> For the complete documentation index, see [llms.txt](https://developer.magtek.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.magtek.com/hardware/card-readers/mms-dyna-devices/dynaflex-ii-go/documents/developers-manuals/programmers-manual-commands/security/about-encryption-and-decryption.md).

# About Encryption and Decryption

Some data exchanged between the device and the host is encrypted. This includes parts of the EMV ARQC Type and the EMV Batch Data Type. To decrypt this data, the host must first determine what key to use, then decrypt the data. The following sections explain each of those steps in detail.


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