# simple file encryption
# encrypted file size < key size

openssl genrsa -out private.pem 1024
openssl rsa -in private.pem -out public.pem -outform PEM -pubout
openssl rsautl -encrypt -inkey public.pem -pubin -in file.txt -out file.ssl
openssl rsautl -decrypt -inkey private.pem -in file.ssl -out decrypted.txt

# simple file signature 
openssl rsautl -sign -in file -inkey key.pem -out sig

# verify signature
openssl rsautl -verify -in sig -inkey key.pem