MedBackend Role-Based Access Control System

FHIR-Compliant Authorization Framework with Multi-Tenant Support

B2C Healthcare Model: Single Organization Architecture

(Direct Patient Care Platforms)

Structural Components

Resource Relationships

1. Central Organization

   • Single Organization resource acts as data controller
   • Example Identifier: Organization/med-org-001
   • FHIR Profile: US Core Organization

2. Patient Resources

   • Contain mandatory reference to central org:

     "managingOrganization": {
       "reference": "Organization/med-org-001"
     }
   • Validation: Patient compartment restricts access to self-owned data

3. Care Team Structure

   • Practitioners require active PractitionerRole with:

     "organization": {
       "reference": "Organization/med-org-001"
     }

Access Validation Flow

Recommended Use Cases

• Direct-to-consumer telehealth platforms
• Single-clinic EHR systems
• Mobile health applications with centralized care teams

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B2B2C Healthcare Model: Multi-Tenant Architecture

(Enterprise Health Platforms)

Structural Hierarchy

Role Coding System

Based on SNOMED CT codes:

Role Code	SNOMED CT Reference	Access Privileges
ict	110462001	User management, System configuration
doctor	158965000	Clinical data access, Patient records

Role Assignment Example

{
  "resourceType": "PractitionerRole",
  "code": [
    {
      "coding": [
        {
          "system": "http://snomed.info/sct",
          "code": "158965000",
          "display": "Medical practitioner"
        }
      ]
    }
  ]
}

Inheritance Configuration

{
  "validators": {
    "legitimate_interest": {
      "role_inheritance_levels": 1,
      "cross_organization_access": false
    }
  }
}

Inheritance Behavior

• Practitioners inherit privileges from parent organizations
• Maximum inheritance depth configurable (default=1)
• Example:
  Hospital → Cardiology Department (1-level inheritance)

---

Custom Organization Compartment

Extended FHIR Access Control Mechanism

Implementation Details

Compartment Definition

{
  "extension": [
    {
      "url": "https://medbackend.com/fhir/Extensions/organization-compartment",
      "valueReference": {
        "reference": "Organization/tenant-org-002"
      }
    }
  ]
}

Use Case Example - Shared Library Resource

{
  "resourceType": "Library",
  "extension": [
    {
      "url": "https://medbackend.com/fhir/Extensions/organization-compartment",
      "valueReference": {
        "reference": "Organization/research-org-005"
      }
    }
  ],
  "status": "active",
  "type": {
    "coding": [
      {
        "system": "http://terminology.hl7.org/CodeSystem/library-type",
        "code": "logic-library"
      }
    ]
  }
}

Access Control Matrix

Resource Type	Default Compartment	Organization Compartment Required
Patient	Patient	No
Practitioner	Practitioner	Yes (for multi-tenant)
Library	N/A	Yes
Device	Device	Yes

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Security Best Practices

1. Role Assignment Rules

   • Never assign doctor role at RootOrganization level
   • Minimum privilege principle for ict roles
   • Regular role audits via FHIR's Provenance resource

2. Compartment Management

   • Auto-tag resources during creation via Azure Functions
   • Implement compartment validation middleware:

     def validate_compartment(resource, organization):
         if resource.meta.security != organization.compartment_tag:
             raise AccessDeniedError("Invalid compartment access")

3. Audit Logging

   {
     "resourceType": "AuditEvent",
     "type": {
       "system": "http://terminology.hl7.org/CodeSystem/audit-event-type",
       "code": "rest"
     },
     "action": "E",
     "outcome": "0",
     "recorded": "2023-07-15T12:34:56Z",
     "agent": [
       {
         "type": {
           "coding": [
             {
               "system": "http://terminology.hl7.org/CodeSystem/extra-security-role-type",
               "code": "ict"
             }
           ]
         }
       }
     ]
   }

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Implementation References

1. FHIR Compartments: HL7 Compartment Definition
2. SNOMED CT Roles: SNOMED Practitioner Roles
3. Azure RBAC Patterns: Azure API Management Security