Session handles and object handles

A session handle is a Cryptoki-assigned value that identifies a session. It is in many ways akin to a file handle, and is specified to functions to indicate which session the function should act on. All threads of an application have equal access to all session handles. That is, anything that can be accomplished with a given file handle by one thread can also be accomplished with that file handle by any other thread of the same application.

Cryptoki also has object handles, which are identifiers used to manipulate Cryptoki objects. Object handles are similar to session handles in the sense that visibility of a given object through an object handle is the same among all threads of a given application. R/O sessions, of course, only have read-only access to token objects, whereas R/W sessions have read/write access to token objects.

Valid session handles and object handles in Cryptoki always have nonzero values. For developers' convenience, Cryptoki defines the following symbolic value:

#define CK_INVALID_HANDLE 0

RSA Security Inc. Public-Key Cryptography Standards - PKCS#11 - v210