Identity Provider
A central service that manages digital identities, performs authentication, and supplies user attributes to applications and APIs.
Classification
- ComplexityHigh
- Impact areaTechnical
- Decision typeArchitectural
- Organizational maturityIntermediate
Technical context
Principles & goals
Use cases & scenarios
Compromises
- Compromised IdP instance grants broad system access
- Misconfiguration of claims leads to overprivilege
- Incompatible standards between partners prevent federation
- Use standardized protocols and vetted libraries
- Implement MFA and short-lived tokens
- Operate IdP redundantly and monitor availability and latency
I/O & resources
- User directory (LDAP/AD) or identity data source
- Application/service provider configuration
- Policies for authentication, MFA and token lifetime
- Auth tokens (OIDC JWTs, SAML assertions)
- Audit and login logs
- Attribute sets for connected services
Description
An Identity Provider (IdP) is a service that centrally manages digital identities and provides authentication and attributes to applications. It supports single sign-on, federated identity and centralized access control using standards such as SAML and OpenID Connect. It is key to secure, scalable access architectures.
✔Benefits
- Reduced password management and improved user experience via SSO
- Consistent access control and auditability
- Enables federation and partner integration
✖Limitations
- Single point of failure without redundancy and high availability
- Complexity supporting legacy apps without standards
- Administrative effort for user and attribute mapping
Trade-offs
Metrics
- Number of successful SSO logins
Measures successful authentications via the IdP per time unit.
- Mean time to recover (MTTR) IdP
Time to restore the IdP service after an outage.
- Token issuance latency
Average duration from auth request to token issuance.
Examples & implementations
Keycloak as central IdP
Open‑source IdP for SSO and federation used to consolidate internal applications.
Azure AD for SaaS integration
Microsoft cloud IdP for user management, SSO and B2B federation with external partners.
OIDC provider for API authentication
Use of an OIDC provider to issue access tokens for machine clients and APIs.
Implementation steps
Requirements analysis (protocols, MFA, SLA)
Select or provision the IdP (cloud or on‑premise)
Integration, testing, monitoring and phased rollout
⚠️ Technical debt & bottlenecks
Technical debt
- Temporary custom claims instead of a long-term attribute strategy
- Legacy adapters for old apps without standard protocols
- Missing automation for provisioning and certificate rotation
Known bottlenecks
Misuse examples
- Using IdP as an authorization solution without fine-grained policies
- Public exposure of IdP admin interface without access control
- Relying on deprecated protocols without security updates
Typical traps
- Incomplete attribute mapping leads to missing permissions
- Untested partner integration breaks product scenarios
- Insufficient token revocation on compromise
Required skills
Architectural drivers
Constraints
- • Regulatory requirements (e.g., GDPR)
- • Legacy applications without standard protocols
- • Network latency and geographic distribution