# US 2020/0351256 A1 · Access stratum security for efficient packet processing

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- Number: US 2020/0351256 A1
- Document ID: US20200351256A1
- Status: Published application
- Kind: A1
- Application number: 16/936,347
- Filed: 2020-07-22
- Published: 2020-11-05
- Earliest claimed: 2016-09-23
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Soo Bum LEE; Keiichi KUBOTA; Adrian Edward ESCOTT; Gavin Bernard HORN; Anand PALANIGOUNDER
- Web page: https://patentgrep.com/patent/US20200351256A1

## CPC

- H04W 12/04: Key management, e.g. using generic bootstrapping architecture [GBA]
- H04L 63/0428: {wherein the data content is protected, e.g. by encrypting or encapsulating the payload}
- H04L 63/068: {using time-dependent keys, e.g. periodically changing keys (cryptographic mechanisms or cryptographic arrangements for controlling usage of secret information H04L9/088)}
- H04W 12/03: Protecting confidentiality, e.g. by encryption
- H04W 12/041: Key generation or derivation
- H04W 12/043: using a trusted network node as an anchor
- H04W 12/062: Pre-authentication
- H04L 9/08: Key distribution {or management, e.g. generation, sharing or updating, of cryptographic keys or passwords (network architectures or network communication protocols for supporting key management in a packet data network H04L63/06)}
- H04W 12/06: Authentication
- H04W 24/02: Arrangements for optimising operational condition
- H04W 36/0038: {of security context information}
- H04W 48/16: Discovering, processing access restriction or access information
- H04W 48/18: Selecting a network or a communication service
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Certain aspects of the present disclosure provide techniques for managing security keys for enciphering and deciphering packets transmitted in a wireless communications system. According to certain aspects, a method of wireless communication by a user equipment (UE) is provided. The method generally includes obtaining an indication of a key area identifier (ID) of a first cell node, wherein the key area ID identifies a set of cell nodes that are associated with a network node that uses a first key for enciphering or deciphering messages and communicating a first set of messages with the first cell node using the first key for enciphering or deciphering the first set of messages.

## Claims

### Claim 1

A method for wireless communications by a user equipment (UE), comprising:
obtaining an indication of a key area identifier (ID) of a first cell node, wherein the key area ID identifies a set of cell nodes that are associated with a network node that uses a first key for enciphering or deciphering messages; and
communicating a first set of messages with the first cell node using the first key for enciphering or deciphering the first set of messages.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
obtaining another indication of the key area ID from a second cell node; and
communicating a second set of messages with the second cell node using a second key, related to the first key, for enciphering or deciphering portions of each of the second set of messages.

### Claim 3 (depends on 2)

The method of claim 2, wherein the second set of messages comprise radio resource control (RRC) connection request messages.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
obtaining another indication of the key area ID from a second cell node; and
communicating a second set of messages with the second cell node using the first key for enciphering or deciphering the second set of messages.

### Claim 5 (depends on 2)

The method of claim 2, further comprising:
receiving a third set of messages, enciphered using the second key, indicating a third key from the second cell node; and
using the third key for enciphering or deciphering a fourth set of messages to or from the second cell node.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
receiving a second set of messages, enciphered using the first key, indicating a second key from the first cell node;
using the second key for enciphering or deciphering a third set of messages to or from the first cell node.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
receiving an indication of a key change and a corresponding counter from the first cell node or a second cell node;
deriving a second key based on the first key and the corresponding counter; and
using the second key for enciphering or deciphering second messages to or from the first cell node or the second cell node.

### Claim 8

A method for wireless communications by a user equipment (UE), comprising:
sending a radio resource control (RRC) connection reestablishment request message to a first cell node;
obtaining an indication of a first key area identifier (ID) of the first cell node, wherein the first key area ID identifies a set of cell nodes that are associated with a network node that uses a key for enciphering or deciphering messages;
obtaining the key associated with the first key area ID;
receiving an RRC connection reestablishment message from the first cell node or another network node; and
authenticating the RRC connection reestablishment message with the key associated with the first key area ID.

### Claim 9 (depends on 8)

The method of claim 8, wherein the indication of the first key area ID comprises a list of IDs associated with the first key area ID and is obtained via RRC signaling.

### Claim 10 (depends on 9)

The method of claim 9, wherein the list of IDs associated with the first key area ID comprises a list of IDs associated with the set of cell nodes.

### Claim 11 (depends on 10)

The method of claim 10, wherein the list of IDs associated with the set of cell nodes comprises a list of cell global IDs (CGIs) associated with one or more cell nodes in the set of cell nodes.

### Claim 12 (depends on 8)

The method of claim 8, wherein:
the set of cell nodes comprises a second cell node;
the RRC connection reestablishment message is received from the other network node; and
the other network node comprises the second cell node.

### Claim 13

A method for wireless communications performed by a cell node, comprising:
providing an indication of a key area identifier (ID) of the cell node, wherein the key area ID identifies a set of cell nodes that are associated with a network node that uses a first key for enciphering or deciphering messages; and
communicating a first set of messages with a user equipment (UE) using the first key for enciphering or deciphering the first set of messages.

### Claim 14 (depends on 13)

The method of claim 13, further comprising:
providing an indication to the UE of a key change and a corresponding counter;
deriving a second key based on the first key and the corresponding counter; and
communicating a second set of messages with the UE using the second key for enciphering or deciphering the second set of messages.

### Claim 15 (depends on 14)

The method of claim 14, wherein the second set of messages comprise radio resource control (RRC) connection request messages.

### Claim 16

A method for wireless communications by a network node, comprising:
receiving a radio resource control (RRC) connection reestablishment request message from a user equipment (UE) via a cell node;
obtaining a key associated with a first key area identifier (ID) associated with the cell node, wherein the first key area ID identifies a set of cell nodes that are associated with the network node that uses a first key for enciphering or deciphering messages; and
authenticating the RRC connection reestablishment request message with the key.

### Claim 17 (depends on 16)

The method of claim 16, further comprising:
transmitting an indication of the first key area ID to the UE.

### Claim 18 (depends on 17)

The method of claim 17, wherein transmitting the indication comprises transmitting a list of IDs associated with the first key area ID via an RRC signal.

### Claim 19 (depends on 18)

The method of claim 18, wherein the list of IDs associated with the first key area ID comprises a list of IDs associated with the set of cell nodes.

### Claim 20 (depends on 19)

The method of claim 19, wherein the list of IDs associated with the set of cell nodes comprises a list of cell global IDs (CGIs) associated with one or more cell nodes in the set of cell nodes.