Apple is researching ways to allow multiple users to benefit from Touch ID, or similar biometric systems, while keeping the protection of the current secure enclave. Apple's T2 security processor is based around a secure enclave which stores biometric data about a user. Whether that user is unlocking their Mac, or making a purchase, the secure enclave is asked to confirm that they are who they say they are. Without divulging any of the stored data, the T2 processor can confirm or deny a request. So the Mac or the retailer has the certainty they need to proceed, without the user's privacy being compromised.