scd:piv: Implement import of private keys for Yubikeys.
* scd/app-piv.c (concat_tlv_list): Add arg 'secure' and adjust callers. (writekey_rsa, writekey_ecc): New. (do_writekey): New. (do_writecert): Provide a better error message for an empty cert. (app_select_piv): Register do_writekey. * scd/iso7816.c (iso7816_send_apdu): New. * scd/app-common.h (APP_WRITEKEY_FLAG_FORCE): New. * agent/command.c (cmd_keytocard): Make the timestamp optional. * tools/card-call-scd.c (inq_writekey_parms): Remove. (scd_writekey): Rewrite. * tools/gpg-card.c (cmd_writekey): New. (enum cmdids): Add cmdWRITEKEY. (dispatch_command, interactive_loop): Call cmd_writekey.
This has been tested with gpgsm and RSA keys. For ECC keys only
partly tested using the sample OpenPGP nistp256 and nistp384 keys
because gpgsm does not yet support ECC certificates and thus we can't
write the certificates to the cert object after a writekey. Note that
they nevertheless show up in "gpgcard list" because gpg-card searches
for them in gpg and gpgsm. However, this does not work completely.
- Signed-off-by: Werner Koch <wk@gnupg.org>