I believe with software-based encryption (LUKS and the like), the decryption key ends up being stored in RAM, which will always present a risk.
And TPM-based solutions don't have this problem. Could be wrong though.
And TPM-based solutions don't have this problem. Could be wrong though.
I believe when using TPM with LUKS the TPM just decrypts the master key and that is handed back to the OS and used in software. So the primary key does end up in RAM.