pervasive adware called Superfish, which had already been annoying users (and support techs) for years prior to it being included by default on these machines. More recent news indicates that this is only the least of security concerns for Lenovo users — it appears that there are also backdoors in the hardware itself, and now governments around the world have blacklisted Lenovo as a vendor for this reason.

Dell and Lenovo have been battling over PC market share for years now, and this understandably gave Dell a pretty decent boost in popularity. This makes Dell’s latest action all the more surprising.

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Is there a war on privacy?

Governments do not trust encrypted data.

Some high-profile names have suggested in the past few months that we encrypt absolutely everything we transmit over the Internet. The reasoning behind this proposal is that if everything is encrypted, then governments cannot apply as much scrutiny to individual messages. If we only encrypt data that we want to hide, then that data will interest them. If the data interests them, the government will easily find a way to obtain (and decrypt) it.

Last week, allegations were made that the US government paid Carnegie Mellon security researchers a large sum of money to defeat Tor’s privacy mechanisms. The federal government certainly has a history over overstepping its boundaries with surveillance, but this is an unprecedented and frightening leap toward a world without privacy.

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