Favilla KEY treats your two identities differently, because they carry different risk.
Your Nostr identity key lives wrapped inside the SE051 itself. When you sign an event, the key is unwrapped inside an authenticated PIN session, the Schnorr signature is computed on the ESP32, then the key is wiped from memory. The window is milliseconds.
Your Bitcoin seed is stored as an AES-encrypted blob in the ESP32's flash, encrypted under a key that lives inside the SE051 and is only usable once your PIN has unlocked a session on the chip. A flash dump returns ciphertext. Miss the PIN, or remove the device, and nothing can be reconstructed.
The NXP SE051 is a Common Criteria EAL 6+ certified secure element, the same class of chip used in payment cards and passports. Your PIN is verified inside the silicon against a hardware auth object with a brute-force retry counter, never against a value in the firmware. ECDH for NIP-44 DM key agreement runs on-chip. The ESP32 adds flash encryption burned into one-time fuses at manufacture, so the storage chip itself returns only ciphertext.
We're deliberately precise about one thing competitors often blur: the SE051 has no native BIP-340 Schnorr, so signing happens on the ESP32, not inside the secure element. The key material is briefly present in RAM during a signature, then wiped. The secure element guards every key at rest and gates every release behind a PIN session; the device minimises how long anything sensitive is exposed. On-chip Schnorr signing, where keys never enter main memory at all, is a roadmap goal bounded by what the silicon supports.
Keys sealed in the secure element at rest. Brought into memory only for the instant of a signature, then wiped. Your PIN gates every release.
