Module slots 

Slot-mapping convention used by this firmware.

Slot allocation is project policy, not a chip primitive. The same chip could be programmed differently. Putting the convention in one place keeps it visible and reviewable.

The authoritative reference is docs/config-zone-layout.md. This module exposes named constants for the slots the service code references; it must stay in sync with the configuration zone the chip is provisioned with.

Slot	Type	Purpose	Policy summary
0	ECC P-256	Primary identity, GenKey-only	ReqAuth=1, AuthKey=5 (PIN-gated). PrivWrite forbidden.
1	ECC P-256	Secondary identity, GenKey-only	Same as slot 0.
2-4	ECC P-256	User keys, GenKey + encrypted import	PIN-gated. Lockable individually.
5	Data 32 B	PIN hash SHA256(PIN || salt)	EncryptWrite via slot 8. LimitedUse via Counter0 (cap 5).
6	Data 32 B	PUK hash SHA256(PUK || salt)	EncryptWrite via slot 8. LimitedUse via Counter1 (cap 10).
7	ECC P-256	User key, GenKey + encrypted import	Same as slots 2-4.
8	Data 32 B	I/O Protection master key	Written pre-data-lock, immutable after. Never written again.
9-15	ECC P-256	Reserve for V2	Same configuration as slots 2-4/7, kept unused for now.

Notes

• Slots 2-4 and 7 all share the same configuration as user-rotatable ECC keys with PIN gating. They are interchangeable from the policy point of view. Project conventions may earmark them for specific roles in the future.
• Slots 9-15 are configured exactly like user slots so they can be used in a later iteration without re-provisioning. Treat them as reserve, do not rely on their contents until a future revision explicitly assigns them.

Constants

PIN_DEFAULT 🔒

Default PIN at factory provisioning. Must be changed on first use.

PIN_MAX_RETRIES 🔒

Size of one PIN batch on Counter0. The “effective tries” available to the user inside a batch is PIN_MAX_RETRIES - 1 (= 4), because refresh_counter_batch lands count one past the next multiple so that count % PIN_MAX_RETRIES == 0 is an unambiguous saturation signal usable by emergency_reset. See service::retries_remaining.

PUK_MAX_RETRIES 🔒

Size of one PUK batch on Counter1. Effective tries inside a batch is PUK_MAX_RETRIES - 1 (= 9), for the same reason as PIN_MAX_RETRIES.

SLOT_IO_KEY 🔒

Slot holding the I/O protection master key.

SLOT_PIN_HASH 🔒

Slot holding the SHA-256 hash of the PIN.

SLOT_PUK_HASH 🔒

Slot holding the SHA-256 hash of the PUK.