User A has signed a message
msg with signature
sig.How can the third party verify this message in a contract? The verify method contract is like this:
void verify_user_sig(account_name user,string msg,string sig,public_key pubkey);
Because we can know
sig and user's
pubkey ,we can recover the public key in contract.But the problem is how can we know that the
pubkey submitted is the user's public key ?
So the question is:
How to get the account name of a public key in contract?