Vade - evan.network Plugins

About

This project is providing two plugins to be used with the vade library. These plugins offer functionalities to work with VCs and DIDs on evan.network.

Usage

Plugins from this project can be used within the vade library as described in its own documentation. To give you a jump start, here is how you can retrieve VC documents:

extern crate vade;
extern crate vade_evan;

use vade::Vade;
use vade_evan::plugin::rust_vcresolver_evan::RustVcResolverEvan;

const EXAMPLE_VC_NAME_REMOTE: &str = "vc:evan:testcore:0x6e90a3e2bf3823e52eceb0f81373eb58b1a0a238965f0d4388ab9ce9ceeddfd3";

#[tokio::test]
async fn can_fetch_a_vc_document() {
    let rde = RustVcResolverEvan::new();
    let mut vade = Vade::new();
    vade.register_vc_resolver(Box::from(rde));

    let _vc = vade.get_vc_document(&EXAMPLE_VC_NAME_REMOTE).await.unwrap();
}

Plugins

Plugins are described below shotly, for more details see respective API documentation.

VC Resolver

Allows to work with VCs on evan.network, currently includes:

• retrieving VCs
• validating VCs, which will
  • check proof (if attached)
  • check credentialStatus online (if attached)
• creating VCs

Retrieving VCs

Existing VCs from evan.network can be retrieved with vade's get_vc_document function:

use vade::Vade;
use vade_evan::plugin::rust_vcresolver_evan::RustVcResolverEvan;

async fn example() {
    let vcr = RustVcResolverEvan::new();
    let mut vade = Vade::new();
    vade.register_vc_resolver(Box::from(vcr));

    let vc = vade.get_vc_document("vc:evan:testcore:0x75956ef9b3ea7d7230cf007b8ee042bcaa2a4dad8c043fa77ecf51262ee4f7a9").await.unwrap();
}

Result is returned as a JSON String and can easily be parsed with libraries like serde_json for further processing, e.g.:

let parsed: Value = serde_json::from_str(&vc).unwrap();

Validating VCs

Taken from our tests:

use vade::Vade;
use vade::plugin::rust_storage_cache::RustStorageCache;
use vade_evan::plugin::rust_vcresolver_evan::RustVcResolverEvan;

async fn example() -> std::result::Result<(), Box<dyn std::error::Error>> {
    // create a vc resolver with attached did resolver in a vade instance
    let vcr_didr = RustStorageCache::new();
    let mut vcr_vade = Vade::new();
    vcr_vade.register_did_resolver(Box::from(vcr_didr));
    // add did document to vcr's did resolver
    let did_id = "did:evan:testcore:0x0ef0e584c714564a4fc0c6c367edccb0c1cbf65f";
    let did_document = "{...}";
    vcr_vade.set_did_document(&did_id, &did_document).await?;
    let mut vcr = RustVcResolverEvan::new();
    vcr.vade = Some(Box::from(vcr_vade));

    // create vade to work with, attach vc resolver
    let mut vade = Vade::new();
    vade.register_vc_resolver(Box::from(vcr));

    // test VC document
    let vc_name = "vc:evan:testcore:0x8b078ee6cfb208dca52bf89ab7178e0f11323f4363c1a6ad18321275e6d07fcb";
    let vc_document = "{...}";
    let vc_result = vade.check_vc(&vc_name, &vc_document).await;
    match vc_result {
        Ok(_) => (),
        Err(e) => panic!(format!("{}", e)),
    };
    Ok(())
}

Note that the setup for the RustVcResolver instance differs a bit, as we

• create a separate Vade instance
• configure a DidResolver for it in this case an in-memory resolver for our test DID
• register it as vade in our RustVcResolver instance

This allows us to validate the proof property in our VC document.

Creating VCs

Creating a VC currently has three requirements:

• an evan.network identity for the VC issuer, which means, we also have
  • a DID document for the issuer of our VC
  • a 64B private key as str, used to create the proof property (of course not IN the DID document ;))
  • a way to identify this key, as the ethereumAddress of it is IN the DID document
• an id for the VC - as the VCs created with vade-evan are currently not stored onchain, we cannot rely on automatic ID generation (id can currently be anything, but you should try to avoid reusing IDs to avoid overriding your documents locally)

As an example take this test function:

use serde_json::Value;
use vade_evan::plugin::rust_vcresolver_evan::{
    RustVcResolverEvan,
    VC_DEFAULT_TYPE,
    VC_W3C_MANDATORY_CONTEXT,
};

async fn vc_resolver_can_create_new_vcs() -> std::result::Result<(), Box<dyn std::error::Error>> {
    // issuer of the new VC
    let veri_issuer = "did:evan:testcore:0x0ef0e584c714564a4fc0c6c367edccb0c1cbf65f";
    // verification method of the VC (can be considered "key id" for the key used to create proof)
    let veri_method = "did:evan:testcore:0x0ef0e584c714564a4fc0c6c367edccb0c1cbf65f#key-1";
    // Ethereum private key used to create proof
    let veri_pkey = "01734663843202e2245e5796cb120510506343c67915eb4f9348ac0d8c2cf22a";
    // sample data, `id` is required, `credentialSubject` is optional and holds tests data
    let partial_vc_data =r###"
    {
        "id": "foo-bar-vc",
        "credentialSubject": {
            "foo": "bar"
        }
    } 
    "###;

    let vcr = RustVcResolverEvan::new();

    let vc: String = vcr.create_vc(partial_vc_data, &veri_method, &veri_pkey).await.unwrap();

    let parsed: Value = serde_json::from_str(&vc).unwrap();

    assert!(parsed["credentialSubject"]["foo"].as_str() == Some("bar"));
    assert!(parsed["@context"].as_array().unwrap().len() == 1);
    assert!(parsed["@context"].as_array().unwrap().iter().any(|v| v == VC_W3C_MANDATORY_CONTEXT));
    assert!(parsed["type"].as_str() == Some(VC_DEFAULT_TYPE));
    assert!(parsed["issuer"].as_str() == Some(veri_issuer));
    assert!(parsed["validFrom"].as_str() != None);
    assert!(parsed["proof"].as_object() != None);

    Ok(())
}

Have a look at the assert block at the end of the test. Here you can see the properties, that are added automatically:

• @context
• type
• issuer
• validFrom
• proof

These are added automatically if not provided in partial_vc_data.

DID Resolver

Allows to work with DIDs on evan.network, currently includes:

• retrieving DIDs

Retrieving DIDs

Fetching DIDs via RustDidResolver fetches them from evan.network and returns them as str, e.g.:

use vade::Vade;
use vade_evan::plugin::rust_didresolver_evan::RustDidResolverEvan;
let rde = RustDidResolverEvan::new();
let mut vade = Vade::new();
vade.register_did_resolver(Box::from(rde));

let did = vade.get_did_document("did:evan:testcore:0x0ef0e584c714564a4fc0c6c367edccb0c1cbf65f").await.unwrap();