The GSS-API is defined in a language independent way in RFC 2743. The Java language bindings are defined in RFC 2853
An application starts out by instantiating a
which then serves as a factory for a security context. An application
can use specific principal names and credentials that are also created
using the GSSManager; or it can instantiate a
context with system defaults. It then goes through a context
establishment loop. Once a context is established with the
peer, authentication is complete. Data protection such as integrity
and confidentiality can then be obtained from this context.
The GSS-API does not perform any communication with the peer. It merely produces tokens that the application must somehow transport to the other end.
Credential AcquisitionThe GSS-API itself does not dictate how an underlying mechanism obtains the credentials that are needed for authentication. It is assumed that prior to calling the GSS-API, these credentials are obtained and stored in a location that the mechanism provider is aware of. However, the default model in the Java platform will be that mechanism providers must obtain credentials only from the private or public credential sets associated with the
Subjectin the current access control context. The Kerberos v5 mechanism will search for the required INITIATE and ACCEPT credentials (
KerberosKey) in the private credential set where as some other mechanism might look in the public set or in both. If the desired credential is not present in the appropriate sets of the current Subject, the GSS-API call must fail.
This model has the advantage that credential management is simple and predictable from the applications point of view. An application, given the right permissions, can purge the credentials in the Subject or renew them using standard Java API's. If it purged the credentials, it would be sure that the JGSS mechanism would fail, or if it renewed a time based credential it would be sure that a JGSS mechanism would succeed.
This model does require that a
JAAS login be performed in order to
authenticate and populate a Subject that the JGSS mechanism can later
utilize. However, applications have the ability to relax this
restriction by means of a system property:
javax.security.auth.useSubjectCredsOnly. By default
this system property will be assumed to be
true (even when
it is unset) indicating that providers must only use the credentials
that are present in the current Subject. However, if this property is
explicitly set to false by the application, then it indicates that
the provider is free to use any credentials cache of its choice. Such
a credential cache might be a disk cache, an in-memory cache, or even
just the current Subject itself.
Related DocumentationFor an online tutorial on using Java GSS-API, please see Introduction to JAAS and Java GSS-API.
Interface Summary Interface Description GSSContextThis interface encapsulates the GSS-API security context and provides the security services that are available over the context. GSSCredentialThis interface encapsulates the GSS-API credentials for an entity. GSSNameThis interface encapsulates a single GSS-API principal entity.
Class Summary Class Description ChannelBindingThis class encapsulates the concept of caller-provided channel binding information. GSSManagerThis class serves as a factory for other important GSS-API classes and also provides information about the mechanisms that are supported. MessagePropThis is a utility class used within the per-message GSSContext methods to convey per-message properties. OidThis class represents Universal Object Identifiers (Oids) and their associated operations.
Exception Summary Exception Description GSSExceptionThis exception is thrown whenever a GSS-API error occurs, including any mechanism specific error.