Grid Security Infrastructure

The Grid Security Infrastructure (GSI), formerly called the Globus Security Infrastructure, is a specification for secret, tamper-proof, delegatable communication between software in a grid computing environment. Secure, authenticatable communication is enabled using asymmetric encryption.
Authentication.
Authentication is performed using digital signature technology (see digital signatures for an explanation of how this works); secure authentication allows resources to lock data to only those who should have access to it. 
Delegation.
Authentication introduces a problem: often a service will have to retrieve data from a resource independent of the user; in order to do this, it must be supplied with the appropriate privileges. GSI allows for the creation of delegated privileges: a new key is created, marked as a delegated and signed by the user; it is then possible for a service to act on behalf of the user to fetch data from the resource.
Security Mechanisms.
Communications may be secured using a combination of methods: