1. A method comprising: generating a set of multiple verification algorithms; generating multiple versions of an authentication code associated with a protected resource, wherein each of the multiple versions of the authentication code satisfies all of the multiple verification algorithms; providing a first version of the authentication code from the multiple versions of the authentication code to a recipient, wherein the first version of the authentication code includes a first verification algorithm from the set of multiple verification algorithms; and providing a second version of the authentication code from the multiple versions of the authentication code to the recipient, wherein the second version of the authentication code includes (i) the first verification algorithm from the set of multiple verification algorithms and (ii) a second verification algorithm from the set of multiple verification algorithms; wherein said generating and said providing are carried out by a computing device.