Digital signature for a file using openssl

To Generate Private Key

openssl genrsa -out privatekey.pem 2048

To Sign

openssl dgst -sha256 -sign privatekey.pem -out data.txt.signature data.txt

To Generate The Public Key

dgst -verify requires the public key

openssl rsa -in privatekey.pem -outform PEM -pubout -out publickey.pem

To Verify

openssl dgst -sha256 -verify publickey.pem -signature data.txt.signature data.txt

• In case of success: prints "Verified OK", return code 0
• In case of failure: prints "Verification Failure", return code 1