# Ledger uSelf Agent
uSelf Agent provides Self Sovereign Identity functionalities following the standards for managing Verifiable Credentials and Decentralised Identifiers. The main standards used :
In addition to the standards, uSelf Agent follows the recommendations of the European Blockchain Services Infrastructure (EBSI) and the eIDAS 2.0.
As mentioned above, uSelf Agent provides Self Sovereign Identity functionalities. The main functionalities can be divided on the following categories:
In order to run the uSelf Agent, it is necessary to have a running instance of Redis database. Therefore, before starting the system you need to run the following command:
docker compose upOnce the redis service is available, you can start the uSelf Agent by running the following command:
./gradlew bootJar
java -jar build/libs/uself-agent-0.0.1-SNAPSHOT.jarFinally, you can access the uSelf Agent at the following URL: http://localhost:8888.
The uSelf Agent implementation for No Authorized Issue Credential is based on the OpenID Connect for Verifiable Credentials Issue. As the end user hasn't been authenticated and authorized, the process of Issue Credential is based on the use of a QR Code to redirect the end user to the uSelf Agent. From that moment on, the end user can, using the uSelf Mobile App, scan the QR Code and accept the offer of the credential. The following diagram shows the sequence of the No Authorized Issue Credential process.
sequenceDiagram
actor eu as End User
participant mobile as uSelf Mobile App
participant fe as Service Provider (Front End)
participant be as uSelf Agent (Back End)
eu->>+fe: select issue credential
fe->>+be: (GET) http://uself-agent/issuer/initiate-crendential-offer
be-->>-fe: credential offer
fe-->>fe: generate QR Code
eu->>+mobile: Scan QR Code
mobile->>+fe: Scan QR Code
fe-->>-mobile: redirect 302
mobile->>-eu: Show Offer
eu->>+mobile: consent accept offer
mobile-->>mobile: redirect 302
mobile->>+be: (GET) http://uself-agent/auth/authorize?state=*&nonce=*
be-->>-mobile: redirect http://uself-agent/direct_post
mobile-->>mobile: redirect 302
mobile->>+be: (POST) http://uself-agent/direct_post
be-->>-mobile: code
mobile->>+be: (POST) http://uself-agent/auth/token?code=code
be-->>-mobile: access_token
mobile->>+be: (GET) http://uself-agent/issuer/credential (Bearer access_token)
be-->>-mobile: credential
mobile-->>-mobile: Store Credential
fe-->>-eu: credential issued
Where in this particular case, the authentication and authorization is done previously, therefor it is not necessary to perform it again. Thereby to assure the security of the process, the uSelf Agent implementation for PreAuthorized Issue Credential is based on the use of a PIN Code provided to the end user. The following diagram shows the sequence of the PreAuthorized Issue Credential process.
sequenceDiagram
actor eu as End User
participant mobile as uSelf Mobile App
participant fe as Service Provider (Front End)
participant be as uSelf Agent (Back End)
Note over eu,be: Authentication and Authorization (PIN CODE)
eu->>+fe: select issue credential
fe->>+be: (GET) http://uself-agent/issuer/initiate-crendential-offer
be-->>-fe: credential offer
fe-->>fe: generate QR Code
eu->>+mobile: Scan QR Code
mobile->>+fe: Scan QR Code
fe-->>-mobile: redirect 302
mobile->>-eu: Show Offer
eu->>+mobile: consent accept offer
eu->>+mobile: PIN CODE
mobile-->>-eu: successfully PIN CODE
mobile-->>mobile: redirect 302
mobile->>+be: (POST) http://uself-agent/auth/token?user_pin=*&pre_authorized_code=*
be-->>-mobile: access_token
mobile->>+be: (GET) http://uself-agent/issuer/credential (Bearer access_token)
be-->>-mobile: credential
mobile-->>-mobile: Store Credential
fe-->>-eu: credential issued
The uSelf Agent implementation for Present Verifiable Presentation is based on the OpenID Connect for Verifiable Presentations. As one of the main differences with the Issue Credential process, the Present Verifiable Presentation process is based on the use of a QR Code to redirect the end user to the uSelf Agent obtaining from an authorization request instead of using a credential offer.
sequenceDiagram
actor eu as End User
participant mobile as uSelf Mobile App
participant fe as Service Provider (Front End)
participant be as uSelf Agent (Back End)
eu->>+fe: select Present VP
fe->>+be: (GET) http://uself-agent/auth/authorize?state=*&nonce=*
be-->>-fe: auth request
fe-->>fe: generate QR Code
eu->>+mobile: Scan QR Code
mobile->>+fe: Scan QR Code
fe-->>-mobile: redirect 302
mobile->>-eu: Show Auth Info
eu->>+mobile: consent send VP
mobile-->>mobile: redirect 302
mobile->>+be: (POST) http://uself-agent/direct_post
be-->>-mobile: id_token
mobile-->>-mobile: Shows validation outcome
fe-->>-eu: Authentication successfully
Further information about the details of the implementation can be found in the uSelf Agent documentation.