To prevent gaming of a reputation system, a security token is generated for a security module using metadata about the client observed during the registration of the security module. The registration server selects metadata for use in generating the security token. The generated security token is provided to identify the client in later transactions. A security server may conduct a transaction with the client and observe metadata about the client during the transaction. The security server also extracts metadata from the security token. The security server correlates the observed metadata during the transaction with the extracted metadata from the security token. Based on the result of the correlation, a security policy is applied. As a result, the metadata in the security token enables stateless verification of the client.