agent: New option --pinentry-formatted-passphrase

* agent/agent.h (opt): Add field pinentry_formatted_passphrase.
* agent/call-pinentry.c (setup_formatted_passphrase): New.
(agent_get_passphrase): Pass option to pinentry.
* agent/gpg-agent.c (oPinentryFormattedPassphrase): New.
(opts): Add option.
(parse_rereadable_options): Set option.
--

GnuPG-bug-id: 5517

agent/agent.h

@@ -108,6 +108,14 @@ struct
      upon this timeout value.  */
   unsigned long pinentry_timeout;
 
+  /* Mode for the formatted passphrase option to use by pinentry.
+     Possible values are:
+       0 - Option is not shown (and off).
+       1 - Option is shown, off by default, and user can change it.
+       2 - Option is shown, on, and user cannot change it.
+       3 - Option is shown, on by default, and user can change it.  */
+  unsigned int pinentry_formatted_passphrase;
+
   /* The default and maximum TTL of cache entries. */
   unsigned long def_cache_ttl;     /* Default. */
   unsigned long def_cache_ttl_ssh; /* for SSH. */

agent/call-pinentry.c

@@ -983,6 +983,67 @@ setup_genpin (ctrl_t ctrl)
 }
 
 
+/* Helper to setup pinentry for formatted passphrase. */
+static gpg_error_t
+setup_formatted_passphrase (ctrl_t ctrl)
+{
+  static const struct { const char *key, *help_id, *value; } tbl[] = {
+    /* TRANSLATORS: This is the text of an option (usually represented
+       by a checkbox) as used in pinentry.  */
+    { "label", "pinentry.formatted_passphrase.label",
+      N_("Format the passphrase") },
+    /* TRANSLATORS: This is the tooltip shown by pinentry when
+        hovering over the option for formatted passphrase.
+        The length is limited to about 900 characters.  */
+    { "tt",    "pinentry.formatted_passphrase.tooltip",
+      N_("Enable this option to make the passphrase easier readable by "
+         "grouping its characters.") },
+    /* TRANSLATORS: This is a text shown by pinentry if the option
+        for formatted passphrase is enabled.  The length is
+        limited to about 900 characters.  */
+    { "hint",  "pinentry.formatted_passphrase.hint",
+      N_("Note: The blanks are not part of the passphrase.") },
+    { NULL, NULL }
+  };
+
+  gpg_error_t rc;
+  char line[ASSUAN_LINELENGTH];
+  int idx;
+  char *tmpstr;
+  const char *s;
+
+  (void)ctrl;
+
+  if (opt.pinentry_formatted_passphrase)
+    {
+      snprintf (line, DIM(line), "OPTION formatted-passphrase=%d",
+                opt.pinentry_formatted_passphrase);
+      rc = assuan_transact (entry_ctx, line, NULL, NULL, NULL, NULL, NULL,
+                            NULL);
+      if (rc && gpg_err_code (rc) != GPG_ERR_UNKNOWN_OPTION)
+        return rc;
+
+      for (idx=0; tbl[idx].key; idx++)
+        {
+          tmpstr = gnupg_get_help_string (tbl[idx].help_id, 0);
+          if (tmpstr)
+            s = tmpstr;
+          else
+            s = L_(tbl[idx].value);
+          snprintf (line, DIM(line), "OPTION formatted-passphrase-%s=%s",
+                    tbl[idx].key, s);
+          xfree (tmpstr);
+          rc = assuan_transact (entry_ctx, line, NULL, NULL, NULL, NULL, NULL,
+                                NULL);
+          if (rc && gpg_err_code (rc) != GPG_ERR_UNKNOWN_OPTION)
+            return rc;
+        }
+    }
+
+  return 0;
+}
+
+
 /* Helper for agent_askpin and agent_get_passphrase.  */
 static gpg_error_t
 setup_qualitybar (ctrl_t ctrl)
@@ -1556,6 +1617,10 @@ agent_get_passphrase (ctrl_t ctrl,
         return unlock_pinentry (ctrl, rc);
     }
 
+  rc = setup_formatted_passphrase (ctrl);
+  if (rc)
+    return unlock_pinentry (ctrl, rc);
+
   if (!pininfo)
     {
       /* Legacy method without PININFO.  */

agent/gpg-agent.c

@@ -96,6 +96,7 @@ enum cmd_and_opt_values
   oPinentryTouchFile,
   oPinentryInvisibleChar,
   oPinentryTimeout,
+  oPinentryFormattedPassphrase,
   oDisplay,
   oTTYname,
   oTTYtype,
@@ -284,6 +285,8 @@ static gpgrt_opt_t opts[] = {
   ARGPARSE_s_s (oPinentryInvisibleChar, "pinentry-invisible-char", "@"),
   ARGPARSE_s_u (oPinentryTimeout, "pinentry-timeout",
                 N_("|N|set the Pinentry timeout to N seconds")),
+  ARGPARSE_s_u (oPinentryFormattedPassphrase, "pinentry-formatted-passphrase",
+                "@"),
   ARGPARSE_s_n (oAllowEmacsPinentry,  "allow-emacs-pinentry",
                 N_("allow passphrase to be prompted through Emacs")),
 
@@ -849,6 +852,7 @@ parse_rereadable_options (gpgrt_argparse_t *pargs, int reread)
       xfree (opt.pinentry_invisible_char);
       opt.pinentry_invisible_char = NULL;
       opt.pinentry_timeout = 0;
+      opt.pinentry_formatted_passphrase = 0;
       memset (opt.daemon_program, 0, sizeof opt.daemon_program);
       opt.def_cache_ttl = DEFAULT_CACHE_TTL;
       opt.def_cache_ttl_ssh = DEFAULT_CACHE_TTL_SSH;
@@ -909,6 +913,9 @@ parse_rereadable_options (gpgrt_argparse_t *pargs, int reread)
       opt.pinentry_invisible_char = xtrystrdup (pargs->r.ret_str); break;
       break;
     case oPinentryTimeout: opt.pinentry_timeout = pargs->r.ret_ulong; break;
+    case oPinentryFormattedPassphrase:
+      opt.pinentry_formatted_passphrase = pargs->r.ret_ulong;
+      break;
 
     case oTpm2daemonProgram:
       opt.daemon_program[DAEMON_TPM2D] = pargs->r.ret_str;

doc/gpg-agent.texi

@@ -465,6 +465,30 @@ user input.  The default value of 0 does not ask the pinentry to
 timeout, however a Pinentry may use its own default timeout value in
 this case.  A Pinentry may or may not honor this request.
 
+@item --pinentry-formatted-passphrase @var{n}
+@opindex pinentry-formatted-passphrase
+This option asks the Pinentry to use the mode @var{n} for passphrase
+formatting when asking the user for a new passphrase.
+Possible values are:
+@table @code
+@item 0
+Passphrase formatting is disabled.  The option to change it is not shown,
+so that the user cannot turn it on.  This is the default.
+@item 1
+Passphrase formatting is disabled.  The option to change it is shown, so
+that the user can turn it on.
+@item 2
+Passphrase formatting is enabled. The option to change it is shown, but
+disabled, so that the user cannot turn it off.
+@item 3
+Passphrase formatting is enabled.  The option to change it is shown, so
+that the user can turn it off.
+@end table
+
+If passphrase formatting is enabled, then all non-breaking space characters
+are stripped from the entered passphrase.  Passphrase formatting is mostly
+useful in combination with passphrases generated with the GENPIN command.
+
 @item --pinentry-program @var{filename}
 @opindex pinentry-program
 Use program @var{filename} as the PIN entry.  The default is