How to validate kexts signatures from the command line?
Here's the script which will output not singed kexts inside this directory:

#!/bin/bash                                                                                                                                                                                                        

cd /System/Library/Extensions

find *.kext -prune -type d | while read d; do
    codesign -d "$d" 2&gt;/dev/null
    rc=$?
    if [[ $rc != 0 ]] ; then
        echo "$d" is not signed.
    fi
done