I think it's time to update your expectations. Hardware security modules have been around for quite a while. You shouldn't assume that your chosen password is the only input to the key derivation, or even that the raw key itself will always be obtainable.
I never assumed that my chosen password was the only input to the key derivation. Just that my chosen password is at least one of the inputs to the key derivation. LUKS has been around for quite a while.
The sane way for encryption keys stored in hardware (secure enclave or tpm like) is to onboard user when the key is not derived from user password. Just like they do for FDE to export a recovery key and then you can adjust your expectations when you know (been told) whats going on.
Yes, that's kind of what you need to be able to successfully back up and restore an encrypted file. Why are you making it sound like that's such a strange thing to want?
No, I'm asking for what LUKS has done for two decades. Keyslots are alternatives, not requirements, so a TPM slot and a passphrase slot coexist and either one alone unwraps the master key.
BitLocker does the same with key protectors. Even on a local account with no internet, there's always a 48-digit recovery password that opens the volume on a completely different machine.
Two of the three major platforms ship a portable passphrase path alongside the hardware one, so this being unavailable here is a product decision, not a law of key derivation.
Comments
I think it's time to update your expectations. Hardware security modules have been around for quite a while. You shouldn't assume that your chosen password is the only input to the key derivation, or even that the raw key itself will always be obtainable.
I never assumed that my chosen password was the only input to the key derivation. Just that my chosen password is at least one of the inputs to the key derivation. LUKS has been around for quite a while.
You're asking for the encryption key to be derivable by an unrelated system that only has the encrypted file and your password.
The sane way for encryption keys stored in hardware (secure enclave or tpm like) is to onboard user when the key is not derived from user password. Just like they do for FDE to export a recovery key and then you can adjust your expectations when you know (been told) whats going on.
Yes, that's kind of what you need to be able to successfully back up and restore an encrypted file. Why are you making it sound like that's such a strange thing to want?
No, I'm asking for what LUKS has done for two decades. Keyslots are alternatives, not requirements, so a TPM slot and a passphrase slot coexist and either one alone unwraps the master key.
BitLocker does the same with key protectors. Even on a local account with no internet, there's always a 48-digit recovery password that opens the volume on a completely different machine.
Two of the three major platforms ship a portable passphrase path alongside the hardware one, so this being unavailable here is a product decision, not a law of key derivation.