SAM module in Payment transactions & cryptogram key storing

[dizgah]

Hi every one,
As you know because of low security factors,General MCU's are not appropriate choice for storing Transaction or cryptograms keys.Therefor embedded systems developers used SAM modules for secure storing these Keys .SAM stay on among MCU & Card reader,then being responsible for all key transceiving .

As you can see these are only titles of its function ,but I'm looking for practical approaches and detail of using SAM module to en-securing a payment methods such as protocols, HW/SW layers & ...