agent: Allow to pass a timestamp to genkey and import.

* agent/command.c (cmd_genkey): Add option --timestamp.
(cmd_import_key): Ditto.
* agent/genkey.c (store_key): Add arg timestamp and change callers.
(agent_genkey): Ditto.
* agent/findkey.c (write_extended_private_key): Add args timestamp and
newkey to write a Created line.
(agent_write_private_key): Add arg timestamp.
(agent_write_shadow_key): Ditto.
* agent/protect-tool.c (agent_write_private_key): Ditto as dummy arg.
--

Signed-off-by: Werner Koch <[email protected]>
Backported-from-master: 0da923a1240ac78d60c92cdd8488c4e405c3243b
Signed-off-by: Werner Koch <[email protected]>

8 files changed, 138 insertions, 35 deletions

diff --git a/agent/agent.h b/agent/agent.h
index 5bec5e51d..4d981adcf 100644
--- a/agent/agent.h
+++ b/agent/agent.h
@@ -413,7 +413,8 @@ void start_command_handler_ssh (ctrl_t, gnupg_fd_t);
 gpg_error_t agent_modify_description (const char *in, const char *comment,
                                       const gcry_sexp_t key, char **result);
 int agent_write_private_key (const unsigned char *grip,
-                             const void *buffer, size_t length, int force);
+                             const void *buffer, size_t length, int force,
+                             time_t timestamp);
 gpg_error_t agent_key_from_file (ctrl_t ctrl,
                                  const char *cache_nonce,
                                  const char *desc_text,
@@ -493,7 +494,7 @@ int check_passphrase_constraints (ctrl_t ctrl, const char *pw, int no_empty,
 				  char **failed_constraint);
 gpg_error_t agent_ask_new_passphrase (ctrl_t ctrl, const char *prompt,
                                       char **r_passphrase);
-int agent_genkey (ctrl_t ctrl, const char *cache_nonce,
+int agent_genkey (ctrl_t ctrl, const char *cache_nonce, time_t timestamp,
                   const char *keyparam, size_t keyparmlen,
                   int no_protection, const char *override_passphrase,
                   int preset, membuf_t *outbuf);
diff --git a/agent/command-ssh.c b/agent/command-ssh.c
index d6729b70a..a26d60417 100644
--- a/agent/command-ssh.c
+++ b/agent/command-ssh.c
@@ -3136,8 +3136,9 @@ ssh_identity_register (ctrl_t ctrl, ssh_key_type_spec_t *spec,
   if (err)
     goto out;
 
-  /* Store this key to our key storage.  */
-  err = agent_write_private_key (key_grip_raw, buffer, buffer_n, 0);
+  /* Store this key to our key storage.  We do not store a creation
+   * timestamp because we simply do not know.  */
+  err = agent_write_private_key (key_grip_raw, buffer, buffer_n, 0, 0);
   if (err)
     goto out;
 
diff --git a/agent/command.c b/agent/command.c
index 2844a9e64..9e3483e8c 100644
--- a/agent/command.c
+++ b/agent/command.c
@@ -835,8 +835,8 @@ cmd_pkdecrypt (assuan_context_t ctx, char *line)
 
 
 static const char hlp_genkey[] =
-  "GENKEY [--no-protection] [--preset] [--inq-passwd]\n"
-  "       [--passwd-nonce=<s>] [<cache_nonce>]\n"
+  "GENKEY [--no-protection] [--preset] [--timestamp=<isodate>]\n"
+  "       [--inq-passwd] [--passwd-nonce=<s>] [<cache_nonce>]\n"
   "\n"
   "Generate a new key, store the secret part and return the public\n"
   "part.  Here is an example transaction:\n"
@@ -849,11 +849,13 @@ static const char hlp_genkey[] =
   "  S: D   (rsa (n 326487324683264) (e 10001)))\n"
   "  S: OK key created\n"
   "\n"
-  "When the --preset option is used the passphrase for the generated\n"
-  "key will be added to the cache.  When --inq-passwd is used an inquire\n"
+  "If the --preset option is used the passphrase for the generated\n"
+  "key will be added to the cache.  If --inq-passwd is used an inquire\n"
   "with the keyword NEWPASSWD is used to request the passphrase for the\n"
-  "new key.  When a --passwd-nonce is used, the corresponding cached\n"
-  "passphrase is used to protect the new key.";
+  "new key.  If a --passwd-nonce is used, the corresponding cached\n"
+  "passphrase is used to protect the new key.  If --timestamp is given\n"
+  "its value is recorded as the key's creation time; the value is\n"
+  "expected in ISO format (e.g. \"20030316T120000\").";
 static gpg_error_t
 cmd_genkey (assuan_context_t ctx, char *line)
 {
@@ -870,6 +872,8 @@ cmd_genkey (assuan_context_t ctx, char *line)
   int opt_inq_passwd;
   size_t n;
   char *p, *pend;
+  const char *s;
+  time_t opt_timestamp;
   int c;
 
   if (ctrl->restricted)
@@ -893,6 +897,22 @@ cmd_genkey (assuan_context_t ctx, char *line)
           goto leave;
         }
     }
+  if ((s=has_option_name (line, "--timestamp")))
+    {
+      if (*s != '=')
+        {
+          rc = set_error (GPG_ERR_ASS_PARAMETER, "missing value for option");
+          goto leave;
+        }
+      opt_timestamp = isotime2epoch (s+1);
+      if (opt_timestamp < 1)
+        {
+          rc = set_error (GPG_ERR_ASS_PARAMETER, "invalid time value");
+          goto leave;
+        }
+    }
+  else
+    opt_timestamp = 0;
   line = skip_options (line);
 
   for (p=line; *p && *p != ' ' && *p != '\t'; p++)
@@ -932,7 +952,8 @@ cmd_genkey (assuan_context_t ctx, char *line)
   else if (passwd_nonce)
     newpasswd = agent_get_cache (ctrl, passwd_nonce, CACHE_MODE_NONCE);
 
-  rc = agent_genkey (ctrl, cache_nonce, (char*)value, valuelen, no_protection,
+  rc = agent_genkey (ctrl, cache_nonce, opt_timestamp,
+                     (char*)value, valuelen, no_protection,
                      newpasswd, opt_preset, &outbuf);
 
  leave:
@@ -2176,7 +2197,8 @@ cmd_keywrap_key (assuan_context_t ctx, char *line)
 
 
 static const char hlp_import_key[] =
-  "IMPORT_KEY [--unattended] [--force] [<cache_nonce>]\n"
+  "IMPORT_KEY [--unattended] [--force] [--timestamp=<isodate>]\n"
+  "           [<cache_nonce>]\n"
   "\n"
   "Import a secret key into the key store.  The key is expected to be\n"
   "encrypted using the current session's key wrapping key (cf. command\n"
@@ -2184,13 +2206,16 @@ static const char hlp_import_key[] =
   "no arguments but uses the inquiry \"KEYDATA\" to ask for the actual\n"
   "key data.  The unwrapped key must be a canonical S-expression.  The\n"
   "option --unattended tries to import the key as-is without any\n"
-  "re-encryption.  Existing key can be overwritten with --force.";
+  "re-encryption.  An existing key can be overwritten with --force.\n"
+  "If --timestamp is given its value is recorded as the key's creation\n"
+  "time; the value is expected in ISO format (e.g. \"20030316T120000\").";
 static gpg_error_t
 cmd_import_key (assuan_context_t ctx, char *line)
 {
   ctrl_t ctrl = assuan_get_pointer (ctx);
   gpg_error_t err;
   int opt_unattended;
+  time_t opt_timestamp;
   int force;
   unsigned char *wrappedkey = NULL;
   size_t wrappedkeylen;
@@ -2204,6 +2229,7 @@ cmd_import_key (assuan_context_t ctx, char *line)
   gcry_sexp_t openpgp_sexp = NULL;
   char *cache_nonce = NULL;
   char *p;
+  const char *s;
 
   if (ctrl->restricted)
     return leave_cmd (ctx, gpg_error (GPG_ERR_FORBIDDEN));
@@ -2216,6 +2242,22 @@ cmd_import_key (assuan_context_t ctx, char *line)
 
   opt_unattended = has_option (line, "--unattended");
   force = has_option (line, "--force");
+  if ((s=has_option_name (line, "--timestamp")))
+    {
+      if (*s != '=')
+        {
+          err = set_error (GPG_ERR_ASS_PARAMETER, "missing value for option");
+          goto leave;
+        }
+      opt_timestamp = isotime2epoch (s+1);
+      if (opt_timestamp < 1)
+        {
+          err = set_error (GPG_ERR_ASS_PARAMETER, "invalid time value");
+          goto leave;
+        }
+    }
+  else
+    opt_timestamp = 0;
   line = skip_options (line);
 
   for (p=line; *p && *p != ' ' && *p != '\t'; p++)
@@ -2287,7 +2329,6 @@ cmd_import_key (assuan_context_t ctx, char *line)
         goto leave; /* Note that ERR is still set.  */
     }
 
-
   if (openpgp_sexp)
     {
       /* In most cases the key is encrypted and thus the conversion
@@ -2351,10 +2392,12 @@ cmd_import_key (assuan_context_t ctx, char *line)
       err = agent_protect (key, passphrase, &finalkey, &finalkeylen,
                            ctrl->s2k_count, -1);
       if (!err)
-        err = agent_write_private_key (grip, finalkey, finalkeylen, force);
+        err = agent_write_private_key (grip, finalkey, finalkeylen, force,
+                                       opt_timestamp);
     }
   else
-    err = agent_write_private_key (grip, key, realkeylen, force);
+    err = agent_write_private_key (grip, key, realkeylen, force,
+                                   opt_timestamp);
 
  leave:
   gcry_sexp_release (openpgp_sexp);
diff --git a/agent/cvt-openpgp.c b/agent/cvt-openpgp.c
index 06cd1c840..758eab9ab 100644
--- a/agent/cvt-openpgp.c
+++ b/agent/cvt-openpgp.c
@@ -1067,7 +1067,7 @@ convert_from_openpgp_native (ctrl_t ctrl,
           if (!agent_protect (*r_key, passphrase,
                               &protectedkey, &protectedkeylen,
                               ctrl->s2k_count, -1))
-            agent_write_private_key (grip, protectedkey, protectedkeylen, 1);
+            agent_write_private_key (grip, protectedkey, protectedkeylen, 1, 0);
           xfree (protectedkey);
         }
       else
@@ -1076,7 +1076,7 @@ convert_from_openpgp_native (ctrl_t ctrl,
           agent_write_private_key (grip,
                                    *r_key,
                                    gcry_sexp_canon_len (*r_key, 0, NULL,NULL),
-                                   1);
+                                   1, 0);
         }
     }
 
diff --git a/agent/findkey.c b/agent/findkey.c
index bdb6ab4f5..fa09d645a 100644
--- a/agent/findkey.c
+++ b/agent/findkey.c
@@ -54,8 +54,8 @@ struct try_unprotect_arg_s
 
 /* Note: Ownership of FNAME and FP are moved to this function.  */
 static gpg_error_t
-write_extended_private_key (char *fname, estream_t fp, int update,
-                            const void *buf, size_t len)
+write_extended_private_key (char *fname, estream_t fp, int update, int newkey,
+                            const void *buf, size_t len, time_t timestamp)
 {
   gpg_error_t err;
   nvc_t pk = NULL;
@@ -93,6 +93,19 @@ write_extended_private_key (char *fname, estream_t fp, int update,
   if (err)
     goto leave;
 
+  /* If a timestamp has been supplied and the key is new write a
+   * creation timestamp.  (We double check that there is no Created
+   * item yet.)*/
+  if (timestamp && newkey && !nvc_lookup (pk, "Created:"))
+    {
+      gnupg_isotime_t timebuf;
+
+      epoch2isotime (timebuf, timestamp);
+      err = nvc_add (pk, "Created:", timebuf);
+      if (err)
+        goto leave;
+    }
+
   err = es_fseek (fp, 0, SEEK_SET);
   if (err)
     goto leave;
@@ -136,11 +149,13 @@ write_extended_private_key (char *fname, estream_t fp, int update,
 }
 
 /* Write an S-expression formatted key to our key storage.  With FORCE
-   passed as true an existing key with the given GRIP will get
-   overwritten.  */
+ * passed as true an existing key with the given GRIP will get
+ * overwritten.  If TIMESTAMP is not zero and the key does not yet
+ * exists it will be recorded as creation date.  */
 int
 agent_write_private_key (const unsigned char *grip,
-                         const void *buffer, size_t length, int force)
+                         const void *buffer, size_t length,
+                         int force, time_t timestamp)
 {
   char *fname;
   estream_t fp;
@@ -208,17 +223,20 @@ agent_write_private_key (const unsigned char *grip,
       if (first != '(')
         {
           /* Key is already in the extended format.  */
-          return write_extended_private_key (fname, fp, 1, buffer, length);
+          return write_extended_private_key (fname, fp, 1, 0, buffer, length,
+                                             timestamp);
         }
       if (first == '(' && opt.enable_extended_key_format)
         {
           /* Key is in the old format - but we want the extended format.  */
-          return write_extended_private_key (fname, fp, 0, buffer, length);
+          return write_extended_private_key (fname, fp, 0, 0, buffer, length,
+                                             timestamp);
         }
     }
 
   if (opt.enable_extended_key_format)
-    return write_extended_private_key (fname, fp, 0, buffer, length);
+    return write_extended_private_key (fname, fp, 0, 1, buffer, length,
+                                       timestamp);
 
   if (es_fwrite (buffer, length, 1, fp) != 1)
     {
@@ -1596,7 +1614,7 @@ agent_write_shadow_key (const unsigned char *grip,
     }
 
   len = gcry_sexp_canon_len (shdkey, 0, NULL, NULL);
-  err = agent_write_private_key (grip, shdkey, len, force);
+  err = agent_write_private_key (grip, shdkey, len, force, 0);
   xfree (shdkey);
   if (err)
     log_error ("error writing key: %s\n", gpg_strerror (err));
diff --git a/agent/genkey.c b/agent/genkey.c
index cddd67d9a..5c6ae9355 100644
--- a/agent/genkey.c
+++ b/agent/genkey.c
@@ -33,7 +33,7 @@
 
 static int
 store_key (gcry_sexp_t private, const char *passphrase, int force,
-	unsigned long s2k_count)
+           unsigned long s2k_count, time_t timestamp)
 {
   int rc;
   unsigned char *buf;
@@ -68,7 +68,7 @@ store_key (gcry_sexp_t private, const char *passphrase, int force,
       buf = p;
     }
 
-  rc = agent_write_private_key (grip, buf, len, force);
+  rc = agent_write_private_key (grip, buf, len, force, timestamp);
   xfree (buf);
   return rc;
 }
@@ -441,9 +441,11 @@ agent_ask_new_passphrase (ctrl_t ctrl, const char *prompt,
    KEYPARAM.  If CACHE_NONCE is given first try to lookup a passphrase
    using the cache nonce.  If NO_PROTECTION is true the key will not
    be protected by a passphrase.  If OVERRIDE_PASSPHRASE is true that
-   passphrase will be used for the new key.  */
+   passphrase will be used for the new key.  If TIMESTAMP is not zero
+   it will be recorded as creation date of the key (unless extended
+   format is disabled) . */
 int
-agent_genkey (ctrl_t ctrl, const char *cache_nonce,
+agent_genkey (ctrl_t ctrl, const char *cache_nonce, time_t timestamp,
               const char *keyparam, size_t keyparamlen, int no_protection,
               const char *override_passphrase, int preset, membuf_t *outbuf)
 {
@@ -517,7 +519,7 @@ agent_genkey (ctrl_t ctrl, const char *cache_nonce,
   /* store the secret key */
   if (DBG_CRYPTO)
     log_debug ("storing private key\n");
-  rc = store_key (s_private, passphrase, 0, ctrl->s2k_count);
+  rc = store_key (s_private, passphrase, 0, ctrl->s2k_count, timestamp);
   if (!rc)
     {
       if (!cache_nonce)
@@ -591,7 +593,7 @@ agent_protect_and_store (ctrl_t ctrl, gcry_sexp_t s_skey,
     {
       /* Take an empty string as request not to protect the key.  */
       err = store_key (s_skey, **passphrase_addr? *passphrase_addr:NULL, 1,
-	      ctrl->s2k_count);
+                       ctrl->s2k_count, 0);
     }
   else
     {
@@ -606,7 +608,7 @@ agent_protect_and_store (ctrl_t ctrl, gcry_sexp_t s_skey,
                                       L_("Please enter the new passphrase"),
                                       &pass);
       if (!err)
-        err = store_key (s_skey, pass, 1, ctrl->s2k_count);
+        err = store_key (s_skey, pass, 1, ctrl->s2k_count, 0);
       if (!err && passphrase_addr)
         *passphrase_addr = pass;
       else
diff --git a/agent/keyformat.txt b/agent/keyformat.txt
index 2e48b346e..c15e4f8d1 100644
--- a/agent/keyformat.txt
+++ b/agent/keyformat.txt
@@ -79,6 +79,42 @@ of a continuation line encodes a newline.
 Lines containing only whitespace, and lines starting with whitespace
 followed by '#' are considered to be comments and are ignored.
 
+** Well defined names
+
+*** Description
+This is a human readable string describing the key.
+
+*** Key
+The name "Key" is special in that it is mandatory and must occur only
+once.  The associated value holds the actual S-expression with the
+cryptographic key.  The S-expression is formatted using the 'Advanced
+Format' (GCRYSEXP_FMT_ADVANCED) that avoids non-printable characters
+so that the file can be easily inspected and edited.  See section
+'Private Key Format' below for details.
+
+*** Created
+The UTC time the key was created in ISO compressed format
+(yyyymmddThhmmss).  This informarion can be used to re-create an
+OpenPGP key.
+
+*** Label
+This is a short human readable description for the key which can be
+used by the software to describe the key in a user interface.  For
+example as part of the description in a prompt for a PIN or
+passphrase.  It is often used instead of a comment element as present
+in the S-expression of the "Key" item.
+
+*** OpenSSH-cert
+This takes a base64 encoded string wrapped so that this
+key file can be easily edited with a standard editor.  Several of such
+items can be used.
+
+*** Use-for-ssh
+If given and the value is "yes" or "1" the key is allowed for use by
+gpg-agent's ssh-agent implementation.  This is thus the same as
+putting the keygrip into the 'sshcontrol' file.  Only one such item
+should exist.
+
 * Private Key Format
 ** Unprotected Private Key Format
 
diff --git a/agent/protect-tool.c b/agent/protect-tool.c
index 00c0748e1..0ba31c1a0 100644
--- a/agent/protect-tool.c
+++ b/agent/protect-tool.c
@@ -805,12 +805,14 @@ agent_askpin (ctrl_t ctrl,
  * to stdout. */
 int
 agent_write_private_key (const unsigned char *grip,
-                         const void *buffer, size_t length, int force)
+                         const void *buffer, size_t length, int force,
+                         time_t timestamp)
 {
   char hexgrip[40+4+1];
   char *p;
 
   (void)force;
+  (void)timestamp;
 
   bin2hex (grip, 20, hexgrip);
   strcpy (hexgrip+40, ".key");