Data Issuer

The Data Issuer only needs to follow this step for integration with the zkPass Service:

• Providing REST API for user data retrieval

Sample Implementation

Sample codes for the Data Issuer implementation follow. Each step is explained in detail in the subsections. The code is also available on the zkpass-sdk repo, as shown here:

https://github.com/gl-zkPass/zkpass-sdk/blob/main/rust/zkpass-demo/src/data_issuer.rs

use serde_json::Value;
use std::collections::HashMap;
use std::io::prelude::*;
use tracing::info;
use zkpass_client::core::KeysetEndpoint;
use zkpass_client::interface::{ZkPassClient, ZkPassUtility};

use crate::constants::ISSUER_PRIVKEY;

//
//  Simulating the REST call to the Data Issuer
//
pub struct DataIssuer;

//
//  Simulating the Data Issuer
//
impl DataIssuer {
    //
    // This function simulates the Data Issuer's get_user_data_token REST API
    //
    pub fn get_user_data_tokens(
        &self,
        zkvm: &str,
        data_files: HashMap<String, String>,
    ) -> HashMap<String, String> {
        //
        //  Data Issuer's integration points with the zkpass-client SDK library
        //

        //
        // Step 1: Instantiate the zkpass_client object
        //
        let zkpass_client = ZkPassClient::new("", None, zkvm);

        //
        // Step 2: Call the zkpass_client.sign_data_to_jws_token.
        //         This is to digitally-sign the user data.
        //
        data_files
            .iter()
            .map(|(data_tag, data_file)| {
                let data = self.read_user_data_token(data_file);
                let data_token = self.sign_user_data_token(&zkpass_client, data);
                (data_tag.clone(), data_token)
            })
            .collect()
    }

    fn sign_user_data_token(&self, zkpass_client: &ZkPassClient, data: Value) -> String {
        let kid = String::from("k-1");
        let jku = String::from(
            "https://raw.githubusercontent.com/gl-zkPass/zkpass-sdk/main/docs/zkpass/sample-jwks/issuer-key.json"
        );
        let ep = KeysetEndpoint { jku, kid };
        zkpass_client
            .sign_data_to_jws_token(ISSUER_PRIVKEY, data, Some(ep))
            .unwrap()
    }

    fn read_user_data_token(&self, data_file: &String) -> Value {
        let mut data_content =
            std::fs::File::open(data_file).expect("Cannot find the user data file");
        let mut data = String::new();
        data_content
            .read_to_string(&mut data)
            .expect("Should not have I/O errors");
        info!("data={}", data);

        let data: Value = serde_json::from_str(&data).unwrap();
        data
    }
}