Embodiments relate generally to electrical and electronic hardware, computer software, wired and wireless network communications, and wearable computing devices for facilitating health and wellness-related information, and more particularly, to an apparatus or method for using a wearable device (or carried device) having sensors to identify a wearer and/or generate a biometric identifier for security and authentication purposes (e.g., using the generated biometric identifier similar to a passcode). In some embodiments, a biometric validator is included to validate the accuracy of the biometric identifier to authenticate the identity of the user. The biometric validator can determine conditions in which the biometric identifier is invalid (e.g., when a wearable device is no longer worn by a user).