January 26, 2016

The Wrong Number Attack

XMPP is federated, similar to email, which means different domains can connect to each other. Back in the early days, when a server initiated a connection to a server, the initiating server could be reasonably sure it connected to the right place as it resolved the DNS records (remember, it’s 1999). But the receiving server has no guarantee on whether the incoming connection was actually from the domain it claimed.

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December 28, 2015

Common DH groups

To deal with the logjam attack, I was looking for a set of all “common” Diffie-Hellman parameters to update xmpp.net, yet I wasn’t able to find those easily. Even just searching for the hexadecimal representation of commonly encounted primes often didn’t lead to the document they were specified. Here I’m documenting those that I found and where they are from.

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December 18, 2015

Out with octopress, in with Hakyll

As you can see, the layout of this blog has changed. I was updating this blog so little, every time I did Ruby had broken everything (or so it felt like). I don’t like the idea of having to learn Ruby or gem to blog, so I’ve decided to switch to something else.

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April 17, 2015

Validate the encoding before passing strings to libcurl or glibc

Lets start with a simple example in php:

setlocale(LC_ALL, "nl_NL.UTF-8");

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, $_GET["url"]);


This code is broken, can you tell how?

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January 23, 2015

Multi-end to multi-end encryption

It’s a week until the XMPP Summit in Brussels, which I won’t be able to attend. How­ever, I do have some thoughts about two of the subjects that are on the agenda that I wanted to share.

Carbons/MAM and e2e-encryption seem to be moving in two completely opposite directions: MAM wants to store messages server-side, while e2e protocols like OTR want to ensure those stored messages are useless. But I don’t think they’d have to be mutually exclusive. I think it would be possible to find a solution that unifies the two concepts.

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