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Attributes in SURFconext

When a user logs in to a service provider, SURFconext sends a so-called SAML assertion to the service provider. This SAML assertion contains a number of statements about the user who is logging in to you service, including his identity, and possibly a number of additional attributes (see below).

User identifiers

The user's identity is transmitted in the form of the NameID element of the SAML statement. Every Identity Provider must supply a NameID, but for privacy reasons SURFconext will generate a new one regardless. For convenience, this identifier is duplicated in the SAML attribute eduPersonTargetedID (see below).

Service Providers should use the NameID or eduPersonTargetedID (rather than email address, or other attributes that might change over time) to identify users. The NameId is guaranteed to be stable and never change for a fixed user (except in the case of transient identifiers, see below). It is generated for each new user by SURFconext and is based on a hash over the uid, schacHomeorganization (together a unique user accross the federation), the SP entityID and a secret. It is therefore both unique for that user and specific to the SP, so SP's cannot correlate their received NameID's between eachother.

SURFconext can provide NameIDs of 2 different types:

  • A persistent identifier. A persistent NameID contains a random string that uniquely identifies the user for this SP, and which persists over multiple sessions for the same user.
  • A transient identifier. A transient NameID contain a random string that uniquely identifies the user for this SP during the session. Once the user's session at SURFconext expires and the users logs into your service once more, a new transient identifier will be generated for the user and SP.

Persistent and transient identifiers typically have the form 'bd09168cf0c2e675b2def0ade6f50b7d4bb4aaef'. However, please do not rely on the identifier being a hexadecimal string, as the syntax may change in the future.

The two supported NameID types, for respectively persistent and transient NameID specifiers, are:

  • urn:oasis:names:tc:SAML:2.0:nameid-format:persistent
  • urn:oasis:names:tc:SAML:2.0:nameid-format:transient


Attribute schemas

SURFconext supports two attributes schemas: a (SAML2.0 compliant) urn:oid schema and a (SAML1.1) named urn schema. Both of these can be used to convey the same information (except for the NameID, which is only available in the urn:oid schema). By default SURFconext will provide attributes in both schemata as part of the assertion. It is not recommended to mix the use of these schemata, but for legacy reason SURFconext offers both.

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