Methods (400, 700) and devices (110, 120, 300, 610, 620, 810, 850, 1000, 1100) determine a
hash function to be used before storing and transmitting target identifiers. A
lawful interception, LI, core device (120, 300, 620) then calculates a target identifier hashed value, TIHV, using the
hash function and a hashing key, stores an indication of the
hash function, the hashing key and the TIHV, and transmits the indication, the hashing key and the TIHV to the
network element that is configured to intercept LI data. The
network element applies the hash function with the hashing key to intercepted target identifiers retrieved from intercepted LI data. If one of the intercepted target identifiers hashed values matches a TIHV received from the LI core device, the
network element forwards LI data to the LI core device, which similarly matches and forwards LI data to a law
enforcement monitoring facility.