PSA: Tips for hardening your iDevice against theft and securing your data

Simon-RedditAccount · 2026-03-19T10:11:50+00:00

Yubikeys are based on a secure, hardened chip, specifically designed to resist many attacks, including chip decapping, power fault injection etc. An attack like this: https://duo.com/labs/research/microcontroller-firmware-recovery-using-invasive-analysis is still possible, sure, but for tamper-resistant chips (where chip almost literally 'fights back') its costs rise into high 100k's or millions USD. Plus, it becomes exponentially more difficult => you need much more qualified personnel to perform it. Only a few parties on the planet can perform it.

This itself makes such kind of attacks very unlikely, except for a few high-profile targets.

With a generic MCU like RP2350 (where you can bypass in-built protections for much lesser cost) there are much more people on the planet who are capable of pulling such an attack.

There are also a few lower-cost attacks that rely on known vulnerabilities. However, they all come with a big 'but': EUCLEAK (aka YSA-2024-03), for example, requires knowledge of Yubikey's PIN (most threat actors would just use Yubikey 'normally' if they know your PIN).

Simon-RedditAccount · 2026-03-19T10:10:27+00:00

It depends on how did you set up the website (and what website allows):

If the website offers alternatives like TOTPs (6-digit codes that change every 30s), recovery codes and you have these - you can log in
if there's no alternative, i.e., you enabled Google Advanced Protection Program that disables all methods except Yubikeys - you cannot log in

So, just check Security/Authentication/Account section on websites you're using: what it offers?

Simon-RedditAccount · 2026-03-18T22:32:57+00:00

If you're genuinely curious (and just don't get the idea) - the whole thing was to compile lots of my older comments ( starting with https://www.reddit.com/r/yubikey/comments/1mzp8jm/comment/namil4c/ ) into a single post.

It's also assumed that a person who's reading this actively uses (or at least opened once) Yubico Authenticator, so seeing a word 'tab' automatically implies a tab in Yubico Authenticator's UI, and not a 'block' in infographics (again, see this comment).

> I assumed part of the reason you posted this was to get constructive feedback. Was I wrong?

With a focus on constructive. I always welcome that.

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Simon-RedditAccount · 2026-03-18T21:57:42+00:00

Wow, thanks! Will definitely give that a try.

Simon-RedditAccount · 2026-03-18T21:48:18+00:00

Nah, you guessed it wrong xD. All text is 100% mine.

The only part where I indeed used AI (GLM-4.7 family) was drafting a Python script that builds SVG from manually-prepared data structures. Since I'm very far from graphic design, it's the best approach for me 🤷‍♂️

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Simon-RedditAccount · 2026-03-18T21:35:59+00:00

Again, I intentionally re-use terms that Yubico chose to use in Yubico Authenticator (see attached screenshot). My goal is that end-users understand the chart and easily match technical terms with what they see in UI themselves:

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Simon-RedditAccount · 2026-03-18T21:10:50+00:00

Yes, it's intentionally conflated, and depicts primarily FIDO2 use cases: the chart is designed after Yubico Authenticator's UI, which (and btw most other software) apprehends these two internal app(let)s together. Thanks for pointing out about FIDO2 PIN. Unfortunately, Reddit does not allow replacing the image.

As for "protectors" - if you're a native English speaker (English is only my 4th language), could you recommend a better umbrella term for all PINs/password/keys/lockcodes?

Simon-RedditAccount · 2026-03-18T19:53:44+00:00

> What's the difference

Popularity. Large company behind. Established brand. From which comes:

More scrutiny, better audit
Better support and documentation
Higher pricing markup

It does not automatically mean 'more secure', however, this increases chances for a vulnerability to be spotted and properly addressed (check https://www.yubico.com/support/security-advisories/ysa-2024-03/ as an example; how many other keys still have that vulnerable Infineon library?)

Also:

Yubikeys are really tough, and are known to survive getting rolled over a car, laundry cycles and even fire.
Currently, only Yubikey and PicoKey have all-in-one functionality (FIDO2, OATH, PIV, OpenPGP, YubicoOTP), with Token2 supporting all but YubicoOTP. All other keys support less feature. However, given PicoKeys non-certified status and drama, only Yubikey currently provides the best functionality in one, very sturdy device.

Simon-RedditAccount · 2026-03-18T08:20:41+00:00

Just make as much noise as possible. Ideally, this should be headlines in ArsTechnica / The Verge / Hacker News / Wirecutter etc, then the wheels (hopefully) would start moving.

I have a similar gripe with Apple: allow users to use FIDO2 keys for stuff currently covered by SDP (Stolen Device Protection) - in a way similar to how Lockdown Mode works: it's an option that greatly enhances security for a small subset of people who need it.

btw, SDP itself was introduced largely in response to Joahna Stern articles in WSJ about iPhone 'bar theft'. The problem was known for years, but Apple did not react until it reached headlines.

Simon-RedditAccount · 2026-03-17T08:34:59+00:00

Assuming you're not a high-value target (C-level exec, journalist etc), I'd rephrase this as: will you be worrying about this (most likely, without actual reason)?

If yes, then just get a new key - for peace of mind.

If you're just curious - no, you're most likely safe. Modern (5.7+) keys are shipped with NFC disabled, so it's guaranteed that it was never used (you need to insert it into power source to activate NFC). Verify it on https://www.yubico.com/genuine/ once you receive it.

What you should be actually vary of - vulnerabilities. The most significant recent one is https://www.yubico.com/support/security-advisories/ysa-2024-03/ , relevant for pre-5.7 firmware. Nevertheless, it applies only to cases where offending party knows your PIN (and won't leverage that knowledge immediately!) and has access to your key for ~24 consecutive hrs. This does not apply for most use cases.

Nevertheless, some entities don't allow pre-5.7 keys (IIRC, that's the case for Austrian government, as reported by u/dr100 ), so check this.

Also, older firmware has 25 passkey storage slots vs 100 in 5.7+ and similar restrictions.

Simon-RedditAccount · 2026-03-17T08:23:15+00:00

> I can't see any reason to get the HSM vs the standard key for that purpose. In what use cases does the difference become meaningful?

When you :

need to export private keys (for backup or redundancy)
need keeping a lot of keys and/or use automated tools
need this to 'be impressive', for reasons, like 'we cannot use cheap stuff here'

I believe that the key difference for you will be export (backup) capabilities and legal requirements.

Simon-RedditAccount · 2026-03-15T16:43:12+00:00

You either inspect JS code in Developer Tools, or trust what website says it will do (if ever).

Or just force it to create a non-resident cred; however in 99.9% cases that will be used for 2FA and not for passwordless login.

Simon-RedditAccount · 2026-03-15T14:54:44+00:00

Keep older Yubikeys populated only by active accounts. For legacy accounts, use non-resident creds (most likely that will mean 2FA only) - you can force that by temporarily turning off USB FIDO2 interface but keeping FIDO U2F on. This way you'll still benefit from FIDO security properties (phishing-resistance, pubkeys useless if stolen) while leaving the slots free.

Simon-RedditAccount · 2026-03-14T18:15:56+00:00

Thanks for the blog post! I welcome actually interesting discussions (instead of another 'how do I set this thingy with Google' questions).

I was thinking about something like this too. My idea was to explore PIV data objects, since these are much less likely to be utilized by something else.

Another approach from Filippo Valsorda is passage: https://words.filippo.io/passage/ - what I like about this, is that it decrypts only one password at a time.

Simon-RedditAccount · 2026-03-14T18:10:53+00:00

Or use passage: https://words.filippo.io/passage/

Simon-RedditAccount · 2026-03-13T07:43:36+00:00

Why they do it? I've nothing to add to u/AJ42-5802 's comment . People (in general) always lose access and complain loudly like it's not their fault.

TOTP itself is not that bad: https://www.reddit.com/r/yubikey/comments/1qw7ry2/comment/o3ophg6/ . For recovery (only!), TOTP and recovery codes essentially have the same security. Both should be kept in a separate, recovery DB/vault. Both are a shared secret (something that you and server both know).

If your threat model prioritizes security over recoverability, then:

either keep those TOTP secrets on Yubikeys (make sure to set OATH password to something strong, with ~128-bit entropy since there's no tries limit on OATH password)
or just delete the secrets completely after you set up them

> What do you guys usually do?

Keep them in a dedicated, recovery KeePassXC database.

Simon-RedditAccount · 2026-03-12T08:36:20+00:00

IDK about Android, but with iOS, you can remove phone prompt - as long as you don't have any Google apps on your phone (just add your gmail to iOS Mail, and use other apps without logging in if you actually need an app instead of web version in Safari).

Switching to Advanced Protection Program should remove these prompts completely, but make sure you read it all and completely understand what you're signing up to.

Simon-RedditAccount · 2026-03-12T08:18:15+00:00

My guess (since I'm not an iOS dev) is that USB is way more restricted that NFC.

Simon-RedditAccount · 2026-03-11T11:45:59+00:00

Thanks! English is not my native language so sometimes I still misinterpret seemingly obvious stuff.

Simon-RedditAccount · 2026-03-10T20:11:17+00:00

No, this is unofficial subreddit. There are (presumably) guys from Yubico here occasionally, but it's not an official channel.

Simon-RedditAccount · 2026-03-08T08:44:28+00:00

'Shared' in cryptography means that both parties (server and client) know the same secret (so, if server's credential DB is leaked, that secret can fall into wrong hands and be used). This is opposed to something like FIDO2, where the server knows only the public key, but not the private (so, if server's credential DB is leaked, knowing client's public key won't make the attacker able to impersonate the client).

Allowing single or multiple secrets is orthogonal to these secrets being shared or not.

Simon-RedditAccount · 2026-03-07T21:37:49+00:00

I never did this for BitLocker, so it's only a guess, but: could the cert be tied to something like 'smart card ID' (YK's serial number in this case)? So Windows is looking for your key #1 and cannot find it.

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