There's currently a small problem in scard-opensc.c if there's more than one
private key object for a given certificate (i.e. public key). For example some
cards OSs do not support signing and decryption with one private key object
=> if you want to use the same key for signing and decryption you need
two copies of the key (one for signing and one for decryption).
Currently scard-opensc.c uses the sc_pkcs15_find_prkey_by_id function to get
the private key object (specified by the pkcs15 id) but this function returns
only the first private key object found. It would be better to use the
sc_pkcs15_find_prkey_by_id_usage function and search for a private key
with the desired capability (see attached patch).

Nils