Following our reveal last month, today we announce the launch of the Blockstream Satellite API Beta, offering anyone the chance to broadcast data via our satellite network. Fees are paid using Lightning testnet (yes, that means free broadcasts!) and after a period of successful testing, the satellite API will switch to mainnet to become one of the world’s first bitcoin-powered satellite services!

What is the Blockstream Satellite API?

The Blockstream Satellite API provides developers with an easy-to-use RESTful API to submit messages for broadcast. The API is totally “data agnostic.” Whether broadcasting secure messaging, alternative blockchains, or a global podcast, the Blockstream Satellite API supports it.

For non-developers, we’re also providing an easy-to-use portal to submit simple messages via the Blockstream website, with the same Lightning payment support.

Thanks to our Phase 2 expansion, messages can be received by the vast majority of the world’s population. All that is needed to receive a broadcast is a satellite dish (a TV satellite dish will suffice), a few low-cost components, and a computer. Broadcasts can be received anywhere with a line of sight to one of our four geosynchronous satellites, completely free of charge.

How Does It Work?

Presently, Blockstream Satellite is broadcast-only. The fee to send data is variable and broadcasts are prioritised by the amount paid per byte sent. In times of heavy traffic, this creates a fee market, similar to how transactions compete for inclusion in Bitcoin blocks. The maximum message size is limited to ensure that a message can be transmitted within ten seconds if it is submitted with the highest current bid per byte.

Developers using the Blockstream Satellite API are expected to handle their own encryption, fragmentation, and reassembly of large messages, according to each application’s needs. The Satellite API service provides only the low-friction transmission of data through the Blockstream Satellite network.

Privacy Features

Blockstream Satellite features a number of important features that support varying levels of privacy for broadcasts:

• Supports encryption: While broadcast data may be received by all Blockstream Satellite users, a developer can create an application using public key encryption and distribute keys only to the intended recipient(s). This ensures only a specific user or group of users can decrypt the received data. To demonstrate this capability, an example application is included with Blockstream Satellite v1.1.0 that allows secure file transmission using GPG.
• Out-of-band: Data is sent out-of-band from the internet, via a broadcast medium, further improving the privacy already achieved by modern cryptographic techniques.
• Lightning payments: With the right precautions, using the Lightning Network as a payment method for the service enables a further level of privacy, disconnecting the payment source from the destination.

Get started

If you’re a developer, check out our new technical documentation and example applications. The API implementation itself is available here.

For non-developers, get your message queued by submitting your data to the Blockstream API page and paying the fee via Lightning testnet.

The API service is currently in beta, so we’re really looking forward to your feedback. Don’t hesitate to let us know any changes or new features you’d like to see via Github.