SAML (Security Assertion Markup Language)

Security Assertion Markup Language (SAML) is an open standard framework that plays a critical role in identity management and access control. The SAML framework ensures interoperability and consistent functionality between different systems. The primary use of SAML is to enable organizations to implement single sign-on (SSO) solutions.

As an open standard framework, SAML is a set of guidelines, protocols, and specifications that are publicly available and developed through a collaborative process. It is a part of many development libraries, making it easier for developers to integrate SAML into their applications. For example, OpenSAML, Python-SAML, and SimpleSAMLphp are development libraries that implement SAML support in Java, Python, and PHP.

Although closely related, SAML and SSO are not the same thing. Single sign-on is an authentication process that allows a user to log in once and gain access to multiple applications or services with no need to log in again for each one. SAML is the underlying framework that supports the exchange of authentication and authorization data between an identity provider (IdP) and a service provider (SP).

In short, SSO is a broad concept that simplifies and secures user access to multiple applications, while SAML is a universally standard framework used by developers to ensure compatibility between SSO and other use case implementations.

SAML includes several components that work together to support various use cases.

Principal (User): The user who needs to access a service or resource. The user interacts with the service provider and the identity provider to authenticate and gain access to the desired resource. We include the user in this list of components because it helps illustrate how the other SAML components work.

Identity provider (IdP): Authenticates the user and provides identity information to the service provider. The IdP handles authentication and assertion generation.

Service provider (SP): Provides services or resources to the user. The SP relies on the identity provider to authenticate the user and is responsible for requesting authentication and consuming assertions.

SAML assertions: XML documents issued by the IdP that contain statements about the user. There are different SAML assertions, including authentication statements, attribute statements, and authorization decision statements.

SAML protocols: Protocols that define how SAML requests and responses are communicated between entities. The main SAML protocols are authentication request protocol, artifact resolution protocol, and single logout protocol.

SAML bindings: Defines how SAML protocol messages are transported between entities. Common bindings include HTTP Redirect Binding and HTTP Post Binding.

SAML profiles: Profiles define SAML use cases, and how SAML assertions, protocols, and bindings support those use cases. Common profiles include Web Browser SSO, single logout (SLO), and attribute query. 

SAML metadata: An XML document that describes the configuration and capabilities of SAML IdP and SP. It includes entity IDs, endpoints, certificates, and information on supported protocols and bindings.

SAML enables SSO by allowing authentication and authorization data to be exchanged between an identity provider and a service provider. Here’s a step-by-step explanation of how SAML enables SSO:

User requests access: The user attempts to access a service or resource provided by the SP.

SP initiates authentication request: The SP identifies that the user needs to be authenticated and responds by generating a SAML authentication request. This is usually a URL encoded with SAML request data.

User redirected to IdP: The system redirects the user to IdP, sending along the SAML request from the previous step. This can happen via HTTP redirects, HTTP POST, or artifacts.

User authenticates with IdP: The IdP presents an authentication interface for the user to input credentials. The IdP uses these credentials, usually a username and password, to verify the user’s identity.

IdP generates SAML response: Upon successful authentication, the IdP generates a SAML response, which contains a SAML assertion. To ensure integrity and authenticity, the IdP signs the assertion and includes the user’s identity and authentication status.

User redirected back to SP: The user is redirected back to the SP via HTTP POST or other mechanisms. This redirection delivers the SAML response to the SP.

SP validates SAML response: The SP receives and verifies the SAML response and extracts the user’s identity information from the SAML assertion.

SP grants access: Based on the user’s identity information and the SAML assertion, the SP grants access to the requested service or resource. In this step, the system authenticates the user and grants access to the authorized services.

The need for a mechanism like SAML was conceptualized in the late 1990s as internet usage expanded and owners of large networks wanted to authenticate across different domains and organizations. Governments, universities, and business networks were built with or connected by multiple security domains, and users in one domain often needed to access resources in another. There were several proprietary solutions designed to address this issue, but industry experts recognized a growing need for a universal standard that would work for all systems.

In 2001, the Organization for the Advancement of Structured Information Standards (OASIS) formed a Technical Committee that would create an XML framework for this universal standard. This framework would define the exchange of authentication and authorization data between security domains. OASIS adopted SAML 1.0 in November 2002, making it the first standard way to exchange authentication and authorization data between different security domains. This version of SAML provided only basic support for this exchange. OASIS adopted SAML 1.1 in September 2003, which included enhancements and improvements in error handling, implementation, and the data exchange between domains. The changes to SAML in version 1.1 were based primarily on industry feedback.

SAML 2.0 became the standard in 2005. This version was a major improvement over earlier versions, adding or improving support for many of the features currently in use. Major additions include:

Enhanced SSO and single logout (SLO): Improved mechanisms for SSO and greater flexibility in how authentication is handled across multiple domains. The introduction of SLO allowed users to log out from all sites with a single action.

Federated identity: A system of trust that allows identities to be linked across different security domains.

Metadata support and attribute management: Introduction of metadata to describe the attributes of identity providers, service providers, and other SAML entities. Attribute management facilitates the detailed and flexible exchange of this information. 

Security improvements: Stronger cryptographic algorithms and other enhancements to protect the data being exchanged.

SAML 2.0 remains the current version, and developers have continually updated it since its release. These updates include security and interoperability enhancements, deployment improvements, and support for new use cases. OASIS periodically reviews the SAML 2.0 framework to ensure it remains relevant, secure, and effective for the community.

SAML supports enhanced productivity and efficiency in several ways, primarily through security, user experience, and operational efficiency. Here are some of the key business benefits of implementing SAML:

Single sign-on (SSO): SSO is a primary benefit of SAML, allowing users to log in once and gain access to multiple applications without repeatedly entering credentials. This improves productivity and reduces login-related delays.

Improved user experience: Fewer logins are required to switch between applications and other resources. This is a smoother and more efficient workflow and improves the user experience.

Enhanced security: SAML enhances security through its support for encrypted communications and digital signatures. This ensures that authentication data is securely transmitted and can be trusted by both the identity provider and the service provider.

Centralized authentication: By centralizing authentication with a single identity provider, organizations can enforce consistent security policies and manage user access more effectively.

Reduced password fatigue: SAML reduces the number of passwords users need to remember, leading to better password practices and reduced risk of weak passwords being used across multiple services.

Streamlined user management: User provisioning and de-provisioning become more efficient, as changes made in the central identity system apply to all connected applications. This is useful for onboarding and offboarding employees.

Cost savings: A single set of credentials and a single sign-on environment reduces the number of password and login support issues. Less tech support alongside the streamlined user management process lowers the IT administrative overhead and reduces the cost of IT support.

Regulatory compliance: SAML helps organizations meet regulatory requirements by providing robust logging and auditing capabilities. This ensures that all authentication events are recorded and can be reviewed for compliance purposes.

Scalability: SAML handles large-scale deployments, making it suitable for organizations with many users and applications. It can easily scale to meet growing business needs.

Interoperability: SAML’s wide adoption and support across different platforms and systems mean organizations can integrate with a variety of third-party applications and services, enhancing flexibility and collaboration.

Reduced IT burden: By delegating authentication to a central identity provider, IT departments can reduce the time and effort spent managing individual application logins, allowing them to focus on more strategic initiatives.

Enhanced partner collaboration: SAML facilitates secure access for external partners, enabling them to collaborate and share data without compromising the organization’s security. This can lead to stronger business relationships and improved operational efficiency.

SAML offers several benefits for businesses. It enhances security, improves user experience, reduces operational expenses, and helps meet regulatory requirements.

Companies should include the SAML framework in an enterprise-wide cybersecurity plan to help them maintain strong security controls and comply with regulatory requirements.