Identity Provider (IdP) vs Service Provider (SP)
This is an informative guide on the differences between an identity provider (IdP) and a service provider (SP), as it pertains to Descope.
Identity Provider (IdP)
An Identity Provider (IdP) system creates, maintains, and manages identity information for principals and provides authentication services to relying applications within a federation or distributed network. It is responsible for verifying the identity of users and issuing authentication tokens or credentials.
Service Provider (SP)
A Service Provider (SP) is an entity that provides web-based applications, services, or resources to users after successful authentication from an IdP. The SP relies on the IdP to authenticate users and may grant or deny access to its services based on that authentication.
What is SAML
Security Assertion Markup Language (SAML) is an XML-based standard for exchanging authentication and authorization data between parties. In a typical SAML flow, a user tries to access a service (often called a "Service Provider" or SP). If the user isn't authenticated, they are redirected to an Identity Provider (IdP), where they authenticate. Upon successful authentication, the IdP returns a SAML assertion to the SP. This assertion contains statements (or assertions) about the user, such as their name, roles, and other attributes. The SP then uses this assertion to grant access to the user. This process enables Single Sign-On (SSO), allowing users to authenticate once with the IdP and gain access to multiple services without being prompted to log in again.
What is OIDC
OpenID Connect (OIDC) is a protocol that sits on top of the OAuth 2.0 protocol, designed to authenticate users. While OAuth 2.0 is primarily about authorization (delegating access to resources without sharing credentials), OIDC extends this with identity features, enabling clients to verify the end-users identity based on the authentication performed by an authorization server. OIDC uses JSON Web Tokens (JWT) to represent the identity information. In the context of OIDC, the term "Federated Identity Providers" often comes up. Federated identity refers to linking a person's electronic identity and attributes stored across multiple identity management systems. This means a user can use a single set of credentials to authenticate across multiple domains or services.
SAML vs OIDC
The most prominent differences between SAML and OIDC are their formats and the use cases they typically address. SAML uses XML for its assertions, while OIDC uses JSON Web Tokens (JWT). Additionally, SAML has been around longer and is often associated with enterprise Single Sign-On in web applications. In contrast, OIDC is a newer protocol commonly used for authenticating users in modern web, mobile, and API applications, building upon the OAuth 2.0 framework. Another key difference is in their focus: SAML encompasses authentication and authorization, while OIDC is primarily for authentication on top of the OAuth 2.0 authorization framework.