In brief: Amazon is offering $10 in credit to everyone that scans and saves their palm prints into their Amazon accounts for authentication purposes within their stores, and that's something that has raised eyebrows among US senators. Yesterday, a group of senators sent a letter to Amazon explaining their concerns and listing some questions they would like to be answered.

With Amazon One, the company is hoping to make payment for your groceries simpler and faster by scanning your palm. For now, you can use it in a few Amazon Go, Amazon Books, and Amazon 4-star stores, but if it becomes more mainstream, it will expand to more locations.

To promote the new technology, Amazon is giving away $10 in credit for anyone that links their palm to their Amazon account. This can be done in participating physical Amazon stores. Once the process is complete, users will receive an email with the $10 credit.

Following these events, US Senators Amy Klobuchar, Bill Cassidy and Jon Ossoff wrote a letter to Andy Jassy, CEO of Amazon, explaining their concerns over the system's security, Amazon's $10 credit promotion, and how the company will use this data. The letter is also accompanied by some questions that the US senators would like to see answered by August 26, 2021.

"Our concerns about user privacy are heightened by evidence that Amazon shared voice data with third-party contractors and allegations that Amazon has violated biometric privacy laws," wrote the Senators in the letter. "We are also concerned that Amazon may use data from Amazon One, including data from third-party customers that may purchase and use Amazon One devices, to further cement its competitive power and suppress competition across various markets."

Unlike companies such as Apple and Samsung, Amazon wouldn't be storing the biometrics data in the user's device. Instead, the data is uploaded to Amazon's cloud so buyers can use it in different stores. By storing it on the cloud, there's the risk that this information may be leaked or stolen through cyber attacks or exploiting a vulnerability in Amazon's systems.

This isn't the first time Amazon is questioned by the US Senate to hand out details about their biometrics systems. In 2018, ACLU tested Amazon's 'Rekognition' facial recognition tech, identifying 28 lawmakers as criminals. Following these results, both the Senate and the House of the Representatives sent a letter to Amazon asking for details about the technology.