Allow generation of card keys up to 4096 bit.

This patch implementes a chunk mode to pass the key parameters from
scdaemon to gpg.  This allows to pass arbitrary long key paremeters;
it is used for keys larger than 3072 bit.

Note: the card key generation in gpg is currently broken.  The keys
are generated but it is not possible to create the self-signature
because at that time the gpg-agent does not yet know about the new
keys and thus can't divert the sign request to the card.  We either
need to run the learn command right after calling agent_scd_genkey or
implement a way to sign using the currently inserted card.  Another
option would be to get rid of agent_scd_genkey and implement the
feature directly in agent_genkey.

1 files changed, 6 insertions, 2 deletions

diff --git a/scd/command.c b/scd/command.c
index be11ccb77..a579b24eb 100644
--- a/scd/command.c
+++ b/scd/command.c
@@ -1288,11 +1288,15 @@ static const char hlp_genkey[] =
   "\n"
   "Generate a key on-card identified by NO, which is application\n"
   "specific.  Return values are application specific.  For OpenPGP\n"
-  "cards 2 status lines are returned:\n"
+  "cards 3 status lines are returned:\n"
   "\n"
   "  S KEY-FPR  <hexstring>\n"
   "  S KEY-CREATED-AT <seconds_since_epoch>\n"
-  "  S KEY-DATA [p|n] <hexdata>\n"
+  "  S KEY-DATA [-|p|n] <hexdata>\n"
+  "\n"
+  "  'p' and 'n' are the names of the RSA parameters; '-' is used to\n"
+  "  indicate that HEXDATA is the first chunk of a parameter given\n"
+  "  by the next KEY-DATA.\n"
   "\n"
   "--force is required to overwrite an already existing key.  The\n"
   "KEY-CREATED-AT is required for further processing because it is\n"