What is AT Protocol (Authenticated Transfer Protocol)?

If you’re wondering what the AT Protocol (Authenticated Transfer Protocol, or atproto) is, you’ve come to the right place. In the article below, we’ll review Bluesky’s new protocol and how it works, and we will present its key features while focusing on the essentials.

We’ll also present a few of the AT Protocol’s limitations and examine the ways Bluesky is working to improve its decentralized social network. Finally, we’ll address some frequent questions on the topic.

What is the AT Protocol?

Bluesky’s AT Protocol (Authenticated Transfer Protocol) is a decentralized social networking framework. It allows users to control their own data and connections without relying on a single company or server and enables interaction across different social platforms.

Another key feature of the AT Protocol is data portability, which makes it easy for users to move their data between different providers. Users can manage their data as they see fit and take their online identity with them without sticking to one service.

How does the AT Protocol work?

Unlike traditional social media, where one company owns everything, AT Protocol allows different platforms (or “instances”) to work together while allowing users to choose where to connect.

The protocol ensures each instance can operate independently but still interact smoothly with others through a shared set of rules. This concept is called “federation” and lies at the heart of atproto, ActivityPub (used by Mastodon), Diaspora, and similar protocols.

When you create an account on a network that uses the AT Protocol, you’re not just signing up with that service—you’re establishing a personal, decentralized identity. This can be used across various platforms, so you don’t need to start over if you decide to change services.

The PLC.Directory plays a key role in this system by acting as a directory for these decentralized identities, mapping them to public key addresses. This ensures your identity remains consistent as you move between platforms supporting atproto.

A public key address in the AT Protocol is like a unique online ID that links to your digital profile. It helps prove who you are and lets you connect with others securely across different platforms without needing to rely on one central company or service. Basically, it’s your identity in the massive “contact list” that is the PLC Directory.

Key features of the AT Protocol

The AT Protocol has a few key features you should know about:

• Decentralized identity: Users control their identities without being tied to a specific platform or company. The AT Protocol uses decentralized identifiers (DIDs) to ensure that your identity stays yours, no matter your platform.
• Interoperability: Different platforms can talk to each other by exchanging schematic and semantic information. You can follow and interact with people on other atproto platforms, without needing to be on the same service.
• Customizable content algorithms: You can choose how your feed works. Instead of being stuck with an app’s default settings, the AT Protocol lets you customize the content you see, giving you more control over your experience.
• Data portability: Users can move their data freely between social networks. This means that your posts, followers, and other data can be easily transferred if you switch to a new platform, making you less likely to be locked into one service.
• Open development: The protocol is being developed transparently and is open-source, allowing anyone to contribute and potentially improve the ecosystem.

Challenges and limitations of the AT Protocol

Despite its innovative approach, critics have pointed out some limitations that currently prevent Bluesky from being a truly decentralized platform, such as:

• Centralized control: While the AT Protocol aims for decentralization, Bluesky still controls key infrastructure, including the Big Graph Service (BGS), which manages data and content distribution.
• Identity system issues: Identity depends on Bluesky-controlled servers, meaning the protocol doesn’t fully decentralize identity management. Users may lose control over their accounts or data if Bluesky enforces bans or other restrictions.
• Limited incentives for alternatives: Bluesky’s dominance over the AT protocol reduces incentives for competitors to develop alternative instances, leaving the system reliant on Bluesky’s servers rather than a truly federated, open network.

To add to the last point, you could look at Bluesky’s expansion as a repeat of the old Internet. Everyone can make their own website, but not everyone wants to create one or handle hosting and associated costs. As a result, the Internet became increasingly centralized, making it feel like you’re only switching between the same 8-10 apps and websites every day.

As for the others, Bluesky is working towards improving its decentralization efforts. For example, it’s considering handing over control of its PLC directory to an independent organization similar to ICANN, which manages the global domain name system (DNS), to ensure a neutral, decentralized system that isn’t controlled by any one entity.

What is AT Protocol? FAQs

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