The iButton M card reader is designed for reading and writing on Mifare® 13.56 MHz cards and its installation in tight spaces. The communication between the reader and the ACU is protected by 128bit AES encryption. This encryption prevents the monitoring of communication between the two. The iButton M reader allows the use of encrypted Mifare® sectors to store the card's serial number, avoiding the use of the card's CSN as it is unprotected and insecure. Thanks to the ability to read / write, the iButton M reader also allows the use of DOC SYNC™ technology for the integration of autonomous devices.