Vade Evan

About

This crate allows you to use to work with DIDs and zero knowledge proof VCs on Trust and Trace. For this purpose two VadePlugin implementations are exported: VadeEvan and SubstrateDidResolverEvan.

VadeEvan

Responsible for working with zero knowledge proof VCs on Trust and Trace.

Implements the following VadePlugin functions:

• vc_zkp_create_credential_schema
• vc_zkp_create_credential_definition
• vc_zkp_create_credential_proposal
• vc_zkp_create_credential_offer
• vc_zkp_request_credential
• vc_zkp_create_revocation_registry_definition
• vc_zkp_update_revocation_registry
• vc_zkp_issue_credential
• vc_zkp_revoke_credential
• vc_zkp_request_proof
• vc_zkp_present_proof
• vc_zkp_verify_proof
• run_custom_function

SubstrateDidResolverEvan

Supports creating, updating and getting DIDs and DID documents on substrate, therefore supports:

• did_create
• did_resolve
• did_update

Signing substrate requests

As the did resolver instance needs to sign its requests against substrate, a remote endpoint for signing has to be provided. The DID resolver will sign requests for did_create and did_update. A signing endpoint has to be passed with the config argument in the constructor, e.g.:

use vade_evan::{
    resolver::{ResolverConfig, SubstrateDidResolverEvan},
    signing::{LocalSigner, Signer},
};
let signer: Box<dyn Signer> = Box::new(LocalSigner::new());
let resolver = SubstrateDidResolverEvan::new(ResolverConfig {
    signer,
    target: "127.0.0.1".to_string(),
});

signing_url will be called with a POST request. The messages that should be signed is passed to the server alongside a reference to a key like this:

{
    "key": "some-key-id",
    "type": "some-key-type",
    "message": "sign me please"
}

Two types of of responses are supported. Successful signing results are give in this format:

{
  "messageHash": "0x52091d1299031b18c1099620a1786363855d9fcd91a7686c866ad64f83de13ff",
  "signature": "0xc465a9499b75eed6fc4f658d1764168d63578b05ae15305ceedc94872bda793f74cb850c0683287b245b4da523851fbbe37738116635ebdb08e80b867c0b4aea1b",
  "signerAddress": "0x3daa2c354dba8d51fdabc30cf9219b251c74eb56"
}

Errors can be signaled this way:

{
    "error": "key not found"
}

Compiling vade-evan

"Regular" build

No surprise here:

cargo build --release

Default Features

By default features did, native, and vc-zkp are used. So everything included and available for usage in other Rust libraries.

Features can be omitted. This mostly concerns, the vc-zkp feature, as it can be dropped without affecting the did functionality. did can be omitted as well but will most probably limit usability vc-zkp functionalities as this relies on did logic for some parts of its logic.

In short: Use either did and vc-zkp together (default) or just did.

Command Line Interface

To enable the cli just add the feature cli to the feature set:

cargo build --release --features cli

You can now use the vade-evan cli. Get started by having a look at the help shown after calling it with:

./target/release/vade_evan_cli

WASM

To compile vade-evan for wasm, use wasm pack.

You can specify to use only did feature or to use did and vc-zkp. The following examples will use both features.

Also you have to specify whether to build a browser or a nodejs environment.

nodejs:

wasm-pack build --release --target nodejs -- --no-default-features --features did,vc-zkp,wasm

browser:

wasm-pack build --release --target web -- --no-default-features --features did,vc-zkp,wasm

Features for building