Abstract: Techniques are disclosed relating to secure message exchanges. In some embodiments, a first computing device generates an account key associated with a user account shared by a plurality of computing devices. The first computing device signs a public key of the first computing device with the generated account key to produce a digital signature and sends the public key and the digital signature to a first server system for distributing the public key to a second computing device attempting to send an encrypted message to the first computing device. The first computing device sends the account key to an external storage external usable by others of the plurality of computing devices to obtain the account key and use the account key to sign public keys of the other computing devices. The first computing device receives, from the second computing device, the encrypted message encrypted using the public key.

Abstract: A device implementing a system for device-relationship based communication includes at least one processor configured to establish, by a first device associated with a first user, a secure communication channel with a second device associated with a second user via a direct wireless connection. The at least one processor is configured to transmit, over the secure communication channel, first device-identifying information to the second device, and receive, over the secure communication channel, second device-identifying information from the second device. The at least one processor is configured to establish a particular type of relationship with the second device, store the second device-identifying information in association with an indication of the particular type of relationship established with the second device, and transmit, to the second device and over the secure communication channel, the indication of the particular type of relationship established with the second device.

Abstract: A device implementing a system for device-relationship based communication includes at least one processor configured to establish, by a first device associated with a first user, a secure communication channel with a second device associated with a second user via a direct wireless connection. The at least one processor is configured to transmit, over the secure communication channel, first device-identifying information to the second device, and receive, over the secure communication channel, second device-identifying information from the second device. The at least one processor is configured to establish a particular type of relationship with the second device, store the second device-identifying information in association with an indication of the particular type of relationship established with the second device, and transmit, to the second device and over the secure communication channel, the indication of the particular type of relationship established with the second device.

Abstract: Implementations of the subject technology provide for performing, by a device, a request for obtaining information related to a phone authentication certificate (PAC) that was generated for the device, the PAC authenticating that a particular phone number is associated with the device, the request including packets of data. The subject technology receives the information related to the PAC, the information including an indication that the PAC was generated for the device. The subject technology sends, from the device, a request for validating the PAC to a remote server based at least in part on the information related to the PAC. Further, the subject technology receives a confirmation of validating the PAC from the remote server based at least in part on the information related to the PAC.

Abstract: Techniques are disclosed relating to multiway communications. In some embodiments, a first electronic device initiates a multiway call between a plurality of electronic devices and exchanges a first secret with a first set of electronic devices participating during a first portion of the multiway call, the first secret being used to encrypt traffic between the first set of electronic devices. The first electronic device receives an indication that first set of participating electronic devices has changed and, in response to the indication, exchanges a second secret with a second set of electronic devices participating during a second portion of the multiway call, the second secret being used to encrypt traffic between the second set of participating electronic devices. In some embodiments, the indication identifies a second electronic device as leaving the multiway call, and the second secret is not exchanged with the second electronic device.

Abstract: Techniques are disclosed relating to multiway communications. In some embodiments, a first electronic device initiates a multiway call between a plurality of electronic devices and exchanges a first secret with a first set of electronic devices participating during a first portion of the multiway call, the first secret being used to encrypt traffic between the first set of electronic devices. The first electronic device receives an indication that first set of participating electronic devices has changed and, in response to the indication, exchanges a second secret with a second set of electronic devices participating during a second portion of the multiway call, the second secret being used to encrypt traffic between the second set of participating electronic devices. In some embodiments, the indication identifies a second electronic device as leaving the multiway call, and the second secret is not exchanged with the second electronic device.

Abstract: A device implementing a system for notifying a first device of availability of a service on a second device includes a processor configured to receive, from the first device of a first user, a first request with respect to whether a service is available on the second device of a second user, and to determine that the service is not available on the second device. The processor is further configured to send, to the first device and in response to the determination, an indication that the service is not available on the second device and an indication of a minimum amount of time before the first device can submit a second request with respect to whether the service is available on the second device. The minimum amount of time is based at least partially on an amount of time that has elapsed since the service was made available to the devices.

Abstract: A device implementing a system for device-relationship based communication includes at least one processor configured to establish, by a first device associated with a first user, a secure communication channel with a second device associated with a second user via a direct wireless connection. The at least one processor is configured to transmit, over the secure communication channel, first device-identifying information to the second device, and receive, over the secure communication channel, second device-identifying information from the second device. The at least one processor is configured to establish a particular type of relationship with the second device, store the second device-identifying information in association with an indication of the particular type of relationship established with the second device, and transmit, to the second device and over the secure communication channel, the indication of the particular type of relationship established with the second device.

Abstract: Techniques are disclosed relating to secure message exchanges. In some embodiments, a first computing device generates an account key associated with a user account shared by a plurality of computing devices. The first computing device signs a public key of the first computing device with the generated account key to produce a digital signature and sends the public key and the digital signature to a first server system for distributing the public key to a second computing device attempting to send an encrypted message to the first computing device. The first computing device sends the account key to an external storage external usable by others of the plurality of computing devices to obtain the account key and use the account key to sign public keys of the other computing devices. The first computing device receives, from the second computing device, the encrypted message encrypted using the public key.

Abstract: A device implementing a system for notifying a first device of availability of a service on a second device includes a processor configured to receive, from the first device of a first user, a. first request with respect to whether a service is available on the second device of a second user, and to determine that the service is not available on the second device. The processor is further configured to send, to the first device and in response to the determination, an indication that the service is not available on the second device and an indication of a minimum amount of time before the first device can submit a second request with respect to whether the service is available on the second device. The minimum amount of time is based at least partially on an amount of time that has elapsed since the service was made available to the devices.

Abstract: Implementations of the subject technology provide for performing, by a device, a request for obtaining information related to a phone authentication certificate (PAC) that was generated for the device, the PAC authenticating that a particular phone number is associated with the device, the request including packets of data. The subject technology receives the information related to the PAC, the information including an indication that the PAC was generated for the device. The subject technology sends, from the device, a request for validating the PAC to a remote server based at least in part on the information related to the PAC. Further, the subject technology receives a confirmation of validating the PAC from the remote server based at least in part on the information related to the PAC.

Abstract: Systems and methods are disclosed for validating an association of a telephone number with a cellular communication device (e.g., validating an assignment of an MSISDN to an IMSI of the cellular communication device). For example, the validating may be performed as part of a process of registering the cellular communication device with a registration server for participation in online communication sessions. In other examples, the validation may be performed for purposes other than registration for participation in online communication sessions. Various mechanisms may be available for performing the validation. The registration server may determine the available mechanisms, and may provide to the cellular communication device an ordered list of mechanisms according to a preferred order. The cellular communication device may improve efficiency of validation by attempting the mechanisms in the preferred order.

Abstract: Techniques are disclosed relating to multiway communications. In some embodiments, a first electronic device initiates a multiway call between a plurality of electronic devices and exchanges a first secret with a first set of electronic devices participating during a first portion of the multiway call, the first secret being used to encrypt traffic between the first set of electronic devices. The first electronic device receives an indication that first set of participating electronic devices has changed and, in response to the indication, exchanges a second secret with a second set of electronic devices participating during a second portion of the multiway call, the second secret being used to encrypt traffic between the second set of participating electronic devices. In some embodiments, the indication identifies a second electronic device as leaving the multiway call, and the second secret is not exchanged with the second electronic device.

Abstract: Systems and methods are disclosed for validating an association of a telephone number with a cellular communication device (e.g., validating an assignment of an MSISDN to an IMSI of the cellular communication device). For example, the validating may be performed as part of a process of registering the cellular communication device with a registration server for participation in online communication sessions. In other examples, the validation may be performed for purposes other than registration for participation in online communication sessions. Various mechanisms may be available for performing the validation. The registration server may determine the available mechanisms, and may provide to the cellular communication device an ordered list of mechanisms according to a preferred order. The cellular communication device may improve efficiency of validation by attempting the mechanisms in the preferred order.