This is the interface for public key cryptosystems, and various
    utility functions related to public keys and private keys.  This
    interface also defines the actual PKCS objects, public keys and
    private keys.  The interface is generic PKCS interface, which has
    capability of supporting any kind of public key algorithm.  This
    interface also implements the SILC Public Key and routines for
    encoding and decoding SILC Public Key (as defined by the SILC
    protocol specification).  Interface or encrypting, decrypting,
    producing digital signatures and verifying digital signatures are
    also defined in this header.