Server Key

Since Hyphen's multi-sig always requires at least two keys (2 of N), if a user account only has a device key, there is the inconvenience of having to do 2FA every time signing a transaction. To solve this UX issue, we store a key on the Hyphen server called the Server Key (a.k.a. Custodial Key).

The Server Key has an attribute called Auto-Sign. When signing a transaction with the Hyphen SDK, the Hyphen server always provides a Server Key signature. Therefore, from the user's perspective, they can secure two signatures— the current device key signature + server key signature— which means they can send transactions without 2FA under normal circumstances.