Hands-on with the YubiKey 4C

It may not look like it, but almost two years (April 10, 2015) have passed since Apple’s aggressively entered the USB-C family with the launch of its new laptop, the MacBook 12", which had a single USB-C port. A year later, a second generation MacBook was launched with the exact same port layout, confirming Apple’s bet on the new USB standard. In the meantime, the market was flooded with a myriad of new laptops and accessories with USB-C compatibility coming from several other reputable brands.

It took almost a year since the launch of the first MacBook with USB-C for Yubico to recognize enough demand for a USB-C version of its popular YubiKey product line. The demand didn’t appear to be that high though, as the official solution presented by Yubico in July of 2016 was nothing more than a USB-A to USB-C mini adapter bundled together with a lanyard and the YubiKey 4 Nano.

Yubico’s USB-C mini adapter could not be bought separately and the bundle cost only $1 more than the YubiKey 4 Nano sold separately. The adapter was not particularly attractive and it was actually very similar to other aftermarket parts. It didn’t look like Yubico was really betting on USB-C. On their blog post YubiKey and the Route to USB-C they basically say that a number of USB-C adapters were tested and confirmed working with the YubiKey.

Multiple USB-C mini adapters shown with the YubiKey 4 Nano inserted. Source: Yubico

It was also the first time that they mentioned that a prototype USB-C product was being worked on and that perhaps NFC could make it less important or even obsolete.

Fast forward to November, 2016 and the world sees Apple announcing the first MacBook Pro laptops exclusively with USB-C ports after a much antecipated line-up refresh - and guess what? No NFC. Back then, if Yubico had any doubt that its prototype would need to enter mass production, it was all gone since. Demand was about to reach new highs and a USB-C mini adapter would no longer be acceptable for its customers.

Just shy of two months and Yubico was announcing its first USB-C product - the YubiKey 4C - unveiled at the forefront of the technology world, CES 2017.

The new YubiKey 4C

The YubiKey 4C is built on the foundation of the YubiKey 4, so it offers the same protocol support as its siblings, namely Yubico OTP, OATH, FIDO (U2F), OpenPGP with RSA 4096 and PIV with RSA 2048 + ECCP384.

I was lucky enough to get my hands on a preproduction unit of the YubiKey 4C to put it under test. The final unit may look slightly different.

The YubiKey 4C standing on a table.

The YubiKey 4C is extremely well built. It’s very light (weighs just 2 grams!), compact (29.5 mm x 12.5 mm x 5.5 mm), sturdy and elegant. It is made of a soft plastic finish and three gold-colored metal contacts: two on each side of the key plus a rounded one in the center of the key ring.

The fitting on any USB-C port I’ve plugged it into was seamless which resulted in a solid piece of hardware that didn’t wobble even when shaking the computer it was connected to. The final movement had a punchy feeling, which usually is a sign of a high quality connector.

The YubiKey 4C inserted into a MacBook Pro 13" with Touch Bar. The fit is perfect.

However, the YubiKey 4C has a visible seam on its connector. Folded metal (which is what produces the visible seam) tends to be more fragile than a single piece of metal, which may or may not be a concern on the 4C depending on the choice of metal. Since it won’t be plugged in at all times, it’s likely to be carried around a keychain in your pocket. Strength is important here to avoid accidental bending.

When questioned about the seam, Yubico stated that "[…] our plugs do have a seam, and I’d say all plugs that are not designed to be a part of a cable assembly are done that way. In a cable assembly, the metal jacket is more like a tube, whereas our device has a plug that is attached to a circuit board. The later is an intricate cut-and-fold operation of sheet metal, hence the need for a seam."

Yubico is definitely aware of this but I trust them when it comes to quality, so the seam won’t likely be a problem.

A bird’s view on the YubiKey 4C where the seam is noticeable.

The 4C is so compact that it makes a regular YubiKey 4 look like an ancient piece of hardware, especially because it supports all features of its older sibling. It carries great in your pocket and its distinguishable form makes it very easy to grab if a lanyard is not used.

It’s not slim enough to be carried inside a card wallet like the one below but it’s comfortable enough to carry around your pocket or keychain.

A slim wallet side to side the YubiKey 4C.

Having the metal contacts on both sides of the key allows triggering touch actions with no complications. The touch detection has a small delay (in the order of hundreds of milliseconds) which I believe to be something premeditated as it lowers the risk of accidental touch. While I don’t have any scientific data on this, it appears to be a little more optimized when compared to the YubiKey 4 Nano.

The slim profile of the YubiKey 4C has it’s problems though - removing the key from your laptop will almost certainly trigger an action as the key must be pulled exactly where the metal contacts are. On a MacBook Pro 13" with Touch Bar, the laptop is so thin that there isn’t any other alternative to grab the key unless you’re ok with using something else to pull it via the key ring.

Profile of the YubiKey 4C.

Being USB-C also means you won’t have that awkward moment of trying to find the right position to enter the key into your computer. Reversibility is truly awesome.

The 4C isn’t going to be the always plugged-on key that the Nano can be but Yubico said it’s working on a smaller YubiKey form factor with a USB-C design similar to the Nano, with no time frame available at the moment of writing.

In terms of software, the 4C is expected to be loaded with at least firmware version 4.3.3 and behave exactly like the other members of the YubiKey 4 series. For an in-depth review of most YubiKey features, be sure to checkout my Yubikey Handbook.

YubiKey Personalization Tool with the YubiKey 4C inserted.

The YubiKey, now in it’s USB-C form, remains a little, fascinating and powerful device. It’s available for purchase on February 13th at the Yubico Online Store ($50 USD).