使用openssl实现ECDSA签名和验证。

I am trying to create C program were I can choose from a menu which options I want from Signing a message and Verify a message. I have the code that signs the message and verifies at the same time. What I would like was to be able to parse a message and sign it and this to output the certificate for example. Next when I choose verify I would insert the same message and the certificate, so I could actually verify or not the message.I am trying to create C program were I can choo