====== Multi-factor Authentication Options ======

==== Personal Code (PF) ====

To proof his/her identity ADUCID provides a feature called **personal code**
  * Personal Code something only user knows
  * ADUCID uses a picture sequence or number sequence
  * User has only one PF for all his services and devices


==== Comfort factor (CF) ====
As soon as Personal Code is created user can add a comfort factor. 
When service provider allows, 

  * CF can be used instead of PF
  * PF can always be used instead CF

Possible types of the Comfort factor:
| NFC | On Android phone a user can use a NFC tag. |
| Apple Touch ID | On iOS devices with fingerprint sensor (iPhone 5S or better) user can activate fingerprint factor as addition to his / her secret. |
| Apple Face ID | On iPhone X user can activate face recognition factor as addition to his / her secret. |
| Fingerprint | For phones with native Android fingerprint support (not for proprietary implementations). |
| Bluetooth | User can user some BT device like sport tester - something she/he has. When BT device is visible, CF authentication is automatically resolved. |

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