kernelconfig_penguin
CONFIG_KEXEC_IMAGE_VERIFY_SIG is not available for the default architecture x86.
Result is shown for architecture arm64

Enable Image signature verification support

configname: CONFIG_KEXEC_IMAGE_VERIFY_SIG

Linux Kernel Configuration
└─> Kernel Features
└─> Enable Image signature verification support

In linux kernel since version 5 (release Date: 2019-03-03)  

Enable Image signature verification support.