The Fenrir Project

Transport, encryption, authentication protocol

This project is maintained by Luca Fulchir

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Fenrir's Blog

Welcome to the blog tracking the Fenrir project

This blog will be used to track and -why not- discuss all the choices, design features and advancements of the project, so you might find both technical posts and random thoughts.

Currently working on:

From Section Description
2021-01+ D4 New Object storage
2020-12 Studying Rust & nix New base for server and future projects
2018-10 - 2020-11 Nothing :( too much work, no time for opensource

Rust, D4 and Nix

d4 object storage rust nix abstraction

Lazying and recuperating time over, work on D4 has started.

But for now, just an update on Rust and D4, with a touch on nix.

This post will mostly be about abstractions and where the world seems to be going.

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New Beginning


No, I’m not dead. It’s been 2 years since the last update, sorry.

The reason no updates have happened in 2 years, was my last job. Too much burnout, too little time for my life, so I quit.

Out with the job, in with the Open source.
Here is what is going to happen now

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Tyr tunnel error correction

Following the earlier post I will now explain a bit this new small project of mine, Tyr, which should be completed fairly soon (at least in its first version)

Tyr is basically a transparent, opportunistic error-correcting tunnel.

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Update: RaptorQ

RaptorQ error correction

Since this blog is less used than I would like to, I have decided to start writing about the other projects I am working on, all somehow connected to the Fenrir Project.

So I will start writing about libRaptorQ and Tyr (not public yet).
Both these projects are related to error correction, and while libRaptorQ will be used in Fenrir, but I will talk about Tyr in a second post.

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Refuting the need for cleartext

QUIC middleboxes encryption

Today QUIC made it to the HackerNews headline, and in the comments I found links to “The hidden cost of QUIC and TOU

The short version is that protocols that encrypt everything make debugging more difficult, and middleboxes can’t do their job anymore.

Let’s look into the details of these claims

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Reserved Handshakes

Handshakes Fenrir stateless

While re-implementing the full-security handshake in the rewrite of libFenrir, I came across the old problem of stateful vs stateless handshakes, and what it means for (D)DOS attacks.

After thinking about it for a while, let me introduce you to a slight modification of the full-security handshake to have the best world of bot stateful and stateless handshakes.

We will go through various design, and quickly analyze various solutions from TCP to minimaLT.

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Who watches the watcher?

Fenrir proverif proof

Formal proofs are nice. Programs like proverif are even nicer, because they do the work for you.

It means that we have a way to check for the correctness of our model, independently from our implementation.

…But what happens when there is a mistake in the formal proof?
And how do we fix it?

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Status Update

Update Fenrir

What is happening? Has the project stalled?
Not really, I’m just working behind the scenes.

Since you might also like some kind of report, I added a section “currently working on” on the blog page.

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Paper rejected

Update Fenrir paper ITA-SEC

I submitted a paper highlighting Fenrir to a security conference ITA-SEC.
The paper was rejected. Let’s see why and what it meas for the Fenrir project.

TLDR: no big deal, keep working.

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Status Update

Update libRaptorQ

A lot of time passed, what happened?

I have not been slacking, but I have not been working much on Fenrir lately.
That’s because a lot of work has been done in libRaptorQ, that Fenrir will use.

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