PKCS#11 is RSA Security published standard. PKCS#11 is the de-facto standard to access cryptographic devices.
pkcs11-helper is a library that simplifies the interaction with PKCS#11 providers for end-user applications.
Features
pkcs11-helper allows using multiple PKCS#11 providers at the same time, enumerating available token certificates, or selecting a certificate directly by serialized id, handling card removal and card insert events, handling card re-insert to a different slot, supporting session expiration and much more all using a simple API.
pkcs11-helper is not designed to manage card content, since object attributes are usually vendor specific, and 99% of application need to access existing objects in order to perform signature and decryption.
Compatibility
The pkcs11-helper library is available in POSIX and WIN32 compliant systems.
The pkcs11-helper library should work with almost any PKCS#11 provider, since it uses the minimum required features of the PKCS#11 standard.
Support
pkcs11-helper support is available via the OpenSC Project.