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What I Wish I Knew About U2F and Other Hardware MFA Protocols

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Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#81

Post by gnufx »

OJFord wrote: post #77
Arnavion wrote: post #68

Earlier quoted context omitted.

I also don't know why the author thinks HSMs cost "hundreds to tens of thousands of dollars". In the first place, TPMs are a subcategory of HSMs and don't cost that much. In the second place, HSMs like the Microchip ATECC608B cost <$1 for the bare board.

OP says devices , so I read rack-mount gear that you buy when you can't use (or trust) AWS KMS, not chips.

Not yet implemented, but Solo 2 has a "stretch goal" to provide HSM functionality, if that would be good enough. https://www.indiegogo.com/projects/solo-v2-safety-net-agains...

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#82

Post by gnufx »

mPReDiToR wrote: post #75
christiansakai wrote: post #8

For a noob like me, I am thinking to get a Yubikey. What will happen if I lose my Yubikey? Am I essentially out of luck assuming the admins can’t reset my password or associated yubikey device? How do I prevent such scenario from happening? Is there truly a fool proof way of hardware authentication?

I tried YubiKey and SoloKey (OSS). I've settled on OnlyKey ( https://crp.to ) because it's OSS and you can back it up and restore. Backup can be GPG encrypted. 24 slots, programmable to store URL, U/N, P/W, 2FA, with the ability to click the address bar in a browser, hit a key on the OnlyKey and watch as it types it all in without any other interaction. It stores MANY types of auth. Not affiliated, but a very happy u…

OnlyKey's features are attractive, but its implementation has been questioned. https://news.ycombinator.com/item?id=21884184

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#83

Post by tomatocracy »

userbinator wrote: post #65
exporectomy wrote: post #13

Earlier quoted context omitted.

For services where no admin can get your access back, like most websites, a 3rd factor should be a compulsory part of 2FA. There's a balance between keeping hackers out and keeping yourself out. The more factors you require, the more optional factors you should also require users to have, not just optional codes but "you must write these codes down, we'll check later to make sure you did" or something like that.

not just optional codes but "you must write these codes down, we'll check later to make sure you did" or something like that. ...which people will still not do, or misplace/erase due to disuse, etc. Security and availability are always at odds with each other. The question that you should always have when choosing a level of security is "does the risk of denying everyone access --- including myself --- outweigh the r…

Isn't minimising the "I lost them/forgot where I put them" scenario the point of checking you still have them (not just asking - checking eg by saying "enter one of the codes")? That way, if you don't have them, you can print a new set of backup codes while you still have your "normal" second factor to hand.

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#84

Post by throwmeaway1717 »

sly010 wrote: post #49
thatnerdyguy wrote: post #27

Earlier quoted context omitted.

That's all well and good, but a few weeks later I have another service I'm going to sign up for... I have to... first go to my safe deposit box to grab my third key? If I don't, then seems like it's a lot of bookkeeping.

Needless to say, I don't use these devices on my home depot account. I use them for Google, Github, Dropbox, I don't actually remember anything else. My DNS registrar doesn't support it :P I also don't use my personal key for work stuff and recovering my work key is my sysadmins problem :) That said, when I had admin accounts at work, we used TOTP with a similar scheme: when we registered important (admin) accounts w…

My DNS registrar does - https://gandi.net

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#85

Post by TacticalCoder »

ranma42 wrote: post #74
TacticalCoder wrote: post #4

From TFA: > Since the U2F device creates and stores asymmetric key pairs, and is able to sign arbitrary “challenges”, can I use it as a general-purpose hardware key store? You can however do it "the other way round" and use a private key to derive a U2F path. And that same private key can be used for many other applications (or none). For example you can use the Ledger Nano S (originally a cryptocurrencies hardware w…

> you can reinitialize your Nano S as a new U2F device According to the yubico explanation linked from article, U2F includes cloning protection (an authentication counter, which the site should check has increased vs. its last known value), so that might not actually work if the site you are authenticating against is well-implemented (Unless the Nano S also lets you back up the counter value).

> ... so that might not actually work if the site you are authenticating against is well-implemented

I'm using it on several sites and already did swap / reinitialize my U2F devices... It works, including on GMail. As I understand it the most recent Webauthn is going to be supported by Ledger soon.

I don't think they're non-compliant or badly implemented websites: although I'm not sure what the specs say.

I do personally love that I can back up my "seed" and know that by going to pick my safe at the bank I'll always be able to reinitialize an U2F device and I'll also really love that it displays "Google" on the Ledger Nano S's tiny screen.

Pricey little thing to use as "only" an U2F device: about 60 USD but I like it a lot.

> (Unless the Nano S also lets you back up the counter value)

Late reply but... As I understand it as long as the counter is monotonic it'll always work. What Ledger does (and apparently the Trezor too from reading this thread, another device with an HSM) is, upon initializing the U2F app the first time on your hardware device, is to set the counter to the current timestamp.

So basically: once you use another device to log in, then you cannot use the old one, unless you reinitialize it (and then it's the other you cannot use, unless you reinitialize it etc.). These devices do not have a clock, which is why it works that way (in the case of the Ledger Nano S / Ledger Nano X at least).

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#86

Post by TacticalCoder »

diggernet wrote: post #32
christiansakai wrote: post #8

For a noob like me, I am thinking to get a Yubikey. What will happen if I lose my Yubikey? Am I essentially out of luck assuming the admins can’t reset my password or associated yubikey device? How do I prevent such scenario from happening? Is there truly a fool proof way of hardware authentication?

I've been troubled by that question too. Especially since I've heard people complain about sites that only allow registering one key. But TacticalCoder just said something really interesting in another part of this conversation: > you can use the Ledger Nano S with your "seed" (say a 256-bit secret, stored as 24 words you hide), to log in sites using U2F. > Additionally as long as you've got your secret, you can rein…

> If I read that right, some keys rather than having a hardcoded unique seed, will let you set your own.

Set your own or generate one for you, using an hardware CSPRNG, and then let you write it down in a convenient way (24 words out of a dictionary of 2048 words, so 264 bits: 256 bits of entropy plus 8 bits of checksum. Heck, you can use 12 or 18 words too. I think the (BIP39 / BIP44) standard even allows for 15 words but Ledger does only support lists of 12/18 and 24 words although don't quote me on that).

> Which implies you can have multiple functionally-identical backup keys locked up securely somewhere.

I don't even bother having multiple devices ready to use. I simply store the seed (once again: as a list of 12/18 or 24 words) on a sheet of paper and I store this in vaults/safes.

> Anyone know which keys support this (aside from the mentioned Nano S and Trezor)? What's the magic keyword to look for in specs?

I've got a Ledger Nano S only for this. It's really a nice little device. I don't work for Ledger btw! They're a bit pricey but, indeed, the anxiety of getting locked out of your account or having through crazy procedures goes away.

It's a pricey little device but not that crazy expensive: about 60 USD I think.

> What's the magic keyword to look for in specs?

I don't know but the U2F "nano app" does work with Google and other sites and I know that Ledger is working on the more recent Webauthn support.

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#87

Post by Arnavion »

OJFord wrote: post #77
Arnavion wrote: post #68

Earlier quoted context omitted.

I also don't know why the author thinks HSMs cost "hundreds to tens of thousands of dollars". In the first place, TPMs are a subcategory of HSMs and don't cost that much. In the second place, HSMs like the Microchip ATECC608B cost <$1 for the bare board.

OP says devices , so I read rack-mount gear that you buy when you can't use (or trust) AWS KMS, not chips.

Well, I don't know if they really meant rack-mount gear, but sure it costs a little extra to get it usable with a general-purpose computer.

Specifically, you can get that Microchip HSM in a form factor that plugs into a click shield, then plug the click shield into a Raspberry Pi's GPIO pins. You now have a PKCS#11-usable HSM from a Pi. Including the click shield still puts the cost at (I have a few such setups lying around because my $dayjob includes a PKCS#11-consuming application that runs on such setups.)

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#88

Post by Rafert »

shaicoleman wrote: post #52
jrockway wrote: post #40

Earlier quoted context omitted.

U2F is the predecessor to the current standard, WebAuthn. If a web app supports WebAuthn, then that integrates with native keystores (Windows Hello, Face ID, whatever Android has), as well as hardware keys. The site operator has some flexibility to prefer certain methods (platform vs. external) and devices (attestation). I wrote an authenticating proxy that uses Webauthn: https://github.com/jrockway/jsso2 . I don't t…

Unfortuately WebAuthn with the native keystores requires Bluetooth, which is a constant source of pain. That's a deal-breaker for me.

I think you're confusing the cloud-assisted Bluetooth (caBLE) transport with actual built-in device keystores. Google is testing this on their properties while it's being standardized in CTAP and WebAuthn, see https://github.com/w3c/webauthn/issues/1381

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#89

Post by EvanAnderson »

OJFord wrote: post #77
Arnavion wrote: post #68

Earlier quoted context omitted.

I also don't know why the author thinks HSMs cost "hundreds to tens of thousands of dollars". In the first place, TPMs are a subcategory of HSMs and don't cost that much. In the second place, HSMs like the Microchip ATECC608B cost <$1 for the bare board.

OP says devices , so I read rack-mount gear that you buy when you can't use (or trust) AWS KMS, not chips.

I implemented a firmware signing infrastructure for a large embedded hardware manufacturer using USB Nitrokey HSM devices (sub-$100/ea). We got the functionality we wanted from them at a fraction of the price point of the "big name" HSM manufacturers' offerings. The development effort to integrate the Nitrokey HSM, as a simple PKCS#11 device, was very simple. What we could get of the big-name HSM manufacturers' development docs, w/o an NDA or a purchase, looked to be much more difficult to integrate.

Re: What I Wish I Knew About U2F and Other Hardware MFA Protocols

#90

Post by mPReDiToR »

gnufx wrote: post #82
mPReDiToR wrote: post #75

Earlier quoted context omitted.

I tried YubiKey and SoloKey (OSS). I've settled on OnlyKey ( https://crp.to ) because it's OSS and you can back it up and restore. Backup can be GPG encrypted. 24 slots, programmable to store URL, U/N, P/W, 2FA, with the ability to click the address bar in a browser, hit a key on the OnlyKey and watch as it types it all in without any other interaction. It stores MANY types of auth. Not affiliated, but a very happy u…

OnlyKey's features are attractive, but its implementation has been questioned. https://news.ycombinator.com/item?id=21884184

I'm not sure I come away from that discussion with less confidence.

The dev managed to answer everything put to them with alacrity. The question of code quality was of no consequence as even ugly code can work, and it's got more eyes on it than closed source.

In my threat theatre this device is far more than adequate for securing GitHub, GOOG, and a couple of GPG/ssh keys.

Should I ever becaome a spy, I'll probably revert to speaking to strangers about how red sparrows fly at certain times of day again.

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