RSA Security Inc. PKCS #11 Cryptographic Token Interface (Cryptoki)
2.20 header files.

This standard specifies an API, called Cryptoki, to devices which hold
cryptographic information and perform cryptographic functions. Cryptoki,
pronounced crypto-key and short for cryptographic token interface,
follows a simple object-based approach, addressing the goals of
technology independence (any kind of device) and resource sharing
(multiple applications accessing multiple devices), presenting to
applications a common, logical view of the device called a cryptographic
token.