generating master public key from address

Question

I want to know is it possible to generate master public key from an address? if not, what is needed to generate xpub key?

Answer 1

It's not possible. An address is created though a hash160 (RIPEMD160) which is a one-way function.

Creating a xpub key (bip32 extended public key) requires the according pubkey and the chaincode. Alternatively you can calculate an xpub from an xpriv (extended private key).