scd: Add --challenge-response option to PK_AUTH for OpenPGP card.

* scd/app-openpgp.c (rmd160_prefix, sha1_prefix, sha224_prefix)
(sha256_prefix, sha384_prefix, sha512_prefix): Move the scope up.
(gen_challenge): New.
(do_auth): Support challenge-response check if it signs correctly.
* scd/app.c (app_auth): Remove the check INDATA and INDATALEN.
* scd/command.c (cmd_pkauth): Support --challenge-response option.

--

GnuPG-bug-id: 5862
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

scd/app.c

@@ -2053,7 +2053,7 @@ app_auth (card_t card, ctrl_t ctrl, const char *keyidstr,
 {
   gpg_error_t err;
 
-  if (!indata || !indatalen || !outdata || !outdatalen || !pincb)
+  if (!outdata || !outdatalen || !pincb)
     return gpg_error (GPG_ERR_INV_VALUE);
 
   if ((err = maybe_switch_app (ctrl, card, keyidstr)))