8. Decrypt secrets with a TPM-sealed identity¶

Date: 2026-10-16

Status¶

Accepted

Context¶

sops-nix decrypts with the host's ed25519 SSH host key by default, and since that key sits unencrypted on the OS disk, anyone holding the disk can decrypt every secret encrypted to the host.

age-plugin-tpm generates age identities whose keys are sealed by a TPM and can't be used on any other machine, and every host currently has a discrete TPM.

Decision¶

Each host will decrypt its secrets with an age-plugin-tpm identity, and secrets will be encrypted to those identities instead of to SSH host keys.

Consequences¶

A host's identity is generated on the host itself, and its recipient has to be added to the repo before the host can decrypt anything.

Firmware updates don't affect decryption, since age-plugin-tpm doesn't bind keys to PCRs.