[Cu3PO42]

The important part in the parent is "that don't need a user password". You just said you had to supply a (user) password.

With a TPM you can set it up that your disk is unlocked automatically, but only if no-one changed anything in the signed boot chain. This is the default with Bitlocker on Windows and is also possible on Linux, though somewhat more finicky.

[beeflet]

but why bother? I can fit enough entropy in my head to make my hard drive uncrackable, and I can back up my data even if some chip breaks.

It's just added complexity and corporate control so people can use worse passwords

[repiret]

But most people don't want to enter a password, and if you make people enter a password too much, they'll choose terrible passwords and put them on a sticky note. Windows Hello can only be done securely with a TPM. A server that I want to turn back on all by itself after a power outage can only be done securely with a TPM.

I want a TPM in my computer so I can have the security and convenience. Yes, it's another point of failure. But I need backups in case the hard drive fails anyway. And besides, the OS can be designed so I can enter a password if I need to use the drive without the TPM.

[edg5000]

But without password, anybody can physically access the device and exfiltrate data. That is even easier than regular password protection, where the storage medium would have to be removed or a live OS would have to be booted.

The risk is data leakage. With a TPM and no password, there is no data leakage protection.

[repiret]

Passwordless boot with a TPM means the software can control what secrets it gives out. Yeah, if you boot to a desktop operating system and auto-login as an admin user, that doesn't leave things very secure, but that's not the only scenario.

Consider a server. It can have an encrypted hard drive, boot with the TPM without a password, and run its services. In order to steal data from it, you need to either convince software running on the server to give you that data, or you need to do some sort of advanced hardware attack, like trying to read the contents of DRAM while the computer is running.

There are other use cases too, like kiosks, booting to a guest login, corporate owned laptops issued to employees, allowing low-entropy (but rate limited) authentication after booting, to name a few.