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The importance of a secure, automated metadata refresh process can not be over-emphasized. All participants are strongly encouraged to configure their software to refresh and verify metadata at least daily. An optimal process will attempt to refresh metadata every hour and will intelligently short-circuit that attempt if the metadata file has not changed on the server. This The latter is done accomplished using a technique called HTTP Conditional GET.
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A secure web server typically protects its browser-facing resources with TLS. To obtain a trusted TLS certificate, an administrator issues a Certificate Signing Request (CSR) to a trusted CA. In doing so, a private TLS key is generated. This key must be generated securely and kept safe for the entirety of its lifetimeentire lifetime of the server. See: TLS Server Certificates
A SAML IdP is a secure web server that issues SAML assertions to SPs upon request. Assertions are signed by the IdP for authenticity and integrity. The IdP administrator generates a private signing key for this purpose. (The corresponding public key is published in SAML metadata.) Like the TLS key, the signing key must be generated securely and kept safe indefinitely. A compromised IdP signing key is the absolute worst thing that can happen in a federated context. See: IdP Key Handling
Develop a strategy for securing your private keys before you generate them. Avoid moving them around by generating the keys on the IdP in the first place. Strictly control access to the IdP system on which the keys are stored. Keep the IdP software and the underlying operating system software patched and up to date.
Use of Primary Domain
An organization's primary domain is a critical piece of information used repeatedly in metadata.
Entity ID
The entityID is an identifier for your IdP. Although it is almost always a URL, an entityID is a name (not a location). One of your first (and perhaps most important) tasks is to choose an a permanent entityID in a namespace you own. Thus the host part of the chosen URL must be rooted in a DNS name you own (as indicated in the whois database). Almost This is almost always this is the primary domain of your organization.
Example. Suppose your primary domain is example.edu. In this case, your IdP entityID might be: https://sso.example.edu/idp where the primary domain is example.edu
Choose your entityID carefully—you may not get a second chance. Once an entityID is released into the wild, it will be difficult to change, at least not without a lot of pain.
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A Scope is a suffix appended to so-called scoped attributes (such as eduPersonPrincipalName) that . The attribute's Scope indicates the asserting IdP, which is why the best Scope value is the primary domain of the organization.. Since these scoped attributes are typically used for access control at the SP, they are likewise difficult to change once released into the wild. That's why the best Scope value is the primary domain of the organization. If that changes…well, let's hope that doesn't happen.
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Avoid multiple Scopes in metadata. |
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Each of the SAML endpoints published in metadata has a location. Some of these endpoints are browser-facing, so there are branding issues to consider. Choose and so you should choose a logical hostname that makes sense to the user. This hostname need not agree with your entityID (which is a name, not a location) but in any case, the chosen hostname should be rooted in your primary domain for security, usability, and stability.
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