Mint 21.1 Guide

Generating the private key: 

openssl genrsa -out privateKey.pem

Extracting the public key:

openssl rsa -in privateKey.pem -out publicKey.pem -outform PEM -pubout

Encrypting the txt file:

openssl pkeyutl -encrypt -pubin -inkey "publicKey.pem" -in "fileToEncrypt.txt" -out "encryptedFile.txt"

Decrypting the file:

openssl pkeyutl -decrypt -inkey "privateKey.pem" -in "encryptedFile.txt" -out "decryptedFile.txt"

EXTRA:

Signing the file:

openssl pkeyutl -sign -inkey "privateKey.pem" -in "fileToSign.txt" - out "signatureFile.sign"

Veryfing the signature:

openssl pkeyutl .verify -pubin -inkey "publicKey.pem" - in "fileToCheck.txt" -sigfile "signatureFile.sign"