I am a newbie to SSL

1. With openssl versions release so far, is it possible to create public
key certificate with signature algorithm : sha2withRSAEncryption?

2. Message Digest Algorithm I will use is SHA-2, therefore, is it
necessary to change signature algorithm from sha1withRSAEncryption to
sha2withRSAEncryption, MAC --> HMAC/SHA2 and so on…which means parts that
related to SHA…will all use SHA-2?