Access stratum security for efficient packet processing
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.
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;
communicating a first set of messages with the first cell node using the first key for enciphering or deciphering the first set of messages;
deriving a second key based on the first key and a counter;
using the second key for enciphering or deciphering a second set of messages to or from the first cell node or a second cell node;
receiving a third set of messages, enciphered using the second key, indicating a third key from the second cell node;
using the third key for enciphering or deciphering a fourth set of messages to or from the second cell node;
obtaining another indication of the key area ID from the second cell node; and
communicating a fifth set of messages with the second cell node using the second key for enciphering or deciphering portions of each of the fifth set of messages.
2. The method of claim 1 , wherein the fifth set of messages comprises radio resource control (RRC) connection request messages.
3. The method of claim 1 , further comprising receiving an indication of a key change and the counter from the first cell node or the second cell node.
4. 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;
communicating a first set of messages with the first cell node using the first key for enciphering or deciphering the first set of messages;
deriving a second key based on the first key and a counter;
using the second key for enciphering or deciphering a second set of messages to or from the first cell node or a second cell node;
receiving a third set of messages, enciphered using the second key, indicating a third key from the second cell node;
using the third key for enciphering or deciphering a fourth set of messages to or from the second cell node;
obtaining another indication of the key area ID from the second cell node; and
communicating a fifth set of messages with the second cell node using the first key for enciphering or deciphering the fifth set of messages.
5. 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;
communicating a first set of messages with the first cell node using the first key for enciphering or deciphering the first set of messages;
deriving a second key based on the first key and a counter;
using the second key for enciphering or deciphering a second set of messages to or from the first cell node or a second cell node;
receiving a third set of messages, enciphered using the second key, indicating a third key from the second cell node;
using the third key for enciphering or deciphering a fourth set of messages to or from the second cell node;
receiving a fifth set of messages, enciphered using the first key, indicating the second key from the first cell node; and
using the second key for enciphering or deciphering a sixth set of messages to or from the first cell node.