Advanced security protocol for broadcasting and synchronizing shared folders over local area network

A non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to:

• send, by a first client device on a local area network, an announcement message to a second client device on the local area network, the announcement message comprising a first secure identifier that uniquely identifies a shared content item associated with one or more user accounts on a content management system, the first secure identifier being generated by the first client device using a shared secret key;
• receive, by the first client device on the local area network, a synchronization message requesting to synchronize local copies of the shared content item stored on the first client device and the second client device, the synchronization message comprising a second secure identifier that uniquely identifies at least one of the second client device or the shared content item, the first secure identifier and the second secure identifier being both based on the shared secret key;
• based on the first secure identifier and the second secure identifier, verify, by the first client device, that the second client device is authorized to access the shared content item;
• and
• synchronize, by a connection over the local area network between the first client device and the second client device, the local copies of the shared content item stored on the first client device and the second client device.

A method comprising:

• receiving, by a first client device on a local area network, an announcement message sent by a second client device on the local area network, the announcement message comprising a first secure identifier that uniquely identifies a shared content item associated with one or more user accounts on a content management system, the first secure identifier being generated by the first client device using a shared secret key;
• based on the announcement message, determining, by the first client device, that the second client device has a local copy of the shared content item;
• sending, by the first client device to the second client device on the local area network, a synchronization message requesting to synchronize the shared content item between the first client device and the second client device, the synchronization message comprising a second secure identifier that uniquely identifies at least one of the first client device or the shared content item, the first secure identifier and the second secure identifier being both based on the shared secret key;
• and
• synchronizing, via a connection over the local area network between the first client device and the second client device, the shared content item between the first client device and the second client device.