Shortly after the iPhone X was unveiled, United States Senator Al Franken, who is a member of the Senate Judiciary Committee on Privacy, Technology, and the Law, sent a letter to Apple CEO Tim Cook to ask several questions about the security and the privacy of Face ID.

Franken asked Apple to address his questions by October 13, 2017, which Apple did through a letter sent by Cynthia Hogan, the company's Vice President for Public Policy in the Americas.

In the letter, Hogan highlights its recent Face ID security paper and Face ID support document , which outline how Apple protects customer privacy and keeps customer data secure.

She also addresses several of Franken's questions, reiterating much of the information that's in the two documents and that's been previously published about Face ID. One of Franken's questions, for example, concerned how Face ID was trained, with Apple's response below:

The accessibility of the product to people of diverse races and ethnicities was very important to us. Face ID uses facial matching neural networks that we developed using over a billion images, including IR and depth images collected in studies conducted with the participants' informed consent. We worked with participants from around the world to include a representative group of people accounting for gender, age, ethnicity, and other factors. We augmented studies as needed to provide a high degree of accuracy for a diverse range of users. In addition, a neural network that is trained to spot and resist spoofing defends against attempts to unlock your phone with photos or masks.

Hogan ends the letter with an offer to provide Senator Franken with briefings on Apple products should additional information be required.

Following his receipt of the letter, Franken today issued a statement where he said he appreciates Apple's willingness to provide information on Face ID.

All the time, we learn about and actually experience new technologies and innovations that just a few years back were difficult to even imagine. While these developments are often great for families, businesses, and our economy, they also raise important questions about how we protect what I believe are among the most pressing issues facing consumers: privacy and security. I appreciate Apple's willingness to engage with my office on these issues, and I'm glad to see the steps that the company has taken to address consumer privacy and security concerns. I plan to follow up with Apple to find out more about how it plans to protect the data of customers who decide to use the latest generation of iPhone's facial recognition technology.

In addition to offering up a Face ID white paper and detailed support document, Apple has also provided information on Face ID through a series of interviews software engineering chief Craig Federighi did with various media sites.

Face ID will be available to consumers starting on November 3, the official launch date for the iPhone X. Apple plans to begin accepting pre-orders for the iPhone X on October 27.