* agent/agent.h (agent_card_ecc_kem): New.
* agent/divert-scd.c (agent_card_ecc_kem): New.
* agent/pkdecrypt.c (ecc_extract_pk_from_key): New.
(ecc_extract_sk_from_key): New.
(ecc_raw_kem, get_cardkey, ecc_get_curve): New.
(ecc_pgp_kem_decrypt): Support a key on smartcard for ECC.
(composite_pgp_kem_decrypt): Handle a case of a key on smartcard.
* common/sexputil.c (get_ecc_curve_from_key): New.
* common/util.h (get_ecc_curve_from_key): New.