AWS IAM Identity Center Architecture

The Sovereign Gateway for the Fleet

AWS IAM Identity Center (formerly AWS SSO) is the “Sovereign Gateway” for the modern cloud enterprise. It is the evolution of IAM Users, designed to provide a centralized hub for managing workforce access across hundreds or thousands of AWS accounts. By federating with your primary identity provider (like Okta or Entra ID), Identity Center allows you to assign “Permission Sets” to users and groups once and propagate them across your entire AWS Organization. For the IAM architect, Identity Center is the engine of Enterprise Scale, enabling seamless single sign-on while maintaining a rigid, policy-driven security posture for every account in the fleet.

IDENTITY CENTER

Enterprise Sovereign

Core Mission

Multi-Account Orchestration. Establishing a centralized workforce identity hub that decouples user management from individual AWS accounts, automating access lifecycle through SCIM and protocol-driven SSO.

Like a Universal Skeleton Key: Imagine a city full of apartment buildings (Your AWS Accounts). In the old days, every resident had to carry a different key for every building (Local IAM Users). Now, you have a "Sovereign Key Center." Residents use their State ID (Your Home IdP) to prove who they are, and the Center issues them a single "Universal Skeleton Key" (Identity Center SSO). This key only opens the specific doors in the specific buildings they are authorized to enter, and the Center can deactivate it for the whole city in one click.

AWS Organization Governance / Enterprise SSO Launch / Automated SCIM Provisioning / Developer Productivity

The Multi-Account Governance Matrix

Designing for Identity Center requires aligning your organizational structure with Permission Sets.

Strategic Identity Components

Component	Strategic Responsibility	IAM Implementation
Permission Sets	Reusable Blueprint.	Defines the IAM policies that will be deployed into target accounts.
Account Assignments	The Authorization Mapping.	Links Users/Groups to a Permission Set within a specific AWS account.
SCIM Provisioning	Automated Sync.	Automatically creates and updates user shadow-objects from your external IdP.
SAML IdP Integration	Trusted Federation.	The OIDC/SAML handshake that establishes the bridge between Okta/Entra and AWS.

The Centralized Workforce Flow

Identity Center simplifies the user experience while hardening the security handshake.

graph LR
    Login[Login via IdP] --> Portal[Access Portal]
    Portal --> Select[Select Account]
    Select --> Access[Authorized Session]

1

Federated Authentication (The Bridge)

The journey begins at your company's primary IdP. The user authenticates using their corporate credentials and MFA. A SAML assertion is sent to the AWS Identity Center "Sovereign Bridge," which validates the trust relationship and recognizes the user.

2

The Sovereign Access Portal

The user is presented with the **AWS access portal**—a personalized dashboard showing every AWS account and role they are authorized to access. This portal acts as the central clearinghouse for cross-account navigation, eliminating the need for complex account-switching URLs.

3

Ephemeral Session Issuance

When the user selects an account, Identity Center calls STS to issue **Temporary Security Credentials** based on the assigned "Permission Set." This ephemeral session exists only for the duration of the work, ensuring that no persistent credentials ever leak or remain static.

---

Technical Identity Implementation

Permission Sets can be defined as code using Terraform or CloudFormation.

Permission Set Design (Terraform Example)

# Defining a 'Predefined' ViewOnly Permission Set
resource "aws_ssoadmin_permission_set" "read_only" {
  name             = "Sovereign-ReadOnly"
  instance_arn     = local.sso_instance_arn
  managed_policy_arn = "arn:aws:iam::aws:policy/ReadOnlyAccess"
  session_duration = "PT4H" # 4-hour limit
}

# Assigning the Set to a Group in a specific Account
resource "aws_ssoadmin_account_assignment" "dev_team" {
  instance_arn       = local.sso_instance_arn
  target_id          = "123456789012" # Dev Account ID
  target_type        = "AWS_ACCOUNT"
  principal_id       = okta_group.developers.id
  principal_type     = "GROUP"
  permission_set_arn = aws_ssoadmin_permission_set.read_only.arn
}

Identity Center Implementation Guides

Master the technical ceremonies of multi-account SSO and SCIM-driven governance.

Permission Design

Creating custom "Customer Managed Policies" to use within your Identity Center permission sets.

MFA Enforcement

Ensuring your external IdP mandates phishing-resistant MFA before granting access to the AWS portal.

SCIM Federation

Setting up the automatic synchronization of users from Okta to AWS Identity Center.

Org Integration

Aligning Identity Center with AWS Organizations to automate access for new accounts.

Next Steps

• Explore AWS Identity Center Setup Guide for deep dive docs.
• Review Attribute-Based Access Control (ABAC) for scaling permissions via tags.
• Check Access History to monitor cross-account sign-in events.