Shibboleth (software)

Shibboleth is a standards-based, open-source software package for web single sign-on (SSO) across or within organizational boundaries. It allows sites to make informed authorization decisions for individual access to protected online resources in a privacy-preserving manner. The system enables the secure exchange of attributes between identity providers (IdPs) and service providers (SPs).

Shibboleth implements widely used federated identity standards, primarily the Security Assertion Markup Language (SAML). These standards facilitate the transfer of authentication and attribute information between organizations, enabling users to access resources using their existing organizational credentials, without needing separate logins for each service.

The core components of Shibboleth are:

• Identity Provider (IdP): The system responsible for authenticating users and releasing attribute information. The IdP typically resides within the user's home organization and verifies their credentials against its internal authentication mechanisms (e.g., username/password, multi-factor authentication).

• Service Provider (SP): The system that controls access to the protected resource. The SP relies on the IdP to authenticate the user and provide attributes necessary for authorization. It intercepts user requests, initiates the authentication process if needed, and makes access decisions based on the received attributes.

• Metadata: XML documents that describe the configuration and capabilities of IdPs and SPs. Metadata is exchanged between parties to establish trust and facilitate communication. This metadata includes information such as the entity ID, supported protocols, public keys for encryption and signing, and contact information.

Shibboleth's strength lies in its support for attribute-based access control (ABAC). The IdP releases attributes about the user (e.g., affiliation, group membership, email address) to the SP, which then uses these attributes to determine whether to grant access. This allows for fine-grained access control policies based on user characteristics rather than just simple authentication.

Key features of Shibboleth include:

• Federated Identity Management: Enables seamless access to resources across different organizations.
• Single Sign-On (SSO): Users authenticate only once at their home organization and can then access multiple services without re-authenticating.
• Attribute-Based Access Control (ABAC): Enables fine-grained access control based on user attributes.
• Privacy Protection: Attributes released to SPs can be controlled, limiting the amount of personal information shared.
• Open Standards: Based on widely adopted standards like SAML.
• Extensibility: The software is designed to be extensible, allowing for customization and integration with existing systems.

Shibboleth is commonly used in higher education, research, and government organizations to provide secure access to online resources while simplifying user management and protecting user privacy.