I'm sorry, but this simply isn't true. Software of far, far greater complexity than WhatsApp has been reverse engineered comprehensively by hobbyists and amateurs. Meanwhile, professionals have pretty sophisticated tools for doing this work at scale.

This seems to be the same angle played every time the analysis of crypto tools comes up on HN.

(Almost always) when someone mentions the 'impossibility of analysis' of closed-source programs they are actually referring to the difficulty in doing so -- not actually stating that it's impossible.

It is easier to look through source code.

Now, if we're progressing through this conversation according to script, it will be mentioned that open source projects have had tremendous security problems, too. (OpenSSL comes to mind..)

But that's beside the point expressed.

The only point, and it's the point that was originally expressed, is that open source code is easier to look through than a closed code base.

The hurdles posed by closed source, although not impossible to jump, significantly hinder the progress of analysis.

Is this not true?

Not necessarily. People who spend their days writing source code tend to think in terms of source code because that's what they know. People who spend their days analyzing binaries don't. Be mindful of the difference between difficult and unfamiliar.

I'm sorry, but if you look upthread, the comment I responded to not only didn't say that verifying open source was easier, but actually made the extreme claim that there was in principle no way to verify closed source software at all.

Meanwhile, addressing your (different) argument directly: sure, reading C code is easier than reading assembly code, and reading Python is easier than reading C. The easier it is to read a program the easier it is to reason about it.

But:

* It's not terribly difficult to reason about the functionality of messaging software in any language.

* WhatsApp is an extremely high-profile target; it would be weird if people hadn't reversed it by now, since less well-known programs that are much harder to reverse have been productively (as in: findings uncovered) reversed.

* The particular things we're looking for in a program like WhatsApp fall into two classes: (1) basic functional stuff like data flow that is even more straightforward to discern from control flow graphs than the kinds of things we routinely use reversing to find (like memory corruption flaws), and (2) cryptographic vulnerabilities that are difficult to spot even in source code, because they're implemented in the mathematical domain of the crypto primitives regardless of the language used to express them to computers.

Sure, though. It is easier to spot backdoors in open source software. It's just not capital-H Hard to do it in closed-source software, so this open vs. closed debate about backdoors is usually a red herring.

> less well-known programs that are much harder to reverse have been productively > It's just not capital-H Hard to do it in closed-source software, so this open vs. closed debate about backdoors is usually a red herring.

No, you are oversimplifying the problem a lot.

In an Open Source project it is possible to create transparency in the development process by every commit public and allowing 3rd parties to mirror the sources repositories as well as perform reproducible builds, sign the artifacts and so on.

Once a project has been reviewed, it becomes pretty difficult to sneak in a backdoor later or deliver a backdoored build only to some specific targets.

In case of closed source smartphone applications it's very Hard to reverse engineer every single release simply because it takes a staggering amount of work.

It's also Hard to verify that some unsuspecting users are receiving a "custom" apk and block the update automatically.

Nope. Professional security people have been using binary diffing tools to solve this problem since the early 2000s.

>> it's very Hard to reverse engineer every single release > Nope

Nope to what? Are you saying that binary diffing is possible or that the amount of effort required is (remotely) comparable with analyzing source code?

I would like to see evidence supporting the latter statement, if this is what you are saying.

You keep saying this. Can you back your claims? In particular, the claim that Whatsapp has been extensively reverse-engineered?

Your argument is the same one as "nuclear submarines are impossible to build because I just thought about it for five minutes and can't build one". But Electric Boat Corporation from Groton, Connecticut delivers them regularly, on time and under budget (!). Googling around will tell you that these things exist and people do build them.

No, that's not at all my argument. I didn't ask me to show me a completed nuclear submarine. I asked you to show me a Whatsapp reverse engineer.

You can use Google to prove to yourself that either the infosec industry really exists (including skilled full time reverse engineers) or there is a vast conspiracy. Same as you would prove to yourself that nuclear submarines exist, without ever being allowed onboard one to inspect it.

Consider all the people who study closed source browsers (MSIE) and plugins (Flash) to write malware. Consider all the people who reverse engineer malware to write protections or ransomware decryptors.

The people who can do such work don't work exclusively for the NSA and Google, and you can probably hire them for $1000 a day. but none of them will do tricks for you for free just to prove that they exist. They're too busy making money.

I saw some of the work described in this [1] excellent paper on reverse engineering NSA's crypto backdoor in Juniper equipment being done live on twitter. People exchanging small pieces of code, piecing together all the changes that were made in order to allow passively decrypting VPN traffic.

1 - https://eprint.iacr.org/2016/376.pdf

Are you asking me to "back up" the claim that security researchers use BinDiff tools to reverse out vulnerabilities from vendor patches?

At one of the better-attended Black Hat USA talks last year, a team from Azimuth got up and stage and walked the audience through an IDA reverse of the iOS Secure Enclave firmware. Your argument is that it's somehow harder to reverse a simple iOS application?

You keep saying it's easy, I keep saying, then do it and show me.

Have you ever heard of the obfuscated C contest? Even with the code in front of your face and looking innocent it's hard to see what it does.

When you only have decompiled assembly, obfuscation is much easier.

At the binary level, obfuscation is powerful but obvious. Is iOS WhatsApp meaningfully obfuscated?

Considering iOS forbids self modifying code, lots of tricks aren't even available.