The NYC subway’s new tap-to-pay system has a hidden cost – rider data (theverge.com)

"The MTA maintains that it retains all information securely with triple DES encryption and that such data is never decrypted. "

https://csrc.nist.gov/News/2017/Update-to-Current-Use-and-De...

As of 2019 NIST has recommended getting off of 3DES