secure:
#imgheaderinsert will create "xxx-sign.bin"
imgheaderinsert xxx.bin 0 0
#old#sprd_sign xxx-sign.bin config pkcs15
sprd_sign xxx-sign.bin config pss
insecure:
imgheaderinsert xxx.bin 1 0
based on VBMetaKeysExtractor fully rewritten according to Google avb
Usage: generate_sign_script_for_vbmeta vbmeta-sign.img