Derived credential is the best description of an access control method utilizing cryptographic keys derived from a smart card private key that is embedded within mobile devices. A smart card is a device that contains a microchip that stores a private key and a digital certificate that are used for authentication and encryption. A smart card is typically inserted into a reader that is attached to a computer or a terminal, and the user enters a personal identification number (PIN) to unlock the smart card and access the private key and the certificate. A smart card can provide a high level of security and convenience for the user, as it implements a two-factor authentication method that combines something the user has (the smart card) and something the user knows (the PIN).

However, a smart card may not be compatible or convenient for mobile devices, such as smartphones or tablets, that do not have a smart card reader or a USB port. To address this issue, a derived credential is a solution that allows the user to use a mobile device as an alternative to a smart card for authentication and encryption. A derived credential is a cryptographic key and a certificate that are derived from the smart card private key and certificate, and that are stored on the mobile device. A derived credential works as follows:

The user inserts the smart card into a reader that is connected to a computer or a terminal, and enters the PIN to unlock the smart card

The user connects the mobile device to the computer or the terminal via a cable, Bluetooth, or Wi-Fi

The user initiates a request to generate a derived credential on the mobile device

The computer or the terminal verifies the smart card certificate with a trusted CA, and generates a derived credential that contains a cryptographic key and a certificate that are derived from the smart card private key and certificate

The computer or the terminal transfers the derived credential to the mobile device, and stores it in a secure element or a trusted platform module on the device

The user disconnects the mobile device from the computer or the terminal, and removes the smart card from the reader

The user can use the derived credential on the mobile device to authenticate and encrypt the communication with other parties, without requiring the smart card or the PIN

A derived credential can provide a secure and convenient way to use a mobile device as an alternative to a smart card for authentication and encryption, as it implements a two-factor authentication method that combines something the user has (the mobile device) and something the user is (the biometric feature). A derived credential can also comply with the standards and policies for the use of smart cards, such as the Personal Identity Verification (PIV) or the Common Access Card (CAC) programs.

The other options are not the best descriptions of an access control method utilizing cryptographic keys derived from a smart card private key that is embedded within mobile devices, but rather descriptions of other methods or concepts. Temporary security credential is a method that involves issuing a short-lived credential, such as a token or a password, that can be used for a limited time or a specific purpose. Temporary security credential can provide a flexible and dynamic way to grant access to the users or entities, but it does not involve deriving a cryptographic key from a smart card private key. Mobile device credentialing service is a concept that involves providing a service that can issue, manage, or revoke credentials for mobile devices, such as certificates, tokens, or passwords. Mobile device credentialing service can provide a centralized and standardized way to control the access of mobile devices, but it does not involve deriving a cryptographic key from a smart card private key. Digest authentication is a method that involves using a hash function, such as MD5, to generate a digest or a fingerprint of the user’s credentials, such as the username and password, and sending it to the server for verification. Digest authentication can provide a more secure way to authenticate the user than the basic authentication, which sends the credentials in plain text, but it does not involve deriving a cryptographic key from a smart card private key.