alright protocol devs, some wonky bits: we revisited the recent service auth JWT harmonization proposal, and have a revision up that sticks with a single string 'aud' field. also touches on issuer 'kid', and makes 'lxm' mandatory for XRPC endpoints.
proposals/0014-service-auth-revised at main · bluesky-social/proposals
github.comApr 21, 2026 at 2:14 AM
AIP: Agent Identity Protocol for Verifiable Delegation Across MCP and A2A
AI agents increasingly call tools via the Model Context Protocol (MCP) and delegate to other agents via Agent-to-Agent (A2A), yet neither protocol verifies agent identity. A scan of approximately 2,000 MCP servers found all lacked authentication. In our survey, we did not identify a prior implemented protocol that jointly combines public-key verifiable delegation, holder-side attenuation, expressive chained policy, transport bindings across MCP/A2A/HTTP, and provenance-oriented completion records. We introduce Invocation-Bound Capability Tokens (IBCTs), a primitive that fuses identity, attenuated authorization, and provenance binding into a single append-only token chain. IBCTs operate in two wire formats: compact mode (a signed JWT for single-hop cases) and chained mode (a Biscuit token with Datalog policies for multi-hop delegation). We provide reference implementations in Python and Rust with full cross-language interoperability. Compact mode verification takes 0.049ms (Rust) and 0.189ms (Python), with 0.22ms overhead over no-auth in real MCP-over-HTTP deployment. In a real multi-agent deployment with Gemini 2.5 Flash, AIP adds 2.35ms of overhead (0.086% of total end-to-end latency). Adversarial evaluation across 600 attack attempts shows 100% rejection rate, with two attack categories (delegation depth violation and audit evasion through empty context) uniquely caught by AIP's chained delegation model that neither unsigned nor plain JWT deployments detect.
Authenticated XRPC Calls in Lexicon Garden - Nick's Blog
ATProtocol OAuth pairs effortlessly with Lexicon Garden to make it easy for developers to experiment with authenticated XRPC endpoints.
OAuth Improvements - AT Protocol
We've been making improvements to the end-user and developer experiences with atproto OAuth.
Updated Auth Scopes Proposal · bluesky-social atproto · Discussion #4013
This is a discussion thread for the July 2025 Auth Scopes proposal
Local First Auth Specification
Technical specification for Local First Auth Specification
OAuth Patterns - AT Protocol Docs - AT Protocol
Auth for AT Protocol application developers.
OAuth Patterns - AT Protocol Docs - AT Protocol
Auth for AT Protocol application developers.
Alex Albert on Twitter / X
We just published a near-term development roadmap for the model context protocol (MCP)Some highlights:- Remote support (and auth!)- Reference implementations- Better package management- Agent support pic.twitter.com/SflJi1RapH— Alex Albert (@alexalbert__) January 2, 2025
oauth-client-metadata.json | AT Protocol Community Wiki
A community-maintained wiki for the AT Protocol ecosystem
Authenticated Transfer: Architecture Overview
Authenticated Transfer (AT) is a collection of protocol components that together provide a generic framework for interoperable social web applications, using global aggregations of interlinked, self-certifying data records. This informational document provides an overview of the entire system, as implemented in late 2025. Some of those components may be in scope as work for the IETF, while other components may not. Many components are general-purpose and may find use outside of the context of AT. The intent of this document is to provide context for how all the components can fit together for certain use cases.
Service Auth | Bluesky
There are currently two "types" of auth supported in the atproto network: client-server auth and service-to-service auth.
Cross-App Authentication on AT Protocol
We recently built cross-app authentication between Roomy and OpenMeet using AT Protocol service auth JWTs. The idea came from @erlend.sh (his writeup), @zicklag.dev introduced me to PDS service auth, and @meri.garden contributed reviews. I made the implementation in both apps: A user logs into Roomy, navigates to an OpenMeet event, and is silently authenticated and able to use their account on OpenMeet without a second login. Full technical writeup: Cross-App Authentication on AT Protocol I’m ...
XRPC requests between atproto servers are authenticated using JWTs. There are some inconsistencies in how OAuth permissions, PDS proxy headers, and JWTs all represent the "audience" of these tokens. This proposal gives background and describes a rough solution. Looking for rapid feedback!
proposals/0013-service-auth-refs at main · bluesky-social/proposals
github.com
