Login hint specification is similar to Portal Initiated Step-up’s Passing the login hint for identity info. Below describes the difference from Portal Initiated Step-up case.
The login_hint parameter will be used to pass JWE token with “hnt” as “regspec” in a JWE protected header and encrypted payload containing Big 4, email, phone number. All identity attributes are optional and not all of them are required.
After the OIDC, this token will be provided by HSID registration flow and the prospect user does not need to directly type in the information.