4.2.42 EF_Hiddenkey (Key for hidden phone book entries)

31.1023GPPCharacteristics of the Universal Subscriber Identity Module (USIM) applicationRelease 17TS

This EF contains the hidden key that has to be verified by the ME in order to display the phone book entries that are marked as hidden. The hidden key can consist of 4 to 8 digits.

Identifier: ‘6FC3’		Structure: transparent			Optional
File size: 4 bytes			Update activity: low
Access Conditions: READ PIN UPDATE PIN DEACTIVATE ADM ACTIVATE ADM
Bytes	Description			M/O		Length
1 to 4	Hidden Key			M		4 bytes

‑ Hidden Key.

Coding:

– the hidden key is coded on 4 bytes using BCD coding. The minimum number of digits is 4. Unused digits are padded with ‘F’.

NOTE 1: Digits are not swapped, i.e. for instance the key "1234" is coded as ’12 34 FF FF’.

NOTE 2: The phone book entries marked as hidden are not scrambled by means of the hidden key. They are stored in plain text in the phone book.