diff --git a/tools/gpg-auth.c b/tools/gpg-auth.c
index eafe125bf..cc8cc3943 100644
--- a/tools/gpg-auth.c
+++ b/tools/gpg-auth.c
@@ -1,944 +1,962 @@
/* gpg-auth.c - Authenticate using GnuPG
* Copyright (C) 2022 g10 Code GmbH
*
* This file is part of GnuPG.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This file is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see .
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#include
#include
#include
#include
#define INCLUDED_BY_MAIN_MODULE 1
#include "../common/util.h"
#include "../common/status.h"
#include "../common/i18n.h"
#include "../common/init.h"
#include "../common/sysutils.h"
#include "../common/asshelp.h"
#include "../common/session-env.h"
#include "../common/membuf.h"
#include "../common/exechelp.h"
/* We keep all global options in the structure OPT. */
struct
{
int interactive;
int verbose;
unsigned int debug;
int quiet;
int with_colons;
const char *agent_program;
int autostart;
/* Options passed to the gpg-agent: */
char *lc_ctype;
char *lc_messages;
} opt;
/* Debug values and macros. */
#define DBG_IPC_VALUE 1024 /* Debug assuan communication. */
#define DBG_EXTPROG_VALUE 16384 /* Debug external program calls */
#define DBG_IPC (opt.debug & DBG_IPC_VALUE)
#define DBG_EXTPROG (opt.debug & DBG_EXTPROG_VALUE)
/* Constants to identify the commands and options. */
enum opt_values
{
aNull = 0,
oQuiet = 'q',
oVerbose = 'v',
oDebug = 500,
oGpgProgram,
oGpgsmProgram,
oAgentProgram,
oStatusFD,
oWithColons,
oNoAutostart,
oLCctype,
oLCmessages,
oChUid,
oDummy
};
/* The list of commands and options. */
static gpgrt_opt_t opts[] = {
ARGPARSE_group (301, ("@\nOptions:\n ")),
ARGPARSE_s_n (oVerbose, "verbose", ("verbose")),
ARGPARSE_s_n (oQuiet, "quiet", ("be somewhat more quiet")),
ARGPARSE_s_s (oDebug, "debug", "@"),
ARGPARSE_s_i (oStatusFD, "status-fd", N_("|FD|write status info to this FD")),
ARGPARSE_s_n (oWithColons, "with-colons", "@"),
ARGPARSE_s_n (oNoAutostart, "no-autostart", "@"),
ARGPARSE_s_s (oAgentProgram, "agent-program", "@"),
ARGPARSE_s_s (oLCctype, "lc-ctype", "@"),
ARGPARSE_s_s (oLCmessages, "lc-messages","@"),
ARGPARSE_end ()
};
/* The list of supported debug flags. */
static struct debug_flags_s debug_flags [] =
{
{ DBG_IPC_VALUE , "ipc" },
{ DBG_EXTPROG_VALUE, "extprog" },
{ 0, NULL }
};
/* Print usage information and provide strings for help. */
static const char *
my_strusage( int level )
{
const char *p;
switch (level)
{
case 9: p = "GPL-3.0-or-later"; break;
case 11: p = "gpg-auth"; break;
case 12: p = "@GNUPG@"; break;
case 13: p = VERSION; break;
case 14: p = GNUPG_DEF_COPYRIGHT_LINE; break;
case 17: p = PRINTABLE_OS_NAME; break;
case 19: p = ("Please report bugs to <@EMAIL@>.\n"); break;
case 1:
case 40:
p = ("Usage: gpg-auth"
" [options] (-h for help)");
break;
case 41:
p = ("Syntax: gpg-auth"
" [options] \n\n"
"Tool to authenticate a user using a smartcard.\n"
"Use command \"help\" to list all commands.");
break;
default: p = NULL; break;
}
return p;
}
/* Command line parsing. */
static void
parse_arguments (gpgrt_argparse_t *pargs, gpgrt_opt_t *popts)
{
while (gpgrt_argparse (NULL, pargs, popts))
{
switch (pargs->r_opt)
{
case oQuiet: opt.quiet = 1; break;
case oVerbose: opt.verbose++; break;
case oDebug:
if (parse_debug_flag (pargs->r.ret_str, &opt.debug, debug_flags))
{
pargs->r_opt = ARGPARSE_INVALID_ARG;
pargs->err = ARGPARSE_PRINT_ERROR;
}
break;
case oAgentProgram: opt.agent_program = pargs->r.ret_str; break;
case oStatusFD:
gnupg_set_status_fd (translate_sys2libc_fd_int (pargs->r.ret_int, 1));
break;
case oWithColons: opt.with_colons = 1; break;
case oNoAutostart: opt.autostart = 0; break;
case oLCctype: opt.lc_ctype = pargs->r.ret_str; break;
case oLCmessages: opt.lc_messages = pargs->r.ret_str; break;
default: pargs->err = ARGPARSE_PRINT_ERROR; break;
}
}
}
struct ga_key_list {
struct ga_key_list *next;
char keygrip[41]; /* Keygrip to identify a key. */
size_t pubkey_len;
char *pubkey; /* Public key in SSH format. */
+ char *comment;
};
/* Local prototypes. */
static gpg_error_t scd_passwd_reset (assuan_context_t ctx, const char *keygrip);
static gpg_error_t ga_scd_connect (assuan_context_t *r_scd_ctx, int use_agent);
static gpg_error_t ga_scd_get_auth_keys (assuan_context_t ctx,
struct ga_key_list **r_key_list);
static gpg_error_t ga_filter_by_authorized_keys (struct ga_key_list **r_key_list);
static void ga_release_auth_keys (struct ga_key_list *key_list);
static gpg_error_t scd_pkauth (assuan_context_t ctx, const char *keygrip);
static gpg_error_t authenticate (assuan_context_t ctx, struct ga_key_list *key_list);
-static int getpin (const char *info, char *buf, size_t *r_len);
+static int getpin (assuan_context_t ctx, const char *info, char *buf, size_t *r_len);
/* gpg-auth main. */
int
main (int argc, char **argv)
{
gpg_error_t err;
gpgrt_argparse_t pargs;
assuan_context_t scd_ctx = NULL;
struct ga_key_list *key_list = NULL;
gnupg_reopen_std ("gpg-auth");
gpgrt_set_strusage (my_strusage);
log_set_prefix ("gpg-auth", GPGRT_LOG_WITH_PREFIX);
/* Make sure that our subsystems are ready. */
i18n_init();
init_common_subsystems (&argc, &argv);
assuan_set_gpg_err_source (GPG_ERR_SOURCE_DEFAULT);
setup_libassuan_logging (&opt.debug, NULL);
/* Setup default options. */
opt.autostart = 1;
/* Parse the command line. */
pargs.argc = &argc;
pargs.argv = &argv;
pargs.flags = ARGPARSE_FLAG_KEEP;
parse_arguments (&pargs, opts);
gpgrt_argparse (NULL, &pargs, NULL); /* Release internal state. */
if (log_get_errorcount (0))
exit (2);
if (argc != 0)
gpgrt_usage (1); /* Never returns. */
err = ga_scd_connect (&scd_ctx, 1);
if (!err)
err = ga_scd_get_auth_keys (scd_ctx, &key_list);
if (!err)
err = ga_filter_by_authorized_keys (&key_list);
if (!err)
err = authenticate (scd_ctx, key_list);
ga_release_auth_keys (key_list);
if (scd_ctx)
assuan_release (scd_ctx);
if (err)
exit (1);
return 0;
}
static gpg_error_t
authenticate (assuan_context_t ctx, struct ga_key_list *key_list)
{
gpg_error_t err;
while (key_list)
{
err = scd_passwd_reset (ctx, key_list->keygrip);
if (err)
return err;
+ assuan_set_pointer (ctx, key_list->comment);
err = scd_pkauth (ctx, key_list->keygrip);
if (!err)
/* Success! */
return 0;
key_list = key_list->next;
}
return gpg_error (GPG_ERR_NOT_FOUND);
}
static gpg_error_t
get_serialno_cb (void *opaque, const char *line)
{
char **serialno = opaque;
const char *keyword = line;
const char *s;
int keywordlen, n;
for (keywordlen=0; *line && !spacep (line); line++, keywordlen++)
;
while (spacep (line))
line++;
if (keywordlen == 8 && !memcmp (keyword, "SERIALNO", keywordlen))
{
if (*serialno)
return gpg_error (GPG_ERR_CONFLICT); /* Unexpected status line. */
for (n=0,s=line; hexdigitp (s); s++, n++)
;
if (!n || (n&1)|| !(spacep (s) || !*s) )
return gpg_error (GPG_ERR_ASS_PARAMETER);
*serialno = xtrymalloc (n+1);
if (!*serialno)
return gpg_error_from_syserror ();
memcpy (*serialno, line, n);
(*serialno)[n] = 0;
}
return 0;
}
/* Helper function, which is used by scd_connect.
Try to retrieve the SCDaemon's socket name from the gpg-agent
context CTX. On success, *SOCKET_NAME is filled with a copy of the
socket name. Return proper error code or zero on success. */
static gpg_error_t
agent_scd_getinfo_socket_name (assuan_context_t ctx, char **socket_name)
{
membuf_t data;
gpg_error_t err = 0;
unsigned char *databuf;
size_t datalen;
init_membuf (&data, 256);
*socket_name = NULL;
err = assuan_transact (ctx, "SCD GETINFO socket_name", put_membuf_cb, &data,
NULL, NULL, NULL, NULL);
databuf = get_membuf (&data, &datalen);
if (!err)
{
if (databuf && datalen)
{
char *res = xtrymalloc (datalen + 1);
if (!res)
err = gpg_error_from_syserror ();
else
{
memcpy (res, databuf, datalen);
res[datalen] = 0;
*socket_name = res;
}
}
}
xfree (databuf);
return err;
}
/* Callback parameter for learn card */
struct learn_parm_s
{
void (*kpinfo_cb)(void*, const char *);
void *kpinfo_cb_arg;
void (*certinfo_cb)(void*, const char *);
void *certinfo_cb_arg;
void (*sinfo_cb)(void*, const char *, size_t, const char *);
void *sinfo_cb_arg;
};
/* Connect to the agent and send the standard options. */
static gpg_error_t
start_agent (assuan_context_t *ctx_p)
{
gpg_error_t err;
session_env_t session_env;
session_env = session_env_new ();
if (!session_env)
log_fatal ("error allocating session environment block: %s\n",
strerror (errno));
err = start_new_gpg_agent (ctx_p,
GPG_ERR_SOURCE_DEFAULT,
opt.agent_program,
NULL, NULL,
session_env,
opt.autostart,
!opt.quiet, 0,
NULL, NULL);
session_env_release (session_env);
return err;
}
static gpg_error_t
scd_serialno (assuan_context_t ctx)
{
char *serialno = NULL;
gpg_error_t err;
err = assuan_transact (ctx, "SERIALNO", NULL, NULL, NULL, NULL,
get_serialno_cb, &serialno);
xfree (serialno);
return err;
}
static gpg_error_t
scd_passwd_reset (assuan_context_t ctx, const char *keygrip)
{
char line[ASSUAN_LINELENGTH];
gpg_error_t err;
snprintf (line, DIM(line), "PASSWD --clear OPENPGP.2 %s", keygrip);
err = assuan_transact (ctx, line, NULL, NULL, NULL, NULL,
NULL, NULL);
return err;
}
/* Connect to scdaemon by pipe or socket. Execute initial "SEREIALNO"
command to enable all connected token under scdaemon control. */
static gpg_error_t
ga_scd_connect (assuan_context_t *r_scd_ctx, int use_agent)
{
assuan_context_t assuan_ctx;
gpg_error_t err;
err = assuan_new (&assuan_ctx);
if (err)
return err;
if (use_agent)
/* Use scdaemon under gpg-agent. */
{
char *scd_socket_name = NULL;
assuan_context_t ctx;
err = start_agent (&ctx);
if (err)
return err;
/* Note that if gpg-agent is there but no scdaemon yet,
* gpg-agent automatically invokes scdaemon by this query
* itself.
*/
err = agent_scd_getinfo_socket_name (ctx, &scd_socket_name);
assuan_release (ctx);
if (!err)
err = assuan_socket_connect (assuan_ctx, scd_socket_name, 0, 0);
if (!err && DBG_IPC)
log_debug ("got scdaemon socket name from gpg-agent, "
"connected to socket '%s'", scd_socket_name);
xfree (scd_socket_name);
}
else
{
const char *scd_path;
const char *pgmname;
const char *argv[3];
int no_close_list[2];
scd_path = gnupg_module_name (GNUPG_MODULE_NAME_SCDAEMON);
if (!(pgmname = strrchr (scd_path, '/')))
pgmname = scd_path;
else
pgmname++;
/* Fill argument vector for scdaemon. */
argv[0] = pgmname;
argv[1] = "--server";
argv[2] = NULL;
no_close_list[0] = assuan_fd_from_posix_fd (fileno (stderr));
no_close_list[1] = ASSUAN_INVALID_FD;
/* Connect to the scdaemon */
err = assuan_pipe_connect (assuan_ctx, scd_path, argv, no_close_list,
NULL, NULL, 0);
if (err)
{
log_error ("could not spawn scdaemon: %s", gpg_strerror (err));
return err;
}
if (DBG_IPC)
log_debug ("spawned a new scdaemon (path: '%s')", scd_path);
}
if (err)
assuan_release (assuan_ctx);
else
{
scd_serialno (assuan_ctx);
*r_scd_ctx = assuan_ctx;
}
return err;
}
/* Handle the NEEDPIN inquiry. */
static gpg_error_t
inq_needpin (void *opaque, const char *line)
{
assuan_context_t ctx = opaque;
const char *s;
char *pin;
size_t pinlen;
int rc;
rc = 0;
if ((s = has_leading_keyword (line, "NEEDPIN")))
{
line = s;
pinlen = 90;
pin = gcry_malloc_secure (pinlen);
if (!pin)
return out_of_core ();
- rc = getpin (line, pin, &pinlen);
+ rc = getpin (ctx, line, pin, &pinlen);
if (!rc)
{
assuan_begin_confidential (ctx);
rc = assuan_send_data (ctx, pin, pinlen);
assuan_end_confidential (ctx);
}
wipememory (pin, pinlen);
xfree (pin);
}
else if ((s = has_leading_keyword (line, "POPUPPINPADPROMPT")))
{
/* i 18 */;
/* Please use PINPAD! */;
}
else if ((s = has_leading_keyword (line, "DISMISSPINPADPROMPT")))
{
;
}
else
{
log_error ("unsupported inquiry '%s'\n", line);
rc = gpg_error (GPG_ERR_ASS_UNKNOWN_INQUIRE);
}
return gpg_error (rc);
}
struct card_keyinfo_parm_s {
int error;
struct ga_key_list *list;
};
/* Callback function for scd_keyinfo_list. */
static gpg_error_t
card_keyinfo_cb (void *opaque, const char *line)
{
gpg_error_t err = 0;
struct card_keyinfo_parm_s *parm = opaque;
const char *keyword = line;
int keywordlen;
struct ga_key_list *keyinfo = NULL;
for (keywordlen=0; *line && !spacep (line); line++, keywordlen++)
;
while (spacep (line))
line++;
if (keywordlen == 7 && !memcmp (keyword, "KEYINFO", keywordlen))
{
const char *s;
int n;
struct ga_key_list **l_p = &parm->list;
/* It's going to append the information at the end. */
while ((*l_p))
l_p = &(*l_p)->next;
keyinfo = xtrycalloc (1, sizeof *keyinfo);
if (!keyinfo)
goto alloc_error;
for (n=0,s=line; hexdigitp (s); s++, n++)
;
if (n != 40)
goto parm_error;
memcpy (keyinfo->keygrip, line, 40);
keyinfo->keygrip[40] = 0;
line = s;
if (!*line)
goto parm_error;
while (spacep (line))
line++;
if (*line++ != 'T')
goto parm_error;
if (!*line)
goto parm_error;
while (spacep (line))
line++;
for (n=0,s=line; hexdigitp (s); s++, n++)
;
if (!n)
goto skip;
skip:
*l_p = keyinfo;
}
return err;
alloc_error:
xfree (keyinfo);
if (!parm->error)
parm->error = gpg_error_from_syserror ();
return 0;
parm_error:
xfree (keyinfo);
if (!parm->error)
parm->error = gpg_error (GPG_ERR_ASS_PARAMETER);
return 0;
}
/* Call the scdaemon to retrieve list of available keys on cards. On
success, the allocated structure is stored at R_KEY_LIST. On
error, an error code is returned and NULL is stored at R_KEY_LIST. */
static gpg_error_t
scd_keyinfo_list (assuan_context_t ctx, struct ga_key_list **r_key_list)
{
int err;
struct card_keyinfo_parm_s parm;
memset (&parm, 0, sizeof parm);
err = assuan_transact (ctx, "KEYINFO --list=auth", NULL, NULL, NULL, NULL,
card_keyinfo_cb, &parm);
if (!err && parm.error)
err = parm.error;
if (!err)
*r_key_list = parm.list;
else
ga_release_auth_keys (parm.list);
return err;
}
/* A variant of put_membuf_cb, which only put the second field. */
static gpg_error_t
put_second_field_cb (void *opaque, const void *buf, size_t len)
{
char line[ASSUAN_LINELENGTH];
membuf_t *data = opaque;
if (buf && len < ASSUAN_LINELENGTH)
{
const char *fields[3];
size_t field_len;
memcpy (line, buf, len);
if (split_fields (line, fields, DIM (fields)) < 2)
return 0;
field_len = strlen (fields[1]);
put_membuf (data, fields[1], field_len);
}
return 0;
}
static gpg_error_t
scd_get_pubkey (assuan_context_t ctx, struct ga_key_list *key)
{
char line[ASSUAN_LINELENGTH];
membuf_t data;
unsigned char *databuf;
size_t datalen;
gpg_error_t err = 0;
init_membuf (&data, 256);
snprintf (line, DIM(line), "READKEY --format=ssh %s", key->keygrip);
err = assuan_transact (ctx, line, put_second_field_cb, &data,
NULL, NULL, NULL, NULL);
databuf = get_membuf (&data, &datalen);
if (!err)
{
key->pubkey_len = datalen;
key->pubkey = databuf;
}
else
xfree (databuf);
return err;
}
static gpg_error_t
ga_scd_get_auth_keys (assuan_context_t ctx, struct ga_key_list **r_key_list)
{
gpg_error_t err;
struct ga_key_list *kl, *key_list = NULL;
/* Get list of auth keys with their keygrips. */
err = scd_keyinfo_list (ctx, &key_list);
/* And retrieve public key for each key. */
kl = key_list;
while (kl)
{
err = scd_get_pubkey (ctx, kl);
if (err)
break;
kl = kl->next;
}
if (err)
ga_release_auth_keys (key_list);
else
*r_key_list = key_list;
return err;
}
struct ssh_key_list {
struct ssh_key_list *next;
char *pubkey; /* Public key in SSH format. */
+ char *comment;
};
static void
release_ssh_key_list (struct ssh_key_list *key_list)
{
struct ssh_key_list *key;
while (key_list)
{
key = key_list;
key_list = key_list->next;
xfree (key->pubkey);
+ xfree (key->comment);
xfree (key);
}
}
static gpg_error_t
ssh_authorized_keys (struct ssh_key_list **r_ssh_key_list)
{
gpg_error_t err = 0;
char *fname = NULL;
estream_t fp = NULL;
char *line = NULL;
size_t length_of_line = 0;
size_t maxlen;
ssize_t len;
const char *fields[3];
struct ssh_key_list *ssh_key_list = NULL;
struct ssh_key_list *ssh_key_prev = NULL;
struct ssh_key_list *ssh_key = NULL;
fname = make_absfilename_try ("~", ".ssh", "authorized_keys", NULL);
if (fname == NULL)
return gpg_error (GPG_ERR_INV_NAME);
fp = es_fopen (fname, "r");
if (!fp)
{
err = gpg_error_from_syserror ();
xfree (fname);
return err;
}
xfree (fname);
maxlen = 2048; /* Set limit. */
while ((len = es_read_line (fp, &line, &length_of_line, &maxlen)) > 0)
{
if (!maxlen)
{
err = gpg_error (GPG_ERR_LINE_TOO_LONG);
log_error (_("error reading '%s': %s\n"), fname, gpg_strerror (err));
goto leave;
}
/* Strip newline and carriage return, if present. */
while (len > 0 && (line[len - 1] == '\n' || line[len - 1] == '\r'))
line[--len] = '\0';
+ fields[2] = NULL;
if (split_fields (line, fields, DIM (fields)) < 2)
continue; /* Skip empty lines or line with only a field. */
if (*fields[0] == '#')
continue; /* Skip comments. */
ssh_key = xtrycalloc (1, sizeof *ssh_key);
if (!ssh_key)
{
err = gpg_error_from_syserror ();
release_ssh_key_list (ssh_key_list);
goto leave;
}
ssh_key->pubkey = strdup (fields[1]);
+ ssh_key->comment = strdup (fields[2]);
if (ssh_key_list)
ssh_key_prev->next = ssh_key;
else
ssh_key_list = ssh_key;
ssh_key_prev = ssh_key;
}
*r_ssh_key_list = ssh_key_list;
leave:
xfree (line);
es_fclose (fp);
return err;
}
static gpg_error_t
ga_filter_by_authorized_keys (struct ga_key_list **r_key_list)
{
gpg_error_t err;
struct ga_key_list *cur = *r_key_list;
struct ga_key_list *key_list = NULL;
struct ga_key_list *prev = NULL;
struct ssh_key_list *ssh_key_list = NULL;
err = ssh_authorized_keys (&ssh_key_list);
if (err)
return err;
if (ssh_key_list == NULL)
return gpg_error (GPG_ERR_NOT_FOUND);
while (cur)
{
struct ssh_key_list *skl = ssh_key_list;
while (skl)
if (!strncmp (cur->pubkey, skl->pubkey, cur->pubkey_len))
break;
else
skl = skl->next;
/* valid? */
if (skl)
{
if (key_list)
prev->next = cur;
else
key_list = cur;
+ cur->comment = skl->comment;
+ skl->comment = NULL;
prev = cur;
cur = cur->next;
}
else
{
struct ga_key_list *k = cur;
cur = cur->next;
xfree (k->pubkey);
xfree (k);
}
}
if (prev && prev->next)
prev->next = NULL;
release_ssh_key_list (ssh_key_list);
*r_key_list = key_list;
return 0;
}
static void
ga_release_auth_keys (struct ga_key_list *key_list)
{
struct ga_key_list *key;
while (key_list)
{
key = key_list;
key_list = key_list->next;
xfree (key->pubkey);
xfree (key);
}
}
static int
-getpin (const char *info, char *buf, size_t *r_len)
+getpin (assuan_context_t ctx, const char *info, char *buf, size_t *r_len)
{
int rc = 0;
char line[ASSUAN_LINELENGTH];
const char *fields[2];
+ const char *comment;
(void)info;
+ comment = assuan_get_pointer (ctx);
+ if (comment)
+ {
+ int msg_len = 5 + strlen (comment);
+ fprintf (stdout, "i %d\n", msg_len);
+ fprintf (stdout, "KEY: %s\n", comment);
+ fflush (stdout);
+ }
+
fputs ("P 18\n", stdout);
fputs ("Please input PIN: \n", stdout);
fflush (stdout);
fgets (line, ASSUAN_LINELENGTH, stdin);
if (split_fields (line, fields, DIM (fields)) < DIM (fields))
rc = GPG_ERR_PROTOCOL_VIOLATION;
else if (strcmp (fields[0], "p") != 0)
rc = GPG_ERR_CANCELED;
if (!fgets (line, ASSUAN_LINELENGTH, stdin))
rc = GPG_ERR_PROTOCOL_VIOLATION;
if (!rc)
{
size_t len = strlen (line);
/* Strip newline and carriage return, if present. */
while (len > 0 && (line[len - 1] == '\n' || line[len - 1] == '\r'))
line[--len] = '\0';
len++; /* Include last '\0' in the data. */
if (len > *r_len)
rc = GPG_ERR_BUFFER_TOO_SHORT;
else
memcpy (buf, line, len);
*r_len = len;
}
return rc;
}
static gpg_error_t
scd_pkauth (assuan_context_t ctx, const char *keygrip)
{
char line[ASSUAN_LINELENGTH];
gpg_error_t err;
snprintf (line, DIM(line), "PKAUTH --challenge-response %s", keygrip);
err = assuan_transact (ctx, line, NULL, NULL, inq_needpin, ctx,
NULL, NULL);
return err;
}