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Building a travel toolkit

2025-01-02T00:00:00Z

The container for my toolkit, a UGREEN “travel accessories” bag

For a while now, whenever I’ve traveled anywhere I’ve dumped a selection of tools into my backpack just in case I need them. Originally this was mostly focused around being able to open and fix my laptop if anything went wrong, but over time has slowly expanded to include other useful tools.

Repeatedly packing these tools and then returning them to where they belonged was tedious, though. I couldn’t just leave them in the backpack as I often needed them for non-travelling purposes, and I didn’t want to just buy duplicate tools that spent most of their life a few meters away from each other, so I ignored the problem and just dealt with the tedium.

Eventually I acquired enough tools that — while not quite duplicates — I wouldn’t miss often if they were kept in the backpack. Building on these I’ve created a little travel toolkit that contains everything I might want (and more) while away.

The base

The biggest challenge I had before was finding a screwdriver set. I have an iFixit Mako set that did the in-and-out-of-the-bag routine for several years. Nothing else covered the range of drivers I wanted for generic electronic tinkering and more chunky work. I finally found one in the form of a Wera Tool-Check PLUS TR-Edition. “TR” stands for “Tool Rebel” and is Wera’s “fan club” brand. Its signature features over the normal Tool-Check PLUS are a fancy fabric case and a 152mm bit extender; but it also comes with a much different set of bits, which is why I picked it up.

Here’s a comparison

Type	Standard version	Tool Rebel edition
Phillips	2x PH1 3x PH2 1x PH3	1x PH00 1x PH0 1x PH1 1x PH2 1x PH3
Pozidrive	None	1x PZ1 3x PZ2
Slotted	1x 5.5mm	1x 4mm 1x 4.5mm 2x 5.5mm 1x 6.5mm
Torx	1x T10 1x T15 1x T20 1x T25 1x T30 1x T40	1x T10 1x T15 1x T20 1x T25 1x T30 1x T40
Security Torx	1x T10 1x T15 1x T20 1x T25 1x T30	1x T25
Hex	1x H3 1x H4 1x H5 1x H6 1x H8	1x H1.5 1x H2 1x H2.5 1x H3 1x H4 1x H6 1x H8

There are only five bits present in the standard version that are missing in the TR edition: 5mm hex (pretty uncommon) and four sizes of security torx (rare). In exchange for those and the removal of a bunch of duplicates, you get two extra phillips sizes (0 and 00, both very useful for electronics and spectacles), some pozidrive bits (extremely common on random hardware/furniture/etc), smaller hex bits (for electronics, 3D printers, and so on), and a few other bits and pieces.

Overall it’s a vastly superior selection for my needs. And while it doesn’t have the full range of bits provided by the iFixit kit, it does cover almost everything I’m ever actually likely to need while travelling, and it’s probably around a third of the size.

The other core part of the toolkit is the bag. I had a UGREEN “travel accessory” bag hanging around unused, and noticed it was almost the exact right size for the Tool-Check. Now, how many other tools could I stuff in there?

All the tools

The array of tools that make up the travel toolkit

The kit can be broken down into a few sections:

Screwdriving

The aforementioned Wera Tool-Check
Its 152mm bit extender

I’ve talked enough about this already, I think, so I’ll spare you any additional commentary on screwdrivers and bits.

Splitting, gripping and cutting

Engineer tweezers
Engineer mini snips
Engineer mini screw removal pliers
Knipex mini waterpump pliers
Two iFixit spudgers (one metal, one plastic)
iFixit jimmy

I have bigger or slightly different versions of these that stay in my normal toolkit. The tweezers and snips are useful in a variety of situations, and the spudgers are handy for getting inside laptops and other devices. The pliers are less useful, but they’re one of those things where when you do need them there aren’t any good alternatives.

Sewing

Two needles
Some black thread
Set of mini clips

You never know when you’re going to rip a seam in something. I find the clips a lot less fiddly than using pins for keeping material in place when I’m trying to sew.

Computering

Retractable ethernet cable
RJ45 coupler
USB-C to RJ45 adapter
Dual USB-A and USB-C thumb drive, with an Arch ISO on it

Sometimes Wi-Fi just doesn’t cut it, or you need to fiddle with a router that doesn’t expose its admin UI over Wi-Fi. The USB-C adapter is for use with my phone, as it’s often easier to move that get the laptop where it needs to be.

I can boot from the thumb drive into an Arch environment, and from there reinstall my laptop from scratch if needed. There’s enough space left over so it can be used to transfer files as well.

Miscellaneousing

Fabric tape measure
Spirit level
Sharpie
Superglue
Spare batteries: 2 CR2032s, 2 AA, 2 AAA

I’m almost certain I won’t use the spirit level, but it’s tiny and I had a spare so it went in. Everything else is just in the “generally handy to have” category.

Putting it all together

The nicely-organised side of the toolkit

The Tool-Check PLUS fits almost perfectly into one side of the UGREEN bag, leaving a little wiggle room along the side for the longer parts like spudgers. The middle pockets can’t fit much in, but keep the batteries and sewing bits out of the way. Everything else is in a big zip-up compartment in the other side, which is slightly messy but still easy enough to dig through to find whatever I need.

The complete kit weighs in at around 1.2KG, so it’s not exactly lightweight, but it goes in a bag with a heavy laptop and all of its peripherals so it’s not as noticeable as it might otherwise be.

It remains to be seen how much use I’ll actually get out of any of this. Maybe I’ll put a bit of paper in so that I can track how often I use each tool…

Creating an offline GnuPG master key with Yubikey-stored subkeys

2016-08-11T00:00:00Z

A pair of Yubikeys

I recently noticed that I’d accidentally lost my previous GPG private key — whoops. It was on a drive that I’d since formatted and used for a fair amount of time, so there’s no hope of getting it back (but, on the plus side, there’s also no risk of anyone else getting their hands on it). I could have created a new one in a few seconds and been done with it, but I decided to treat it as an exercise in doing things properly.

Background: GPG? Yubikey?

GPG or GnuPG is short for Gnu Privacy Guard, which is a suite of applications that provide cryptographic privacy and authentication functionality. At a basic level, it works in a similar way to HTTPS certificates: each user has a public key which is shared widely, and a private key that is unique to them. You can use someone else’s public key to encrypt messages so only they can see them, and use your own private key to sign content so that others can verify it came from you.

A Yubikey is a small hardware device that offers two-factor authentication. Most Yubikey models also act as smartcards and allow you to store OpenPGP credentials on them.

Introducing subkeys

GnuPG supports subkeys, which provide fairly significant security advantages. Instead of just having a single public and private key, you have a master pair and then any number of subkey pairs. The subkeys are automatically associated with the master key, but they can be revoked independently.

Having a master key fall into the wrong hands is a problem — you have to revoke the whole thing (assuming you have access to a revocation certificate) and start again, convincing everyone else that your new key is the “real” you. With subkeys, you can issue a revocation signed with your master key and then sign some new subkeys. There’s no loss of trust, and as long as people refresh your key from a keyserver, everything carries on as normal.

The other advantage to using subkeys is that you can keep the master key elsewhere. It doesn’t need to be routinely accessible, and using it doesn’t require access to the Internet. The master key is kept offline, significantly reducing the risk of anything bad happening to it.

Setting up a secure environment

My main desktop runs Windows, and most of my other devices are work ones which come with automatic backups and network mounts that I don’t fully grok. Neither of those is a particularly good option if I want to do something security sensitive.

Tails is the defacto choice for a secure, live linux system, so I went through their installation process and eventually ended up with a USB drive that can boot into Tails. The installation process from Windows is slightly convoluted, as it involves creating a bootable Tails image, then booting to that and using the Tails installer to create the real image on a different drive. If you’re starting on a Linux box, you can just use the Tails installer directly instead of doing the two-drive shuffle.

Just to be completely paranoid, I disconnected my PC from the network before booting Tails. This is known as air-gapping, and is done to eliminate the possibility of a remote attacker doing something to your system. Ideally the machine never would have been connected to the network, but I didn’t happen to have an unused machine laying around.

The final thing I needed was a secure place to store my master key. I opted for an IronKey — a hardware-encrypted USB drive that self-destructs if there are too many unsuccessful attempts to access it. It works out-of-the-box on both Windows and Linux, presenting a small unencrypted drive with software to run to interact with the secure partition.

Creating the keys

Now I had a nice over-the-top setup it was time to actually the keys. There is an excellent guide by Simon Josefsson that walks through the entire process of creating the master key, creating three subkeys, and then transferring them to a Yubikey.

The only point where I had to deviate from Simon’s guide was setting the machine up to work with the Yubikeys. I was setting up two keys (a nano and a neo), and one just worked out of the box with the version of libykpers-1-1 that was in Tails’ apt repository. The other needed a slightly newer version but that was also available in apt and can be selected by specifying the version manually as pointed out in this GitHub issue. The version numbers have since changed, but apt-policy makes it easy to figure out what’s needed. As I was using an air-gapped system this process was a bit more complicated than it sounds, involving several USB drive transfers.

After finishing the guide, I had my master key and a pre-generated revocation certificate stored securely on my IronKey, and the three subkeys stored on each Yubikey. Time to go back to Windows.

GPG, Windows and SSH

Now with the IronKey disconnected and the master key out of harms way, it’s time to go back to Windows. I downloaded the GnuPG Modern distribution and followed the instructions at the end of Simon’s guide to import my public key and make GPG aware of the subkeys on the Yubikey. After that Enigmail was able to sign and encrypt e-mail in Thunderbird.

XKCD #979: Wisdom of the ancients

Next up, I enabled PuTTy support and started the GPG agent, as documented over on Yubico’s site. This allows you to use the authentication GPG key to authenticate SSH sessions from PuTTy. To find the SSH key you need to add to .authorized_keys, simply run gpg --export-ssh-key. At first I could SSH into a host but not use agent forwarding. After lots of unsuccessful Googling, I realised that GPG couldn’t access the key anymore locally. Another quick search and I found a forum thread where someone had the same issue and found it was a problem with exclusive access to the card. They even passed on their wisdom and updated the thread with a solution, which got everything working for me.

VMWare

I have a Ubuntu image running inside VMWare on my desktop that I use for most development activities. I’m unlikely to want to sign e-mail, but I probably want to sign commits (especially now that GitHub exposes verified signatures).

To do that I need to pass the Yubikey through to the virtual machine. In its default configuration, VMWare recognises the Yubikey device but doesn’t pass it through correctly. You need to configure it to allow HIDs, after which gpg --card-status starts working from the VM.

Unfortunately passing through the device makes it exclusively available to the VM so the host OS can no longer use it. As I have two Yubikeys, I just configured VMWare to ignore the nano key that’s always plugged in, and pass through the neo when I plug that in. While swapping the configuration around, I found out that GPG remembers the ID of the smartcard that store credentials - if you swap the two keys with identical subkeys it demands the other one is reinserted. You can get rid of the references to the previous card using gpg --delete-secret-keys.

In conclusion…

… I have a new PGP key you can use to verify things I sign or encrypt messages to me.