CIDStable
Content Identifiers
Identifiers for addressing resources by their contents: essentially a hash with limited metadata.
DASL
say it like “dazzle”Data-Addressed Structures & Links
What is this?
DASL (“dazzle”) is a small set of simple, standard primitives for working with content-addressed, linked data. It builds on content addressing, a proven approach used in Git and IPFS to create reliable content identifiers (known as CIDs) through cryptographic hashing. The design is heavily inspired by the IPFS universe, but simplified to improve interoperability, decrease costs, and work well with the web.
Systems can verify they received exactly what they asked for and avoid downloading the same content twice. The linked data part lets you link to stuff by its hash. You can build very big graphs with these primitives, such as the graph behind Bluesky.
Our priorities
- Pave the cowpaths We support what people solving real-world problems actually use, over engineering ideals or theoretical purity.
- Extensibility vs optionality Extension points now, but we deliberately don’t use their full range. Options cost everyone.
- Don’t make me think Grab it off the shelf and it works. Nothing weird, no impedance mismatch.
- Lightweight loading Some people like JavaScript, others don’t. Shipping small code to the browser is critical.
- Unix philosophy Tiny specs that compose in simple ways and can be implemented independently.
This is intended to work for the community, to grow support for what we need. If you have thoughts, don’t be shy and submit an issue! No stupid questions, don’t assume everyone else has context that you don’t. If this page isn’t enough to understand DASL, then we’re the ones who screwed up.
How
DASL uses content identifiers to create a shared namespace for content (raw data) and metadata (structured documents), so documents can easily reference data and other documents.
Because identifiers are content-addressed with SHA-256, anything in the namespace can be hosted anywhere and retrieved (RASL) from anywhere. Data is self-certifying, so you can build open systems without trusting where it came from.
Other specs help you build larger systems, like MASL for document schemas and CAR for bundling for transfer or storage. Together, they let you build coherent linked data graphs that scale and travel easily.
{
// Some metadata
"author": "Samuel Johnson",
"ts": "2024-05-03T03:22:04.000Z",
"type": "create",
"path": "/foo/bar/baz",
// Now we reference a blob of data, by hash.
// CIDs can be stored natively as bytes in documents, for efficiency.
"data": bafkreifn5yxi7nkftsn46b6x26grda57ict7md2xuvfbsgkiahe2e7vnq4,
// We can reference other documents as well.
// The first few bytes of this CID tell us (1) that it points to a
// structured CBOR document, not a blob of raw data, and (2) the hash
// of that document, so we know whether we already have it stored.
"author_profile": bafyreibgiedphoxy4pmqv2jmdm5atqq4dbe5ujtm3ebs6ue7gbwlec5do4
}Implementations
Here are some libraries to get started today. See a missing library? File an issue or PR.
JS / TS
- @dasl/rasl: RASL handler for ExpressJS.
- @dasl/tiles: Web Tiles loader, CLI, and server.
- atcute: lightweight packages for the ATmosphere.
- Helia: modular, browser-friendly IPFS.
Python
- carbox: CAR v1 reader and writer.
- dag-cbrrr: fast DAG-CBOR.
- python-libipld: Python wrapper around Rust.
Go
Rust
- dasl: CIDs and DRISL.
- ipld-core: fast Rust implementation.
- rust_cid_npm: tiny library, CLI, and npm package.
Other languages
- elixir-dasl (Elixir): CID, DRISL, and CAR.
DASL is a strict subset of IPFS CIDs and IPLD, so any library that supports CIDv1 and DAG-CBOR can read DASL data, too. Check each library’s results in the compliance matrix, or run the test suite yourself.
Specifications
Maturity levels: Hot New Stuff Stabilising Stable
Foundations
Identifiers, encoding, bundling, and metadata.
DRISLStable
Deterministic Representation for Interoperable Structures & Links
Deterministic CBOR, so the same data always gets the same CID, with CIDs as compact links.
CARStable
Content-Addressable aRchives
A set of content-addressed resources in one stream, with a header that describes it.
MASLStabilising
Metadata for Arbitrary Structures & Links
CBOR metadata documents for self-contained, self-certified content distribution.
BDASLStabilising
Big DASL
A hash type for large files with streaming verification. Not in browsers by default.
Retrieval & Discovery
Getting content, and finding out where it lives.
RASLStabilising
Retrieval of Arbitrary Structures & Links
A URL scheme for DASL resources, plus a simple HTTP-based way to fetch them.
FISLHot New Stuff
Finding Internet Structures & Links
An HTTP lookup API that maps CIDs to where you can get them, and who announced them.
ATFISLHot New Stuff
Content Discovery with the AT Protocol
Publishers announce download locations in their AT repos; indexers gather them for FISL.
Media
Video and audio, provenance, and more.
MUXLStabilising
Media Uniform eXact Layout
Stable identifiers for video and audio. It’s like DRISL for MP4 files!
S2PAStabilising
Simple Standard for Provenance and Authenticity
C2PA media signing, extended for decentralized identity systems.
PFPStabilising
Perceptual Fingerprint
Perceptual hashes that point at similar content rather than one exact file.
Web Tiles
Small, safe, composable web apps.
Web TilesStabilising
Composable web docs and apps that run safely anywhere: social media, chat, agents, and malleable software.
Tiles ProtocolsHot New Stuff
How tiles get capabilities and talk to whatever environment they’re embedded in.
Data PassingHot New Stuff
Tiles Protocol
Passing data to and from tiles, so they fit into any environment.
Informative
Guidance and project documents.
What to consider when using DASL with IPFS systems, especially DHT and Bitswap ones.
How the DASL Project works: stewards, editors, maturity levels, and new specs.