Securing shared systems

With increasing reliance on new and interactive technologies, a challenge producers face is the requirement of a secure system to control users of their cooperative designs or applications to reap economic benefit. An authentication code is the series of letters and numbers, often disclosed after purchasing a product or service and that allows access for that user. This paper provides insight into the generation and verification of existing authentication codes and proposes a new scheme, which uses cryptography to embed mathematical structure within the codes to better protect cooperative applications. The proposed method uses a changing key based on a secret key and a random number, and symmetrical block cipher