Enhanced subscriber authentication protocol

• US 20020018569A1
• Filed: 06/04/2001
• Published: 02/14/2002
• Est. Priority Date: 12/04/1998
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Certicom Corporation (Blackberry Limited)
• Inventors: Blake-Wilson, Simon, Panjwani, Prakash
• Granted Patent: US 7,123,721 B2
• Time in Patent Office: Days
• US Class Current: 380/247
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04L 63/0869 for achieving mutual authentication cryptographic mechanisms or cryptographic arrangements for mutual authentication H04L9/3273
• CPC Class Codes: H04W 12/041 Key generation or derivation
• CPC Class Codes: H04W 12/0471 Key exchange
• CPC Class Codes: H04W 12/069 using certificates or pre-shared keys

Abstract

The present invention provides a method of authenticating a pair of correspondents in a communication system, such as in a mobile phone network by utilizing a blend of public-key cryptography and symmetric cryptography. Each session between the mobile phone and the network consists of public-key based mutual authentication and key exchange followed by symmetric-key secure data exchange.

Claims

1. A method of authenticating a pair of correspondents in a communication system, said method comprising the steps of:

Exchanging cryptographic keys between said corespondents, said exchange being based on a public key mutual authentication scheme; and

using said keys for encrypting data in a symmetric-key data exchange.

2. A method as defined in claim 1, a first of said correspondents being a mobile station and a second of said correspondents being a base station.

3. A method as defined in claim 2, said mutual authentication including the steps of:

said base station transmitting a short term public key along with an identifier to said mobile station;

said mobile station combining its private key with said base station session public key and generating a pair of shared secret keys therefrom wherein a first of said keys is used for mutual authentication between said mobile station and said base station and a second of said keys is used for establishing a secret session key.

4. A method as defined in claim 3, including the steps of:

said mobile station computing an authentication string using the first of said keys and transmitting same to said base station as a registration request.

5. A method as defined in claim 3, including the steps of:

said base station retrieving said mobile station public key and using said mobile station public key and its short-lived private key for computing a second pair of shared secret keys;

comparing said first keys; and

computing a pair of session keys for transmission to the mobile station.

6. A method for mutual authentication between a base station and a mobile station comprising the steps of:

the mobile station authenticating itself to the base station using its private key;

the base station authenticating itself to the mobile station using the mobile station'"'"'s public key obtained by said base station from a trusted correspondent.