Enable asymmetric keys support

modulename: digsig_asymmetric.ko

configname: CONFIG_INTEGRITY_ASYMMETRIC_KEYS

Linux Kernel Configuration
└─>Security options
└─>Enable asymmetric keys support
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option enables digital signature verification using
asymmetric keys.

source code:
security/integrity/digsig_asymmetric.c