openssl rand 16 > ./symmetric.key

openssl genrsa 4096 | openssl pkcs8 -inform PEM -topk8 -v2 aes-128-cbc -nocrypt -out keyfile.pem
openssl pkey -inform PEM -in keyfile.pem -pubout -out keyfile_pkcs.pub

openssl enc  -in firmware.tar -aes-128-cbc -salt -out firmware.enc -pass file:././symmetric.key

openssl pkeyutl -encrypt -pubin -inkey keyfile_pkcs.pub -in symmetric.key -out symmetric.key.enc
openssl pkeyutl -decrypt -inkey keyfile.pem -in symmetric.key.enc -out decrypted_symmetric.key

openssl pkeyutl -sign -inkey keyfile.pem -in symmetric.key -out symmetric.key.enc
openssl pkeyutl -verifyrecover -pubin -inkey keyfile_pkcs.pub -in symmetric.key.enc -out decrypted_symmetric.key