The OpenSAML V2 software has reached its End of Life and is no longer supported. This documentation is available for historical purposes only.


Trust Engines

Trust engines are used to validate and establish trust of untrusted tokens, such as Credential and Signature instances. They will typically be based on resolving trust material from a trusted information resolver of some kind.

Using Trust Engines

Trust Engines must implement the interface. Particular implementations, some of which are described in the next section, may require some information at construction time, but once you have constructed an instance, the usage will be as described here.  A given trust engine implementation will be parameterized with the type of token it processes, such as a Credential or Signature.

The main trust engine interface method is validate(TokenType token, CriteriaSet trustBasisCriteria), which has a boolean return type.  If true, the token was valid and trusted; if false, it was either invalid or could not be established as trusted.  An exception is thrown if there is a problem evaluating the token.

The parameter specifies the criteria for validating the token and establishing trust. This criteria set will contain one or more instances of The mandatory and optional types of criteria which can be supplied in the set are specific to a particular trust engine implementation. In turn, these are therefore often typically directly related to (and often in fact wholly defined by) the requirements of an underlying trusted information resolver, such as and

Typical examples of Criteria include:

  • - the entity which owns or generated the token that is being processed
  • - the usage specifier for a trusted credential
  • - the SAML 2 metadata role and protocol associated with an entity whose token is being processed.

Other typical criteria may be found in package

Verifying Credentials


Verifying XML Signatures