Which of the following authenticator methods is NOT device bound and hardware protected?

The correct answer is Google Authenticator because it operates as a software-based application that generates time-based one-time passwords (TOTPs) on a user's device. Unlike device-bound authentication methods, where credentials are tied to a specific device and often protected by hardware features like Secure Enclaves or Trusted Execution Environments, Google Authenticator does not require any hardware-specific protections. This means that, while the app provides a method of two-factor authentication (2FA), it does not inherently leverage hardware security features that would bind it to the device at a deeper level.

In contrast, options such as Okta Verify leverage device-bound security because they utilize secure elements within the hardware to store cryptographic keys or perform secure operations, thus providing a stronger layer of protection. The same applies to Hardware Security Modules, which are specifically designed to manage and protect cryptographic keys using hardware-based measures to prevent unauthorized access. The "Phone" option can refer to both device-bound and non-device-bound methods, but typically it is contextualized with the secure storage of credentials, unlike Google Authenticator.