The Master Key is created once, the root of the identity.

• Used to derive the Identity Root:

  identity_root = H(
    master_key_public,
    namespace,
    creation_time
  )
  
  

• Stored in the most secure context (HSM / hardware wallet / specialized secure device)

• Rarely used directly

• Normally only needed for:

  • creating the identity
  • authorizing protocol-level changes (e.g. changing recovery scheme)

Think of it as the birth certificate + root authority.