[RFC 4/4] g10: add ability to transfer a private key to the tpm

[James Bottomley]

Exactly like the gpg --edit-key command keytosc, keytotpm has been
added which immedately converts the private key file to TPM shadowed
form.  Once this is done, the key cannot be recovered and may only be
used via the TPM of the computer system on which the conversion was
done.  If that system is ever lost, or its TPM cleared, the shadowed
key becomes unusable.

Signed-off-by: James Bottomley <James.Bottomley at HansenPartnership.com>
---
 g10/call-agent.c | 22 ++++++++++++++++++++++
 g10/call-agent.h |  3 +++
 g10/keyedit.c    | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/g10/call-agent.c b/g10/call-agent.c
index 61d06c663..356ec8539 100644
--- a/g10/call-agent.c
+++ b/g10/call-agent.c
@@ -759,6 +759,28 @@ agent_scd_apdu (const char *hexapdu, unsigned int *r_sw)
   return err;
 }
 
+int
+agent_keytotpm (ctrl_t ctrl, const char *hexgrip)
+{
+  int rc;
+  char line[ASSUAN_LINELENGTH];
+  struct default_inq_parm_s parm;
+
+  snprintf(line, DIM(line), "KEYTOTPM %s\n", hexgrip);
+
+  rc = start_agent (ctrl, 0);
+  if (rc)
+    return rc;
+  parm.ctx = agent_ctx;
+  parm.ctrl = ctrl;
+
+  rc = assuan_transact (agent_ctx, line, NULL, NULL, default_inq_cb, &parm,
+			NULL, NULL);
+  if (rc)
+    log_log (GPGRT_LOGLVL_ERROR, _("error from TPM: %s\n"), gpg_strerror (rc));
+  return rc;
+}
+
 
 int
 agent_keytocard (const char *hexgrip, int keyno, int force,
diff --git a/g10/call-agent.h b/g10/call-agent.h
index f45b64d90..85c939fa0 100644
--- a/g10/call-agent.h
+++ b/g10/call-agent.h
@@ -88,6 +88,9 @@ gpg_error_t agent_scd_apdu (const char *hexapdu, unsigned int *r_sw);
 /* Update INFO with the attribute NAME. */
 int agent_scd_getattr (const char *name, struct agent_card_info_s *info);
 
+/* send the KEYTOTPM command */
+int agent_keytotpm (ctrl_t ctrl, const char *hexgrip);
+
 /* Send the KEYTOCARD command. */
 int agent_keytocard (const char *hexgrip, int keyno, int force,
                      const char *serialno, const char *timestamp);
diff --git a/g10/keyedit.c b/g10/keyedit.c
index 81344eb79..fd82f2d21 100644
--- a/g10/keyedit.c
+++ b/g10/keyedit.c
@@ -1241,7 +1241,7 @@ enum cmdids
 #endif /*!NO_TRUST_MODELS*/
   cmdSHOWPREF,
   cmdSETPREF, cmdPREFKS, cmdNOTATION, cmdINVCMD, cmdSHOWPHOTO, cmdUPDTRUST,
-  cmdCHKTRUST, cmdADDCARDKEY, cmdKEYTOCARD, cmdBKUPTOCARD,
+  cmdCHKTRUST, cmdADDCARDKEY, cmdKEYTOCARD, cmdKEYTOTPM, cmdBKUPTOCARD,
   cmdCLEAN, cmdMINIMIZE, cmdGRIP, cmdNOP
 };
 
@@ -1292,6 +1292,8 @@ static struct
     N_("add a key to a smartcard")},
   { "keytocard", cmdKEYTOCARD, KEYEDIT_NEED_SK | KEYEDIT_NEED_SUBSK,
     N_("move a key to a smartcard")},
+  { "keytotpm", cmdKEYTOTPM, KEYEDIT_NEED_SK | KEYEDIT_NEED_SUBSK,
+    N_("convert a key to TPM form using the local TPM")},
   { "bkuptocard", cmdBKUPTOCARD, KEYEDIT_NEED_SK | KEYEDIT_NEED_SUBSK,
     N_("move a backup key to a smartcard")},
 #endif /*ENABLE_CARD_SUPPORT */
@@ -1789,6 +1791,47 @@ keyedit_menu (ctrl_t ctrl, const char *username, strlist_t locusr,
 	    }
 	  break;
 
+	case cmdKEYTOTPM:
+	  /* FIXME need to store the key and not commit until later */
+	  {
+	    KBNODE node = NULL;
+	    switch (count_selected_keys (keyblock))
+	      {
+	      case 0:
+		if (cpr_get_answer_is_yes
+                    ("keyedit.keytocard.use_primary",
+                     /* TRANSLATORS: Please take care: This is about
+                        moving the key and not about removing it.  */
+                     _("Really move the primary key? (y/N) ")))
+		  node = keyblock;
+		break;
+	      case 1:
+		for (node = keyblock; node; node = node->next)
+		  {
+		    if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY
+			&& node->flag & NODFLG_SELKEY)
+		      break;
+		  }
+		break;
+	      default:
+		tty_printf (_("You must select exactly one key.\n"));
+		break;
+	      }
+	    if (node)
+	      {
+		PKT_public_key *xxpk = node->pkt->pkt.public_key;
+		char *hexgrip;
+
+		hexkeygrip_from_pk (xxpk, &hexgrip);
+		if (!agent_keytotpm (ctrl, hexgrip))
+		  {
+		    redisplay = 1;
+		  }
+		xfree (hexgrip);
+	      }
+	  }
+	  break;
+
 	case cmdKEYTOCARD:
 	  {
 	    KBNODE node = NULL;
-- 
2.12.3