# US 12,003,957 B2 · Distributed network cellular identity management

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- Number: US 12,003,957 B2
- Document ID: US12003957B2
- Status: Granted
- Kind: B2
- Application number: 17/281,207
- Filed: 2019-09-30
- Published: 2021-12-23
- Granted: 2024-06-04
- Earliest claimed: 2018-10-04
- Assignees: Google Inc.
- Applicants: Google LLC
- Inventors: Erik Richard Stauffer; Jibing Wang
- Web page: https://patentgrep.com/patent/US12003957B2

## CPC

- H04L 9/50: {using hash chains, e.g. blockchains or hash trees}
- H04W 12/041: Key generation or derivation
- H04L 9/0618: {Block ciphers, i.e. encrypting groups of characters of a plain text message using fixed encryption transformation}
- H04L 9/0825: {using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates}
- H04L 9/3239: {involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD}
- H04L 9/3271: {using challenge-response}
- H04L 63/0442: {wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption (cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30)}
- H04L 63/0869: {for achieving mutual authentication (cryptographic mechanisms or cryptographic arrangements for mutual authentication H04L9/3273)}
- H04W 12/06: Authentication
- H04L 63/0428: {wherein the data content is protected, e.g. by encrypting or encapsulating the payload}
- H04L 2209/80: Wireless
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

This document describes techniques and apparatuses for distributed network cellular identity management. In particular, a distributed-network cellular-identity-management (DNCIM) server includes a lookup table that stores and relates together a user-equipment (UE) public key associated with a UE private key, a core-network (CN) public key associated with a CN private key, and a subscriber identity. Using the DNCIM server, the UE and an authentication server respectively generate two different (e.g., asymmetric) cipher keys based on the UE private key and the CN public key, and the UE public key and the CN private key. The UE and the authentication server can also authenticate one another by referencing information in the lookup table of the DNCIM server. Using these cipher keys, the UE and the authentication server can establish secure communications with each other.

## Claims

### Claim 1

A method performed by an authentication server,
the method comprising:
receiving a first subscriber identity from a user equipment;
storing a core-network public key, a core-network private key associated with the core-network public key, and an expected payload;
in response to sending the first subscriber identity to a distributed-network cellular-identity management, DNCIM, server, receiving a user-equipment public key associated with the user equipment;
generating a first cipher key based on both the user-equipment public key and the core-network private key;
in response to sending, to the user equipment, a message encrypted using the user-equipment public key and including the core-network public key, receiving a first encrypted message from the user equipment, the first encrypted message including a first payload encrypted with a second cipher key that is based on a user-equipment private key and the core-network public key;
decrypting the first encrypted message using the first cipher key to obtain the first payload; and
upon verifying the first cipher key and the second cipher key based on a determination that the first payload of the first encrypted message is equal to the expected payload, authenticating the user equipment based on communicating with the DNCIM server.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
responsive to the authenticating the user equipment, sending, to the user equipment, a second encrypted message including a second payload that is encrypted with the first cipher key, the second encrypted message being decryptable using the second cipher key.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
receiving a third encrypted message from the user equipment, the third encrypted message including a third payload encrypted with the second cipher key; and
responsive to authenticating the user equipment, decrypting the third encrypted message using the first cipher key to determine the third payload.

### Claim 4 (depends on 1)

The method of claim 1, wherein:
the message encrypted using the user-equipment public key further includes a nonce and the expected payload comprises the nonce; or
the message encrypted using the user-equipment public key further includes a predetermined number and the expected payload comprises the predetermined number.

### Claim 5 (depends on 1)

The method of claim 1, wherein the authenticating the user equipment comprises:
sending the user-equipment public key to DNCIM server;
receiving a second subscriber identity from the DNCIM server; and
determining the user equipment is authentic based on matching the first subscriber identity with the second subscriber identity.

### Claim 6

An authentication server configured to:
receive a first subscriber identity from a user equipment;
store a core-network public key, a core-network private key associated with the core-network public key, and an expected payload;
in response to sending the first subscriber identity to a distributed network cellular identity management, DNCIM, server, receive a user-equipment public key associated with the user equipment;
generate a first cipher key based on both the user-equipment public key and the core-network private key;
in response to sending, to the user equipment, a message encrypted using the user-equipment public key and including the core-network public key, receive a first encrypted message from the user equipment, the first encrypted message including a first payload encrypted with a second cipher key that is based on a user-equipment private key and the core-network public key;
decrypt the first encrypted message using the first cipher key to obtain the first payload;
upon verifying the first cipher key and the second cipher key based on a determination that the first payload of the first encrypted message is equal to the expected payload, and authenticate the user equipment based on communicating with the DNCIM server.

### Claim 7 (depends on 6)

The authentication server of claim 6, further configured to:
send a second encrypted message to the user equipment responsive to authenticating the user equipment, the second encrypted message including a second payload that is encrypted with the first cipher key and is decryptable using the second cipher key.

### Claim 8 (depends on 6)

The authentication server of claim 6, further configured to:
receive a third encrypted message from the user equipment, the third encrypted message including a third payload encrypted with the second cipher key; and
responsive to authenticating the user equipment, decrypt the third encrypted message using the first cipher key to determine the third payload.

### Claim 9 (depends on 6)

The authentication server of claim 6, further configured to:
the message encrypted using the user-equipment public key further includes a nonce and the expected payload comprises the nonce; or
the message encrypted using the user-equipment public key further payload includes a predetermined number and the expected payload comprises the predetermined number.