3 ms·

Properly secure symmetric encryption needs a key with at least 128 bits of entropy. In the "device lost/stolen" scenario, that key must not be on the device. Ke

Properly secure symmetric encryption needs a key with at least 128 bits of entropy. In the "device lost/stolen" scenario, that key must not be on the device. Key inside a TPM on the device itself is DRM, nothing more. There's better and worse DRM, I think the iPhone bootloader one is one of the better ones, but it's still just DRM. You either need to enter a 128-bit entropy password on every boot (good luck with that) or you need to hold it on some external device, with some variant of USB / smartcard / NFC / Bluetooth to transmit it. NB. this is one of the cases where the usual "key for signing only, never leaves device, ephemeral DH and ZK protocols" like for SSH will not work on its own; you need the high-entropy key physically separate from the device. The NSA realised this a while ago: https://en.wikipedia.org/wiki/KSD-64 https://en.wikipedia.org/wiki/KSD-64 Linux/LUKS etc. doesn't change any of this, by the way. P.S. If Eclipse really has beef with Microsoft, he could always make an exploit that lets you set up a PC without making a Microsoft account.

perching_aix 5mo ago
So much this. Security information should simply never reside on-device in the first place. That said, I think this is a thing with BitLocker? I remember coming across YubiKeys being able to do this via something called PIV (Personal Identity Verification). Found this guide now after giving it a quick search: https://gist.github.com/daemonhorn/03301a66da7d1f4de6cdc8c8bbd171da https://gist.github.com/daemonhorn/03301a66da7d1f4de6cdc8c8b... Not sure how sound of a design it is though, didn't dig into it much at all.
- Borealid 5mo ago
  With PIV, the private keys are stored inside the smartcard (a Yubikey is just one type of smartcard) and don't leave it. They're used for encryption/decryption by the host. Yes, it's generally sound, and is the primary means of authentication and encryption used by the US military for classified systems.
kristjank 5mo ago
Linux+LUKS enables FIDO2, which uses sha256, meets the requirements of "never leaves the device" and keeps it on a separate device, on a separate secure element.

perching_aix 5mo ago

So much this. Security information should simply never reside on-device in the first place. That said, I think this is a thing with BitLocker? I remember coming across YubiKeys being able to do this via something called PIV (Personal Identity Verification). Found this guide now after giving it a quick search: https://gist.github.com/daemonhorn/03301a66da7d1f4de6cdc8c8bbd171da https://gist.github.com/daemonhorn/03301a66da7d1f4de6cdc8c8b... Not sure how sound of a design it is though, didn't dig into it much at all.

Borealid 5mo ago
With PIV, the private keys are stored inside the smartcard (a Yubikey is just one type of smartcard) and don't leave it. They're used for encryption/decryption by the host. Yes, it's generally sound, and is the primary means of authentication and encryption used by the US military for classified systems.

kristjank 5mo ago

Linux+LUKS enables FIDO2, which uses sha256, meets the requirements of "never leaves the device" and keeps it on a separate device, on a separate secure element.