Refresh service

Users can utilize the refresh service to renew expired credentials. This server operates as a proxy intermediary between data providers and user credentials. The server's behavior is contingent on the credential type and subject, allowing it to discern and engage with the appropriate data provider to retrieve relevant data. Then, it builds a new credential request, configuring it accordingly, and forwards this request to the issuer node for the issuance of a fresh credential.

It is important to note that the refresh service imposes a constraint on non-merklized credentials. In cases where values are stored within index slots and remain unaltered by the data provider, the service will return an error. This occurs because merkle trees do not accommodate credentials with equal index slots.

To run this service, users should manage two configurations: one in a .env file and another in config.yaml. .env configuration is used for configure the server, config.yaml configuration is used for configure HTTP data provider.

1. .env file:

Config Name	Description	Required	Default Value	Format	Example
SUPPORTED_ISSUERS	A list of supported issuers with their corresponding node URLs.	Yes	-	issuerDID=issuerNodeURL,...	did:example:issuer1=https://issuer1.com,did:example:issuer2=https://issuer2.com or *=https://common.issuer.com>
IPFS_GATEWAY_URL	The URL of the IPFS gateway.	No	https://ipfs.io	URL	https://ipfs.example.com
SERVER_HOST	The server host.	No	localhost:8002	Host:Port	localhost:8002
HTTP_CONFIG_PATH	The path to the HTTP provider configuration.	No	config.yaml	Path	/path/to/http/config
SUPPORTED_RPC	Supported RPC endpoints for different blockchain chains.	Yes	-	chainID=RPC_URL,...	80002=https://amoy.infura,137=https://main.infura
SUPPORTED_STATE_CONTRACTS	Supported state contracts for different blockchain chains.	Yes	-	chainID=contractAddress,...	80002=0x123abc...,137=0x456def...
CIRCUITS_FOLDER_PATH	The path to the circuits folder.	No	keys	Path	/path/to/circuits
ISSUERS_BASIC_AUTH	Basic authentication credentials for issuer nodes.	No	-	issuerDID=user:password,...	did:example:issuer1=admin:pass123,did:example:issuer2=guest:pass321 or *=common:pass987
SUPPORTED_CUSTOM_DID_METHODS	Register custom networks for DID methods.	No	-	JSON Array	[{"blockchain":"linea","network":"testnet","networkFlag":"0b01000001","chainID":59140}]

2. config.yaml for configure HTTP request to data providers: Example:

   urn:uuid:069dccf5-0d79-49fd-aed5-e7301956d0f4:
     settings:
       timeExpiration: 5m
     provider:
       url: https://api.polygonscan.com/api
       method: GET
     requestSchema:
       params:
         module: account
         action: balance
         address: "{{ credentialSubject.address }}"
         apikey: API_KEY
       headers:
         Content-Type: application/json
     responseSchema:
       type: json
       properties:
         result:
           type: string
           match: credentialSubject.balance

   First, we create a data provider for the credential type (in our case, urn:uuid:069dccf5-0d79-49fd-aed5-e7301956d0f4).

   settings section:

   timeExpiration: This defines how long a credential must remain valid after a refresh.
   

   provider section:

   url: The provider URL.
   method: The type of HTTP request to the URL.
   

   requestSchema describes the format of a request to the data provider:

   params: A key-value list that will be substituted into provider.url. You can use the template value {{ credential.field }} to substitute a value from the user's credentials.
   headers: A list of headers that will be added to the request.
   

   responseSchema describes how to convert the data provider's response to a credential request:

   type: The response type (currently, only JSON is supported).
   properties: A list of response_field: { type, match } pairs. These match fields from the data provider response to the credential request.
   

How to run:

1. Run docker-compose file:

   docker-compose up -d

License

refresh-service is part of the 0xPolygonID project copyright 2024 ZKID Labs AG

This project is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.