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I recently wanted to use Emoji in a paper, but I did not want to force my contributors into using LuaLaTeX or XeLaTeX (in which you can just use fancy fonts). So as a work around, I set up a small helper document that helps me set up emoji as (vector) images instead, which I can then include using \includegraphics{} . To set this up, I create a folder called emoji and create the a file called…
Recently, I have computed the sizes and measured the performance of post-quantum TLS (both PQ key exchange and post-quantum authentication). In these experiments, I have examined combinations of Kyber, Dilithium, Falcon, SPHINCS + -(sf), HQC and (custom versions of) XMSS MT . The experiments include measuring their performance over two network settings, one high-bandwidth, low-latency and one…
After I found myself in a vacation rental with and , we thought it would be fun to have a go at a few of ’s 2022 2023 ctf challenges as team #RU (long story relating to Radboud University). Then I thought it would be fun to post a writeup of the challenges that we solved. yor The Yor challenge code was given as follows: #!/usr/bin/env python3 import random greets = [ "Herzlich willkommen!…
After a I decided I should write down a few of the tips and tricks I’ve learnt over the years of writing papers and many other things in LaTeX. Pandoc If you’re very sure you need a full-blown LaTeX document, continue reading below. Otherwise, triple and quadruple-check if you can’t just get away with writing Markdown and just use pandoc to convert your document to LaTeX/PDF.…
If you’re curious about some of the things I’ve worked on while at Cloudflare, see .
Find this post on the Cloudflare blog:
This post can be found on Cloudflare’s blog.
I’ve been playing with various task managers / personal life management tools. These are some of my notes and thoughts. Todoist review Pro: Filters (custom perspectives) Smart task editor when adding tasks Great web interface and decent mobile apps Super flexible recurrence (“every third…”) Cons: No review: discovering stale tasks is fairly low No way of marking tasks as “ready” or…
Douglas and I appeared on Nadim Kobeissi’s new podcast Cryptography FM to talk about . You can find the episode .
This article previously appeared in ’s Thabloid, in the . It was written at the end of May and may not reflect current practice at Radboud University. Note This article is getting a lot of traffic from people who appear to be looking for a way to defeat Proctorio. This article is discussion of some of the technical and ethical issues about online proctoring. It will not tell you how to cheat…
I like to use , because it gives me consistent results and it contains almost everything relevant to me. However, as crypto.bib is over 725000 lines long, parsing it to create the bibliography takes a long time. This means that my $\LaTeX$ compile jobs take much too long. I have now written a python script that will allow you to extract entries from large bibliographies. This script will take your…
In the RFC for TLS 1.3 ( ) especially, the key exchange is defined in terms of (EC)DH key shares being exchanged. This limits us to algorithms which support non-interactive key exchanges, while this is not necessary for the security of TLS 1.3 as defined by RFC8446. 1 As we would like to implement (post-quantum) KEMs into TLS 1.3, we will now describe the changes to the spec that would be…
The new TLS 1.3 standard \[1\] does not yet provide any support for post-quantum algorithms. In this blog post we’ll be talking about how we could negotiate a post-quantum key exchange using a (post-quantum) Key Encapsulation Mechanism (KEM). In the NIST Standardisation effort \[2\] , many KEMs are currently under consideration. What is a KEM A KEM is a set of functions that can be used to…
I’m going to Cuba as my submission to Latincrypt 2017 was accepted! The paper is called Energy-efficient ARM64 Cluster with Cryptanalytic Applications: 80 cores that do not cost you an ARM and a leg . Visit the . I’ll upload the paper once I’m done editing.
You can set up SSH to prefer Elliptic Curve cryptography over RSA, and use modern key exchange algorithms without exposing yourself to -style attacks. It’s also good to get rid of SHA1 and MD5. A good resource is . You can basically copy the config. Caveat: I found out that the version of Paramiko in Debian Jessie does not support SHA2 hashes or ECC in the key exchange. Paramiko was used in…
In July, Peter Schwabe, who supervised my Bachelor’s thesis project, suggested to submit my work to the . It then turned out that the deadline was the next day, so I had to work hard to convert 28 pages of thesis into a paper of 4 pages. To my own suprise my paper was accepted for a poster presentation. It was very interesting and challenging to tell the people at the conference (which was…
today had an where they announced they were going to give away €100 in Bitcoin. They were going to put up a Bitcoin wallet private key as a QR-code on the screen. It seemed to me like a fun project to try and grab that Bitcoin. I coded an app that takes a screenshot every couple seconds and then tries to detect all QR-codes in it. If any of the codes look like a private key, I then used the API to…
I’ve had to rename some fields today with MongoEngine. Using the following approach, I was able to raise DeprecationWarning s when old version were used. Create the following function. It returns a property that will access the new variable name. def deprecated_field ( new_name ): """Wrapper for deprecated fields""" def getter ( self ): warnings . warn ( 'This field is deprecated, use {} ' .…
Prøst is an authenticated encryption cipher and a contestant in the CAESAR competition for Authenticated Encryption. For my bachelor thesis research project, I’ve implemented Prøst on ARM11. You can find more information about this project on .
Today I’ve tried to globally install . That was a bit of a pain because it has no global config files. Quick and dirty how-to: Add XDG_CONFIG_DIRS=/etc/xdg to /etc/environment if it isn’t already set, Copy the config to /etc/xdg/powerline , Customize config, Load powerline from /etc/bash.bashrc , ~/.zshrc , etc. My config can be found at
Today, I enabled perfect forward secrecy on my nginx installation. I’m writing down the config so I can easily find it later. I just put the below config lines in a file called /etc/nginx/conf.d/ssl.conf and now show PFS is enabled. ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_prefer_server_ciphers on; ssl_ciphers…
I recently read The Circle by Dave Eggers. It is a bit like the classic dystopian novel 1984 being brought up to date in the age of smartphones, apps and Google, Facebook and Twitter. Though it does not have very novel ideas, Eggers paints a picture of the tyranny of the masses and of the consequences of a society that only has a surface level. Though the characters are pretty flat and lead…
I have a fairly creative ssl setup on my webserver: I run my own ‘certificate authority’ which signs the server certificate; I have a bunch of alternative names specified; The CA certificate sits on an ePass 2003 PKI token. I’m writing down how I sign certificates in this context so I can use this to look up the procedure instead of spending hours in DuckDuckGo. This is more of a…
is een kort geleden gelanceerde website waarop je digitaal door kranten en tijdschriften kan bladeren. Denk je “goh, dit wil ik wel lezen”, dan kun je met één klik het artikel openen en tegen betaling van zo’n € 0,10 het artikel lezen. Dit alles in een simpele, maar heel effectieve website. Ik moet zeggen, ik ben om. Dit werkt heel goed. Ik zie het al gebeuren dat over een paar…
As you can see, this site has been overhauled! I am now using the pretty awesome static site generator. The source of my website is on .
For crypto code it's important that it's time-invariant, otherwise it is vulnerable to timing attacks. I've had to build this time-invariant equality test from scratch, because I couldn't find something on Google. I hope it's useful to someone else. ; ; Linear time equality ; ; Author : thom ; ; based on this C code : ; int equals ( int a , int b ) { ; unsigned long long t = a ^ b ; ; return 1 -…
It's been a while since I posted. Today I decided it was time to behave myself a bit like the pretentious hipster I secretly am and post a bit about the music that I discovered lately. London Grammar - If You Wait (2013) <p>London Grammar are an UK based indie pop band. They released their debut album <em>If You Wait</em> a couple of weeks ago. <a title="Pitchfork Review"…
While playing with my ePass2003 on my Gentoo installation today, I had some trouble getting it to work. As it turned out, you need the following use flags enabled: # /etc/portage/package.use dev-libs/opensc pcsc-lite secure-messaging Hope this helps someone.