TPM 2.0 keyslots

Bind a vault to the local machine's TPM. Optional PIN, fused TPM + FIDO2, hybrid TPM + post-quantum.

A TPM 2.0 keyslot binds the vault to the specific TPM chip in the machine where you enroll it. The chip seals the wrap-KEK against its own endorsement seed; the seed never leaves the chip and is re-derived deterministically on every operation. The vault opens on that machine; it does not open on any other machine, even with the same passphrase or FIDO2 device.

TPM 2.0 keyslots work on Linux and Windows (Windows since v0.5.0). On Windows the chip is reached through TBS (TPM Base Services), the broker built into every supported Windows, so no driver, admin rights, or code signing are needed to seal or unseal. macOS does not expose a TPM, use a Secure Enclave keyslot there instead (since v0.4.0). Slot bytes are byte-identical across platforms: the same physical chip unseals a vault regardless of which OS sealed it. The .lbx file itself stays portable everywhere; only the TPM slot is bound to one chip.

When to use a TPM slot

You want	Use
Unlock without a hardware key on the daily-use machine	TPM (no PIN) + a passphrase backup
Hardware-bound + something the user knows	TPM + PIN
Two-factor "must have YubiKey AND must be on this machine"	Fused TPM + FIDO2 (single slot, both required)
Post-quantum on top of TPM binding	Hybrid TPM + ML-KEM-768 / 1024
All of the above	Hybrid TPM + FIDO2 + ML-KEM-768 / 1024

Always pair a TPM slot with a backup slot. A TPM keyslot becomes permanently unrecoverable if:

The chip is replaced (motherboard swap, device wipe at firmware level).
You move the vault to another machine.
The TPM is cleared by firmware reset.

The CLI / GUI / wizard all surface a warning before creating a TPM-only vault.

Variants

Slot kind	Inputs at unlock	Notes
`Tpm2Sealed`	TPM only	Plain TPM seal; no PIN. Binds to chip + boot policy (no PCR sealing yet).
`Tpm2SealedPin`	TPM + PIN	TPM `userAuth` is the PIN. Wrong PINs count toward the chip's dictionary-attack lockout (typically about 32 attempts then a multi-hour cooldown), so even short PINs are practical.
`Tpm2Fido2`	TPM + FIDO2 hmac-secret (fused)	Single slot, both factors required; HKDF mixes TPM-unsealed value with FIDO2 hmac-secret.
`HybridPqKemTpm2`	TPM + ML-KEM-768 decap	Hybrid PQ on top of TPM binding.
`HybridPqKem1024Tpm2`	TPM + ML-KEM-1024 decap	Same with category-5 KEM.
`HybridPqKemTpm2Fido2`	TPM + FIDO2 + ML-KEM-768 decap	Three-factor + PQ.
`HybridPqKem1024Tpm2Fido2`	TPM + FIDO2 + ML-KEM-1024 decap	Strongest TPM-bound option.

Linux: TPM access without root

Unprivileged users need read/write access to /dev/tpmrm0 (the in-kernel resource manager). Three things have to be true:

The tss system group exists.
/dev/tpm0 / /dev/tpmrm0 are owned root:tss with mode 0660 (this is what the udev rule does).
Your user is a member of the tss group.

The .deb (since v0.2.0) Recommends tpm-udev which provides (1) + (2). The .rpm Recommends tpm2-tss which does the equivalent on Fedora / RHEL / openSUSE. Installing via apt / dnf gets both for you by default. You then only have to do (3) yourself, Debian / Fedora convention forbids silent privileged- group additions in package scripts:

sudo usermod -aG tss "$USER"
# Log out and back in (or `newgrp tss`) for the new group to take
# effect in your shell session.
id | tr , '\n' | grep tss   # confirm
ls -l /dev/tpmrm0           # expected: crw-rw---- 1 root tss ...

If you installed via the tarball, or passed --no-install-recommends / --setopt=install_weak_deps=False, neither the group nor the udev rule exists. Use the bundled installer:

./install.sh --tpm-setup     # creates the group + udev rule + adds you

Or do it by hand:

sudo groupadd --system tss
sudo usermod -aG tss "$USER"
sudo tee /etc/udev/rules.d/60-tpm.rules > /dev/null <<'EOF'
KERNEL=="tpm[0-9]*",   MODE="0660", GROUP="tss"
KERNEL=="tpmrm[0-9]*", MODE="0660", GROUP="tss"
EOF
sudo udevadm control --reload-rules
sudo udevadm trigger
# Log out + back in.

Verify:

tpm2_getrandom --hex 8     # if you have tpm2-tools installed
luksbox info my.lbx        # should not error on TPM slots

The full playbook with troubleshooting is in docs/TPM_LINUX_PERMISSIONS.md.

Windows: TPM access needs no setup

On Windows the chip is reached through TBS (TPM Base Services), the system broker present on every supported Windows. There is no group to join, no udev rule, and no admin elevation: a normal user process seals and unseals directly. Windows 11 hardware ships a TPM 2.0 chip by default (part of the launch floor); on a VM, enable the virtual TPM in your hypervisor (Hyper-V, VMware, VirtualBox all expose one).

# Confirm the chip is present and ready
Get-Tpm

# Create a TPM-bound vault (same slot kinds as Linux)
luksbox create my.lbx --kind tpm2
luksbox create my.lbx --kind tpm2-pin

If a TPM operation reports the chip is locked out, reset the lockout from an elevated PowerShell (do NOT run Clear-Tpm, which wipes the owner hierarchy and permanently destroys every TPM slot in your vaults). A vault sealed on Windows unseals on Linux through the same physical chip, and vice versa.

CLI, create a TPM-bound vault

# Plain TPM (no PIN)
luksbox create my.lbx --kind tpm2

# TPM + PIN
luksbox create my.lbx --kind tpm2-pin

# Fused TPM + FIDO2 (both required to unlock)
luksbox create my.lbx --kind tpm2-fido2

# Hybrid TPM + ML-KEM-768
luksbox create my.lbx --kind hybrid-pq-tpm2 \
    --pq-hybrid /media/usb/my.kyber

# Strongest: hybrid TPM + FIDO2 + ML-KEM-1024
luksbox create my.lbx --kind hybrid-pq-tpm2-fido21024 \
    --pq-hybrid /media/usb/my.kyber

After create, the wizard / GUI offer to add a backup keyslot. The CLI emits the same warning and asks you to confirm. To enroll a backup later:

luksbox enroll my.lbx --kind passphrase

TUI / GUI

The interactive wizard and the GUI create flow both expose every TPM variant through the same factor-then-variant picker. The GUI's recent-vaults list shows a TPM-binding badge so you know which vaults are machine-bound before you try to open them on a different host.