Check public keys on contract level

Question

Is it meanwhile possible to check the public key of an account name on contract level? (Not with Cleos)

Example: The contract contains some public keys (not the account names). If a user performs a function in the contract, the contract should check if the user name belongs to one of the keys.

Answer 1

The only way is by using recover_key(), assert_recover_key() or assert_recover_key2() while passing an additional signature and digest to the action, as described here:

recover_key in contract