lastDeviceRecoveryChallenge

The challenge for recovering target with its user's last-device recovery key: the target's outstanding challenge while it is valid for the current registration, else a new random one valid for dev.kreienbuehl.ksecuremessage.protocol.LastDeviceRecovery.CHALLENGE_LIFETIME. Public. Throws LastDeviceRecoveryException.TargetNotRegistered or LastDeviceRecoveryException.NotConfigured.