dart_cid 0.1.0

A dart-lang implementation for creating self-describing content-addressed identifiers for distributed systems (CIDs).

dart_cid

A dart implementation of cid ("content id") = human-friendly (readable/typeable) unique ID for distributed/decentralised systems.

Why 🤷

In a database that is distributed, creating IDs that reference records with virtually no risk of collision is a must. We need a standardized way of creating IDs for both the server and the client-side of our app, in an offline-first approach.

As we are using Flutter for developing our application, we needed a way to create these IDs using the Dart language.

What? 🔐

If you are a newbie when it comes to cids and how they are applicable to distributed scenarios, we highly encourage you to check the dwyl/cid repo. Although it was made for Elixir, you can find more about real-life situations of how these are used, especially with IPFS. And yes, it will answer the obvious question of Why are you not using UUIDs? 😉

How? 💡

Using this package is as easy as pie. You just need an input string that will be hashed and used to create a corresponding cid. This cid will be, as the name implies, the content identifier - something that will identify that string.

Let's see it in action.

Installing

Add the following to your pubspec.yaml file, under dependencies.

dependencies:
  dart_cid: ^0.1.0

and run the following command to fetch the dependencies.

flutter pub get

Usage

Creating a CID

Now just call the createCid() function! You may decide what multibase you want to use. This library tries to support the official/default bases. If you see one that's missing, do open an issue.

import 'package:dart_cid/dart_cid.dart';

String input = 'hello world';
final output = CID.createCid(input, Multibase.base58btc);

and you're done! 🎉 You just created your own fancy cid!

Note

Every cid generated with this package will use the raw codec and will be hashed using the sha2-258 algorithm. You may choose which base you want to encode it as, though.

Decoding a CID

If you're given a CID and you wish to decode it, you can use the decodeCid() function.

CIDInfo cidInfo = decodeCid("some_cid");

This function will return an instance of CIDInfo, holding relevant information of the provided CID.

Considerations

The previous code snippet will yield the following cid.

zb2rhj7crUKTQYRGCRATFaQ6YFLTde2YzdqbbhAASkL9uRDXn

We can use the IPFS cid inspector to see the information that is hashed into the string.

Open https://cid.ipfs.tech/#zb2rhj7crUKTQYRGCRATFaQ6YFLTde2YzdqbbhAASkL9uRDXn and see it for yourself!

As you can see, the cid contains leading identifiers that clarify which representation is used, along with the content-hash. It includes:

• multibase prefix which specifies the encoding of the cid.
• cid version
• multicodec which indicates the format of the target content.

For more information about the format of cids, check this link -> https://docs.ipfs.tech/concepts/content-addressing/#cid-versions

I need help! ❓

If you have some feedback or have any question, do not hesitate and open an issue! We are here to help and are happy for your contribution!

License

MIT