default or selected kernelversion does not have config value CONFIG_NCPFS_PACKET_SIGNING.
Result is shown for kernelversion 6.7-rc3

Packet signatures


Linux Kernel Configuration
└─>File systems
└─>Network File Systems
└─>Packet signatures
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
NCP allows packets to be signed for stronger security. If you want
security, say Y. Normal users can leave it off. To be able to use
packet signing you must use ncpfs > 2.0.12.