posts/my-first-rust-crate.md


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37

---
title: "My first Rust crate"
description: "A command-line application and Rust library to compute the WPA-PSK of a Wi-Fi SSID and passphrase."
published: 2022-01-03
---

Recently I decided to give Rust another try -- if only to compare it to Haskell.
After reading through the decent documentation, especially [*the book*](https://doc.rust-lang.org/book/), I felt prepared to write some remotely useful application: a command-line application to compute the WPA pre-shared key of a Wi-Fi from its SSID and passphrase.

Why?
Because I needed to manually connect to some wireless networks with *special* and sometimes downright *invalid* SSIDs and passphrases.
Of course, the popular [wpa_supplicant](https://hostap.epitest.fi/wpa_supplicant/) comes with a similar tool, `wpa_passphrase(8)`.
But where's the fun in that?

So here it is: my very first Rust crate, `wpa-psk`, on [crates.io](https://crates.io/crates/wpa-psk/0.1.0) and [docs.rs](https://docs.rs/wpa-psk/0.1.0/wpa_psk/).

The command-line interface looks like this:

    $ wpa-psk "123abcABC.,-" "456defDEF *<:D"
    0x8a366e5bc51cd5d8fbbeffacc5f1af23fac30e3ac93cdcc368fafbbf63a1085c
    
    $ wpa-psk --force "bar" "2short"
    0xcb5de4e4d23b2ab0bf5b9ba0fe8132c1e2af3bb52298ec801af8ad520cea3437

And the Rust interface looks like this:

    let ssid = Ssid::try_from("home")?;
    let passphrase = Passphrase::try_from("0123-4567-89")?;
    let psk = wpa_psk(&ssid, &passphrase);
    assert_eq!(
        bytes_to_hex(&psk),
        "150c047b6fad724512a17fa431687048ee503d14c1ea87681d4f241beb04f5ee"
    );

Note the validating newtypes `Ssid` and `Passphrase`.
I like that.
Feels like Haskell :)