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Nearby Sharing

Tella allows users to securely share files offline, between devices that are in physical proximity to each other.

This feature was primarily designed for users facing internet shutdowns or unreliable connectivity. It's also helpful in situations where mobile networks are saturated or unavailable.

Nearby Sharing in Tella is:

  • Independent of internet connectivity: Transfers work with or without an internet connection, by establishing a direct connection between devices instead of routing through the internet.
  • Cross platform: Nearby Sharing is available on iOS, Android, MacOS, Windows, and Linux, regardless of the device brand or model. Nearby Sharing can be used on any device where Tella is installed.
  • Encrypted: Files are encrypted as they are transferred from one Tella vault to another, protecting the files on monitored or insecure Wi-Fi networks.
  • Private: Tella never saves or stores information about devices you connect to and share files with.

Nearby Sharing will only work for users who are connected to the same Wi-Fi network. This can be either a local Wi-Fi network or a Hotspot.

When to Use Nearby Sharing​

Nearby Sharing is particularly well-suited for:

  • Sharing files during an internet shutdown.
  • High risk scenarios where internet is heavily monitored or censored, and cannot be trusted as a communication channel.
  • During protests or sensitive events, to quickly back up evidence on another person's phone.
  • To increase redundancy of data by backing up files to a personal computer or another device.
  • To migrate files to a new phone.
tip

If you need help understand if Nearby Sharing is well-suited for your use case, contact us!

tip

If you are trying to share files with an organization you are working with, or if you are not in the same physical location as the person you want to exchange files with, Tella's server connections may be better-suited than Nearby Sharing. Tella supports the following connections:

How to use Nearby Sharing​

To get started, tap the Nearby Sharing button under the Connections section on the Tella Homescreen. If you do not see the Nearby Sharing button on your homescreen, make sure it is enabled in Settings ⚙️ > Connections > Nearby Sharing

In order to use the feature, the sender and receiver must be on the same Wi-Fi network. You can share files between two mobile devices (Android or iOS) or from a mobile device to a computer. There are 2 ways to connect your devices though Wi-Fi:

  1. Using a local network, such as the Wi-Fi at your home or work, or a public Wi-Fi network.
  2. Setting up a Hotspot on a device, and making sure both the sender and receiver have joined that Wi-Fi network. The device that created the Hotspot Wi-Fi network can be one of the two devices exchanges files while another device connects to it, or two devices can connect to a Hotpost Wi-Fi network created on a third device.

Tella will guide users through each step of the file transfer.

note

Some public Wi-Fi networks (for example in some hotels or coffee shops) might not work due to their configuration preventing direct connections between devices. In those cases, create a hotspot.

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Nearby Sharing does not work if either of the devices is connected to a VPN.

Technical security measures​

Nearby Sharing is designed to work safely even on insecure or monitored Wi-Fi networks. It relies on the following technical security measures:

  • Certificate and PIN-based authentication: connecting requires both a PIN and certificate verification. This happens automatically when scanning a QR code, or manually if QR scanning isn't available; in that case, both devices display the certificate's fingerprint (a hash), and users confirm that the same fingerprint appears on both screens before continuing.
  • Mutual TLS (mTLS): every connection uses HTTPS with a unique, self-signed certificate generated for each device, for each session. Both devices verify each other's certificate before any file is exchanged — the sending device verifies the receiving device, and the receiving device also verifies the sender. This protects the connection against man-in-the-middle attacks.
  • Session-based, ephemeral certificates: certificates are generated for a single session and discarded once the transfer ends. Certificates are never reused or stored long-term.
  • Rate-limited connections: repeated invalid connection attempts are blocked, to protect against brute-force guessing.
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Nearby Sharing was reviewed as part of Tella's regular independent security audits.

Technical readers can find the full protocol specification in the Tella-P2P-Protocol repository.

Platform availability​

Nearby Sharing is available for Tella Android, Tella iOS and Tella Desktop.