4 ms·

Passkeys really can't be phished because they're site-specific and they can't be stolen because they're kept in the secure enclave. It's worth looking into the

by wmf 3y ago

Passkeys really can't be phished because they're site-specific and they can't be stolen because they're kept in the secure enclave. It's worth looking into the details.

ChuckMcM 3y ago
I'll give you "site specific" but I'm less confident on "can't be stolen." If the computer can fetch them to use them something running on the computer can too. Of course even "site specific" is valuable in the "gmail account" or "apple ID" world. The last Kreb's article was something like $30 each for gmail creds. Also my computer doesn't have a secure enclave because I'm keeping it disabled to prevent my machine from upgrading to Windows 11 :-). I wonder what it would try to do in that case. That said, are people putting their cryptowallets in the secure enclave too these days? That would be new information for me.
- obpe 3y ago
  The key isn't fetched and never leaves the enclave. The enclave does the crypto functions. Passkeys are meant to replace passwords for the average user. And they definitely succeed at that.
  - ChuckMcM 3y ago
    So in order to access a service your access device has to have a secure enclave that can enact this crypto?
    - tony-allan 3y ago
      Most modern devices do contain a hardware based Secure Enclave. Because the technology is newish I would do some research before using it for anything really important.
      - jruohonen 3y ago
        > Most modern devices do contain a hardware based Secure Enclave. So like Intel's SGX was so secure until it was not?
        wmf 3y ago
        You have to start somewhere.
        sp332 3y ago
        If my setup is secure enough that someone has to break SGX on my laptop to beat it, that's good enough for me. What is your threat model anyway?
    - sp332 3y ago
      It depends on the implementation, but I think that's the general idea. https://developer.android.com/privacy-and-security/keystore https://developer.android.com/privacy-and-security/keystore for Android, for example.
    - justinludwig 3y ago
      Or you can use an external hardware security key; the latest versions of most security keys (like YubiKey 5, Nitrokey 3, etc) support Passkeys. Passkeys are basically just U2F 2.0, allowing you to use an asymmetric key pair as the first factor instead of the second.
      - ChuckMcM 3y ago
        Thanks for that, Yubikey notes that you cannot copy passkeys (this is good!), but now I'm wondering if I can have multiple passkeys (for a backup key)...
        m-p-3 3y ago
        That's up to each services to implement, but so far all the sites I use with Passkeys have my two Yubikeys registered.
  - richardjam73 3y ago
    What if you use multiple different devices? How can they share the key?
    - echeese 3y ago
      You can add passkeys for each device (e.g. Windows Hello) or use cloud-synced keys (iCloud, Google, 1Password, probably more)
lapcat 3y ago
> they're kept in the secure enclave. No, they're not. It is indeed worth looking into the details. It would be impossible to sync passkeys, for example via iCloud keychain, if they were kept in the secure enclave.
- wmf 3y ago
  I forgot that Apple is syncing passkeys but my understanding is that iCloud sync is enclave-to-enclave (unless you have an old Mac I guess) which is just as secure.
  - lapcat 3y ago
    > my understanding is that iCloud sync is enclave-to-enclave (unless you have an old Mac I guess) You misunderstand. Keys that are stored in the secure enclave never get out. They can't get out. That's literally why it's secure. This is why Apple silicon Mac internal hard drives can no longer be swapped. If the drive is separated from the secure enclave, or the secure enclave is damaged and the encryption key is lost, the data on the hard drive can't be recovered. You don't have the key; you can't get the key.
    - wmf 3y ago
      So you're saying what... passkeys don't use the enclave at all?
      - lapcat 3y ago
        There are synced passkeys, and there are device-bound passkeys. The OP mentions Yubikey: you can store a passkey on a Yubikey, and then it's device-bound and can't be exported. But Apple's implementation of passkeys is synced; they're just stored in an encrypted keychain.
    - md_ 3y ago
      I think you're the one who misunderstands. Synced Passkeys are, in the Apple world, still stored in a Secure Element; they just are exportable. https://www.slashid.dev/blog/passkeys-deepdive/ https://www.slashid.dev/blog/passkeys-deepdive/ describes this fairly clearly. Syncing does certainly open up attacks that are not possible against non-synced credentials, but you're incorrect to say that synced Passkeys are not stored in the Secure Element. At least, that's my understanding. Tell me if I'm wrong!
solardev 3y ago
My passkeys just live in the 1Password cloud and get synced everywhere. Nothing to do with my computer. We went from "something you know, something you own, something you are, choose two" to "something only they know, choose one". Shrug. Sure is convenient though.
eviks 3y ago
Password manager can generate site-specific keys (and as noted in the comments, they're not stored in the enclave)

by wmf 3y ago

Passkeys really can't be phished because they're site-specific and they can't be stolen because they're kept in the secure enclave. It's worth looking into the details.

ChuckMcM 3y ago

I'll give you "site specific" but I'm less confident on "can't be stolen." If the computer can fetch them to use them something running on the computer can too. Of course even "site specific" is valuable in the "gmail account" or "apple ID" world. The last Kreb's article was something like $30 each for gmail creds. Also my computer doesn't have a secure enclave because I'm keeping it disabled to prevent my machine from upgrading to Windows 11 :-). I wonder what it would try to do in that case. That said, are people putting their cryptowallets in the secure enclave too these days? That would be new information for me.

obpe 3y ago
The key isn't fetched and never leaves the enclave. The enclave does the crypto functions. Passkeys are meant to replace passwords for the average user. And they definitely succeed at that.
- ChuckMcM 3y ago
  So in order to access a service your access device has to have a secure enclave that can enact this crypto?
  - tony-allan 3y ago
    Most modern devices do contain a hardware based Secure Enclave. Because the technology is newish I would do some research before using it for anything really important.
    - jruohonen 3y ago
      > Most modern devices do contain a hardware based Secure Enclave. So like Intel's SGX was so secure until it was not?
      - wmf 3y ago
        You have to start somewhere.
      - sp332 3y ago
        If my setup is secure enough that someone has to break SGX on my laptop to beat it, that's good enough for me. What is your threat model anyway?
  - sp332 3y ago
    It depends on the implementation, but I think that's the general idea. https://developer.android.com/privacy-and-security/keystore https://developer.android.com/privacy-and-security/keystore for Android, for example.
  - justinludwig 3y ago
    Or you can use an external hardware security key; the latest versions of most security keys (like YubiKey 5, Nitrokey 3, etc) support Passkeys. Passkeys are basically just U2F 2.0, allowing you to use an asymmetric key pair as the first factor instead of the second.
    - ChuckMcM 3y ago
      Thanks for that, Yubikey notes that you cannot copy passkeys (this is good!), but now I'm wondering if I can have multiple passkeys (for a backup key)...
      - m-p-3 3y ago
        That's up to each services to implement, but so far all the sites I use with Passkeys have my two Yubikeys registered.
- richardjam73 3y ago
  What if you use multiple different devices? How can they share the key?
  - echeese 3y ago
    You can add passkeys for each device (e.g. Windows Hello) or use cloud-synced keys (iCloud, Google, 1Password, probably more)

lapcat 3y ago

> they're kept in the secure enclave. No, they're not. It is indeed worth looking into the details. It would be impossible to sync passkeys, for example via iCloud keychain, if they were kept in the secure enclave.

wmf 3y ago
I forgot that Apple is syncing passkeys but my understanding is that iCloud sync is enclave-to-enclave (unless you have an old Mac I guess) which is just as secure.
- lapcat 3y ago
  > my understanding is that iCloud sync is enclave-to-enclave (unless you have an old Mac I guess) You misunderstand. Keys that are stored in the secure enclave never get out. They can't get out. That's literally why it's secure. This is why Apple silicon Mac internal hard drives can no longer be swapped. If the drive is separated from the secure enclave, or the secure enclave is damaged and the encryption key is lost, the data on the hard drive can't be recovered. You don't have the key; you can't get the key.
  - wmf 3y ago
    So you're saying what... passkeys don't use the enclave at all?
    - lapcat 3y ago
      There are synced passkeys, and there are device-bound passkeys. The OP mentions Yubikey: you can store a passkey on a Yubikey, and then it's device-bound and can't be exported. But Apple's implementation of passkeys is synced; they're just stored in an encrypted keychain.
  - md_ 3y ago
    I think you're the one who misunderstands. Synced Passkeys are, in the Apple world, still stored in a Secure Element; they just are exportable. https://www.slashid.dev/blog/passkeys-deepdive/ https://www.slashid.dev/blog/passkeys-deepdive/ describes this fairly clearly. Syncing does certainly open up attacks that are not possible against non-synced credentials, but you're incorrect to say that synced Passkeys are not stored in the Secure Element. At least, that's my understanding. Tell me if I'm wrong!

solardev 3y ago

My passkeys just live in the 1Password cloud and get synced everywhere. Nothing to do with my computer. We went from "something you know, something you own, something you are, choose two" to "something only they know, choose one". Shrug. Sure is convenient though.

eviks 3y ago

Password manager can generate site-specific keys (and as noted in the comments, they're not stored in the enclave)