In order to ensure that a Subscription Concealed Identifier, SUCI, is calculated in the Universal Subscriber Identity Module, USIM, part of a User Equipment, UE, when intended, when a SUCI-Calculation-Indicator is set to a value indicating that the SUCI should be calculated in the USIM, a network node sets proprietary information, which is not known to a Mobile Equipment, ME, part of the UE, as required for calculation of the SUCI. The USIM facilitates calculation of the SUCI in the ME part of the UE only when the SUCI-Calculation-Indicator is set to a value indicating that the SUCI should be calculated in the ME. When the SUCI-Calculation-Indicator is set to a value indicating that the SUCI should be calculated in the USIM, the ME part deletes any locally stored information required for calculation of the SUCI.