encrypt file or string using SSH public key.md

Convert the public key into specify key format (PKCS8)

ssh-keygen -f ~/.ssh/id_rsa.pub -e -m PKCS8 > ~/.ssh/id_rsa.pem

Using the public PKCS8 file to encrypt a string

echo "sometext" | openssl rsautl -encrypt -pubin -inkey ~/.ssh/id_rsa.pem > ~/encrypted-file.txt

OR file

openssl rsautl -encrypt -inkey ~/.ssh/id_rsa.pem -pubin -in ~/secure-message-file.txt -out ~/encrypted-file.txt

To decrypt, you'll need the private key

openssl rsautl -decrypt -inkey ~/.ssh/id_rsa -in ~/encrypted-file.txt -out ~/decrypted-file.txt