Verbesserte Sicherheit in zellulären Telefonen

摘要

In a system for delivering a security code to a cellular telephone (3) the cellular telephone holds a key X. The cellular telephone requests that an Authorization Center, AC, (6) assign a security code to the cellular telephone. The AC selects a security code, and encrypts it, such that key X is effective to de-crypt the code, yet the AC does not know key X.