libpkcs11-helper is a library that simplifies the interaction with PKCS#11
 providers for end-user applications.
 .
 libpkcs11-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.
 .
 libpkcs11-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.