TPM isn’t all that reliable. You will have people upgrading their pc, or windows update updating their bios, or any number of other reasons reset their tpm keys, and currently nothing will happen. In effect people would see Signal completely break and loose all their data, often seemingly for no reason.
Talking to windows or through it to the TPM also seems sketchy.
In the current state of Windows, the sensible choice is to leave hardware-based encryption to the OS in the form of disk encryption, unfortunate as it is. The great number of people who loose data or have to recover their backup disk encryption key from their Microsoft account tells how easily that system is disturbed (And that Microsoft has the decryption keys for your encrypted date).
TPM isn’t all that reliable. You will have people upgrading their pc, or windows update updating their bios, or any number of other reasons reset their tpm keys, and currently nothing will happen. In effect people would see Signal completely break and loose all their data, often seemingly for no reason.
Talking to windows or through it to the TPM also seems sketchy.
In the current state of Windows, the sensible choice is to leave hardware-based encryption to the OS in the form of disk encryption, unfortunate as it is. The great number of people who loose data or have to recover their backup disk encryption key from their Microsoft account tells how easily that system is disturbed (And that Microsoft has the decryption keys for your encrypted date).