OpenSC provides a set of libraries and utilities to access smart cards. Its main focus is on cards that support cryptographic operations. It facilitates their use in security applications such as mail encryption, authentication, and digital signature. OpenSC implements the PKCS#11 API so applications supporting this API, such as Mozilla Firefox and Thunderbird, can use it. OpenSC implements the PKCS#15 standard and aims to be compatible with every software that does so, too.