A data transmission method and a device are provided. When determining that the first network element and the second network element is disconnected, the first network element stores identification information of the last frame of data and connection status information that are transmitted before the connection is disconnected. When determining a condition for re-communication is meet, the first network element generates a third key based on a first key and a second key, where the first key is a key used to transmit the last frame of data, and the second key includes a key used by the first network element and the second network element to transmit each of j frames of data before the last frame of data. The first network element communicates with the second network element based on the third key, identification information of an i.sup.th frame of data, and the connection status information.

Embodiments described herein provide for a satellite device that can be associated with a user account of a minor aged (e.g., child or adolescent) user that does not have a smartphone that can be used as a companion device to the satellite device. The satellite device can be configured to be used as a primary device, without reliance upon a paired smartphone. Certain information can be synchronized with the satellite device via the association with the family account. During initial configuration, a set of cryptographic keys can be generated to associate the account of the satellite device with the set of accounts in the family. The satellite device can then access calendars, media, or other data that is shared with user accounts within a family of user accounts.

In a key obtaining method and an apparatus, a first core network device obtains a first key, and the first core network device performs derivation based on the first key to obtain a second key and a third key. The second key is for performing security processing on control plane signaling of a terminal device, and the third key is for performing security processing on user plane data of the terminal device. The first core network device sends the second key to a control plane entity of a first access network device, and sends the third key to a user plane entity of the first access network device.

A communication apparatus capable of performing multilink communication conforming to the IEEE802.11 standard series, the communication apparatus includes an establishment unit configured to establish a link with another communication apparatus, and a first sharing unit configured to share, in a case where the establishment unit establishes a first link and a second link between the communication apparatus and the another communication apparatus, a PTK (Pairwise Transient Key) for encryption of unicast communication by 4 Way Handshake processing that is performed with the another communication apparatus in the first link, wherein, in the second link, the PTK is used to encrypt unicast communication in the second link without performing the 4 Way Handshake processing.

Systems and methods are disclosed for managing secure connection between a mobile device and an Internet of things device, such as an electronic lock. In some instances, a mutual authentication process is performed, and public keys are exchanged. Once keys are exchanged, subsequent communication between the devices may be encrypted using a shared key generated using the exchanged keys.

Methods, devices, and systems for pairing with an aspirating smoke detector device are described herein. One device includes a wireless module, a buzzer; and a controller. The wireless module can be configured to receive a connection request from a mobile device, and the controller can be configured to generate a temporary key (TK) having a plurality of digits, cause the buzzer to produce a buzzer signal including a plurality of portions corresponding to the plurality of digits of the TK, receive, via the wireless module, an indication of the TK determined by the mobile device based on the buzzer signal, and communicate with the mobile device to complete a pairing with the mobile device using the TK.

A method of performing a security mode control procedure by a user equipment (UE), and an apparatus therefor are disclosed. The method includes performing, over a 3.sup.rd generation partnership project (3GPP) access, a first authentication procedure and a first key agreement procedure with an access and mobility management function (AMF), wherein a key set identifier (ngKSI) is changed during the first authentication procedure and the first key agreement procedure, receiving, from the AMF over the 3GPP access, a first security mode command message including the ngKSI, and receiving, from the AMF over a non-3GPP access, a second security mode command message including the ngKSI, wherein the UE is registered to the AMF and a same public land mobile network (PLMN) over both the 3GPP access and the non-3GPP access.

A method of performing a security mode control procedure by a user equipment (UE), and an apparatus therefor are disclosed. The method includes performing, over a 3.sup.rd generation partnership project (3GPP) access, a first authentication procedure and a first key agreement procedure with an access and mobility management function (AMF), wherein a key set identifier (ngKSI) is changed during the first authentication procedure and the first key agreement procedure, receiving, from the AMF over the 3GPP access, a first security mode command message including the ngKSI, and receiving, from the AMF over a non-3GPP access, a second security mode command message including the ngKSI, wherein the UE is registered to the AMF and a same public land mobile network (PLMN) over both the 3GPP access and the non-3GPP access.

A communication device may receive a specific signal from a first external device; after the specific signal has been received from the first external device, cause an output unit of the communication device to output specific information obtained by using a public key; after the specific information has been outputted, receive an authentication request in which the public key is used from the first external device; in a case where the authentication request is received from the first external device, send an authentication response to the first external device; after the authentication response has been sent to the first external device, receive connection information from the first external device; and in a case where the connection information is received from the first external device, establish, by using the connection information, a wireless connection between the communication device and a second external device.

A communication device may receive a specific signal from a first external device; after the specific signal has been received from the first external device, cause an output unit of the communication device to output specific information obtained by using a public key; after the specific information has been outputted, receive an authentication request in which the public key is used from the first external device; in a case where the authentication request is received from the first external device, send an authentication response to the first external device; after the authentication response has been sent to the first external device, receive connection information from the first external device; and in a case where the connection information is received from the first external device, establish, by using the connection information, a wireless connection between the communication device and a second external device.