Secure re-use of SIM security parameters
AssigneeEvolving Systems, Inc.
InventorDavid Thorn
Life of this patent
Estimating the term…
Abstract
Various arrangements for using a SIM card across multiple wireless networks are presented. A DKi value may be stored by the SIM card. The SIM card may calculated a FKi value using the DKi value and a stored BKi value. The SIM card can attach to a guest wireless network. A challenge may be received by the SIM card from the guest wireless network. The SIM card may calculate an answer to the challenge using the FKi value. The answer may be transmitted to the wireless network. In response to the answer being correct, the wireless device having the SIM card installed is successfully authenticated to use the wireless network.
Claims17
A method for using a subscriber identification module (SIM) card across multiple wireless networks, the method comprising:
- calculating, by a SIM card owner system, a DKi (delta Ki) value, wherein the DKi value is editable and calculated by subtracting a Bki value from a random number;
- providing, by the SIM card owner system, via a wireless network, the DKi value to the SIM card;
- storing, by the SIM card, the DKi value, wherein the SIM card has an immutable BKi (base Ki) value that is permanently stored;
- calculating, by the SIM card, a FKi (full Ki) value using the DKi value and the BKi value;
- attaching, by the SIM card, to a guest wireless network, wherein the SIM card is installed within a wireless device;
- receiving, by the SIM card, from the guest wireless network, a challenge;
- calculating, by the SIM card, an answer to the challenge using the FKi value;
- and
- transmitting the answer to the wireless network, wherein in response to the answer being correct, the wireless device having the SIM card installed is successfully authenticated to use the wireless network.
A system that uses a subscriber identification module (SIM) card, the system comprising:
- a SIM card, configured to:
- store an international mobile subscriber identity (IMSI);
- store a BKi (base Ki) value that is immutable, the BKi value being permanently stored by the SIM card;
- store a DKi (delta Ki) value that is editable, wherein:
- the DKi value is calculated by subtracting the Bki value from a random number;
- and
- the DKi value is provided by a SIM card owner system to the SIM card via a wireless network;
- calculate a FKi (full Ki) value using the DKi value and the BKi value;
- calculate a response to a challenge using the calculated FKI;
- and
- output the response to the challenge and an IMSI for transmission to the wireless network.
Dependencies are inferred from the claim text.