Adding upstream version 2.2.40.upstream/2.2.40

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2475 insertions, 0 deletions

diff --git a/g10/export.c b/g10/export.c
new file mode 100644
index 0000000..e98af59
--- /dev/null
+++ b/g10/export.c
@@ -0,0 +1,2475 @@
+/* export.c - Export keys in the OpenPGP defined format.
+ * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
+ *               2005, 2010 Free Software Foundation, Inc.
+ * Copyright (C) 1998-2016  Werner Koch
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG 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.
+ *
+ * GnuPG 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 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 <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include "gpg.h"
+#include "options.h"
+#include "packet.h"
+#include "../common/status.h"
+#include "keydb.h"
+#include "../common/util.h"
+#include "main.h"
+#include "../common/i18n.h"
+#include "../common/membuf.h"
+#include "../common/host2net.h"
+#include "../common/zb32.h"
+#include "../common/recsel.h"
+#include "../common/mbox-util.h"
+#include "../common/init.h"
+#include "trustdb.h"
+#include "call-agent.h"
+#include "key-clean.h"
+
+
+/* An object to keep track of subkeys. */
+struct subkey_list_s
+{
+  struct subkey_list_s *next;
+  u32 kid[2];
+};
+typedef struct subkey_list_s *subkey_list_t;
+
+
+/* An object to track statistics for export operations.  */
+struct export_stats_s
+{
+  ulong count;            /* Number of processed keys.        */
+  ulong secret_count;     /* Number of secret keys seen.      */
+  ulong exported;         /* Number of actual exported keys.  */
+};
+
+
+/* A global variable to store the selector created from
+ * --export-filter keep-uid=EXPR.
+ * --export-filter drop-subkey=EXPR.
+ *
+ * FIXME: We should put this into the CTRL object but that requires a
+ * lot more changes right now.
+ */
+static recsel_expr_t export_keep_uid;
+static recsel_expr_t export_drop_subkey;
+
+
+/* An object used for a linked list to implement the
+ * push_export_filter/pop_export_filters functions.  */
+struct export_filter_attic_s
+{
+  struct export_filter_attic_s *next;
+  recsel_expr_t export_keep_uid;
+  recsel_expr_t export_drop_subkey;
+};
+static struct export_filter_attic_s *export_filter_attic;
+
+
+
+/* Local prototypes.  */
+static int do_export (ctrl_t ctrl, strlist_t users, int secret,
+                      unsigned int options, export_stats_t stats);
+static int do_export_stream (ctrl_t ctrl, iobuf_t out,
+                             strlist_t users, int secret,
+                             kbnode_t *keyblock_out, unsigned int options,
+			     export_stats_t stats, int *any);
+static gpg_error_t print_pka_or_dane_records
+/**/                 (iobuf_t out, kbnode_t keyblock, PKT_public_key *pk,
+                      const void *data, size_t datalen,
+                      int print_pka, int print_dane);
+
+
+static void
+cleanup_export_globals (void)
+{
+  recsel_release (export_keep_uid);
+  export_keep_uid = NULL;
+  recsel_release (export_drop_subkey);
+  export_drop_subkey = NULL;
+}
+
+
+/* Option parser for export options.  See parse_options fro
+   details.  */
+int
+parse_export_options(char *str,unsigned int *options,int noisy)
+{
+  struct parse_options export_opts[]=
+    {
+      {"export-local-sigs",EXPORT_LOCAL_SIGS,NULL,
+       N_("export signatures that are marked as local-only")},
+      {"export-attributes",EXPORT_ATTRIBUTES,NULL,
+       N_("export attribute user IDs (generally photo IDs)")},
+      {"export-sensitive-revkeys",EXPORT_SENSITIVE_REVKEYS,NULL,
+       N_("export revocation keys marked as \"sensitive\"")},
+      {"export-clean",EXPORT_CLEAN,NULL,
+       N_("remove unusable parts from key during export")},
+      {"export-minimal",EXPORT_MINIMAL|EXPORT_CLEAN,NULL,
+       N_("remove as much as possible from key during export")},
+
+      {"export-pka", EXPORT_PKA_FORMAT, NULL, NULL },
+      {"export-dane", EXPORT_DANE_FORMAT, NULL, NULL },
+
+      {"backup", EXPORT_BACKUP, NULL,
+       N_("use the GnuPG key backup format")},
+      {"export-backup", EXPORT_BACKUP, NULL, NULL },
+
+      /* Aliases for backward compatibility */
+      {"include-local-sigs",EXPORT_LOCAL_SIGS,NULL,NULL},
+      {"include-attributes",EXPORT_ATTRIBUTES,NULL,NULL},
+      {"include-sensitive-revkeys",EXPORT_SENSITIVE_REVKEYS,NULL,NULL},
+      /* dummy */
+      {"export-unusable-sigs",0,NULL,NULL},
+      {"export-clean-sigs",0,NULL,NULL},
+      {"export-clean-uids",0,NULL,NULL},
+      {NULL,0,NULL,NULL}
+      /* add tags for include revoked and disabled? */
+    };
+  int rc;
+
+  rc = parse_options (str, options, export_opts, noisy);
+  if (rc && (*options & EXPORT_BACKUP))
+    {
+      /* Alter other options we want or don't want for restore.  */
+      *options |= (EXPORT_LOCAL_SIGS | EXPORT_ATTRIBUTES
+                   | EXPORT_SENSITIVE_REVKEYS);
+      *options &= ~(EXPORT_CLEAN | EXPORT_MINIMAL
+                    | EXPORT_PKA_FORMAT | EXPORT_DANE_FORMAT);
+    }
+  return rc;
+}
+
+
+/* Parse and set an export filter from string.  STRING has the format
+ * "NAME=EXPR" with NAME being the name of the filter.  Spaces before
+ * and after NAME are not allowed.  If this function is called several
+ * times all expressions for the same NAME are concatenated.
+ * Supported filter names are:
+ *
+ *  - keep-uid :: If the expression evaluates to true for a certain
+ *                user ID packet, that packet and all it dependencies
+ *                will be exported.  The expression may use these
+ *                variables:
+ *
+ *                - uid  :: The entire user ID.
+ *                - mbox :: The mail box part of the user ID.
+ *                - primary :: Evaluate to true for the primary user ID.
+ *
+ *  - drop-subkey :: If the expression evaluates to true for a subkey
+ *                packet that subkey and all it dependencies will be
+ *                remove from the keyblock.  The expression may use these
+ *                variables:
+ *
+ *                - secret   :: 1 for a secret subkey, else 0.
+ *                - key_algo :: Public key algorithm id
+ */
+gpg_error_t
+parse_and_set_export_filter (const char *string)
+{
+  gpg_error_t err;
+
+  /* Auto register the cleanup function.  */
+  register_mem_cleanup_func (cleanup_export_globals);
+
+  if (!strncmp (string, "keep-uid=", 9))
+    err = recsel_parse_expr (&export_keep_uid, string+9);
+  else if (!strncmp (string, "drop-subkey=", 12))
+    err = recsel_parse_expr (&export_drop_subkey, string+12);
+  else
+    err = gpg_error (GPG_ERR_INV_NAME);
+
+  return err;
+}
+
+
+/* Push the current export filters onto a stack so that new export
+ * filters can be defined which will be active until the next
+ * pop_export_filters or another push_export_filters.  */
+void
+push_export_filters (void)
+{
+  struct export_filter_attic_s *item;
+
+  item = xcalloc (1, sizeof *item);
+  item->export_keep_uid = export_keep_uid;
+  export_keep_uid = NULL;
+  item->export_drop_subkey = export_drop_subkey;
+  export_drop_subkey = NULL;
+  item->next = export_filter_attic;
+  export_filter_attic = item;
+}
+
+
+/* Revert the last push_export_filters.  */
+void
+pop_export_filters (void)
+{
+  struct export_filter_attic_s *item;
+
+  item = export_filter_attic;
+  if (!item)
+    BUG (); /* No corresponding push.  */
+  export_filter_attic = item->next;
+  cleanup_export_globals ();
+  export_keep_uid = item->export_keep_uid;
+  export_drop_subkey = item->export_drop_subkey;
+}
+
+
+
+/* Create a new export stats object initialized to zero.  On error
+   returns NULL and sets ERRNO.  */
+export_stats_t
+export_new_stats (void)
+{
+  export_stats_t stats;
+
+  return xtrycalloc (1, sizeof *stats);
+}
+
+
+/* Release an export stats object.  */
+void
+export_release_stats (export_stats_t stats)
+{
+  xfree (stats);
+}
+
+
+/* Print export statistics using the status interface.  */
+void
+export_print_stats (export_stats_t stats)
+{
+  if (!stats)
+    return;
+
+  if (is_status_enabled ())
+    {
+      char buf[15*20];
+
+      snprintf (buf, sizeof buf, "%lu %lu %lu",
+		stats->count,
+		stats->secret_count,
+		stats->exported );
+      write_status_text (STATUS_EXPORT_RES, buf);
+    }
+}
+
+
+/*
+ * Export public keys (to stdout or to --output FILE).
+ *
+ * Depending on opt.armor the output is armored.  OPTIONS are defined
+ * in main.h.  If USERS is NULL, all keys will be exported.  STATS is
+ * either an export stats object for update or NULL.
+ *
+ * This function is the core of "gpg --export".
+ */
+int
+export_pubkeys (ctrl_t ctrl, strlist_t users, unsigned int options,
+                export_stats_t stats)
+{
+  return do_export (ctrl, users, 0, options, stats);
+}
+
+
+/*
+ * Export secret keys (to stdout or to --output FILE).
+ *
+ * Depending on opt.armor the output is armored.  OPTIONS are defined
+ * in main.h.  If USERS is NULL, all secret keys will be exported.
+ * STATS is either an export stats object for update or NULL.
+ *
+ * This function is the core of "gpg --export-secret-keys".
+ */
+int
+export_seckeys (ctrl_t ctrl, strlist_t users, unsigned int options,
+                export_stats_t stats)
+{
+  return do_export (ctrl, users, 1, options, stats);
+}
+
+
+/*
+ * Export secret sub keys (to stdout or to --output FILE).
+ *
+ * This is the same as export_seckeys but replaces the primary key by
+ * a stub key.  Depending on opt.armor the output is armored.  OPTIONS
+ * are defined in main.h.  If USERS is NULL, all secret subkeys will
+ * be exported.  STATS is either an export stats object for update or
+ * NULL.
+ *
+ * This function is the core of "gpg --export-secret-subkeys".
+ */
+int
+export_secsubkeys (ctrl_t ctrl, strlist_t users, unsigned int options,
+                   export_stats_t stats)
+{
+  return do_export (ctrl, users, 2, options, stats);
+}
+
+
+/*
+ * Export a single key into a memory buffer.  STATS is either an
+ * export stats object for update or NULL.  If PREFIX is not NULL
+ * PREFIXLEN bytes from PREFIX are prepended to the R_DATA.
+ */
+gpg_error_t
+export_pubkey_buffer (ctrl_t ctrl, const char *keyspec, unsigned int options,
+                      const void *prefix, size_t prefixlen,
+                      export_stats_t stats,
+                      kbnode_t *r_keyblock, void **r_data, size_t *r_datalen)
+{
+  gpg_error_t err;
+  iobuf_t iobuf;
+  int any;
+  strlist_t helplist;
+
+  *r_keyblock = NULL;
+  *r_data = NULL;
+  *r_datalen = 0;
+
+  helplist = NULL;
+  if (!add_to_strlist_try (&helplist, keyspec))
+    return gpg_error_from_syserror ();
+
+  iobuf = iobuf_temp ();
+  if (prefix && prefixlen)
+    iobuf_write (iobuf, prefix, prefixlen);
+  err = do_export_stream (ctrl, iobuf, helplist, 0, r_keyblock, options,
+                          stats, &any);
+  if (!err && !any)
+    err = gpg_error (GPG_ERR_NOT_FOUND);
+  if (!err)
+    {
+      const void *src;
+      size_t datalen;
+
+      iobuf_flush_temp (iobuf);
+      src = iobuf_get_temp_buffer (iobuf);
+      datalen = iobuf_get_temp_length (iobuf);
+      if (!datalen)
+        err = gpg_error (GPG_ERR_NO_PUBKEY);
+      else if (!(*r_data = xtrymalloc (datalen)))
+        err = gpg_error_from_syserror ();
+      else
+        {
+          memcpy (*r_data, src, datalen);
+          *r_datalen = datalen;
+        }
+    }
+  iobuf_close (iobuf);
+  free_strlist (helplist);
+  if (err && *r_keyblock)
+    {
+      release_kbnode (*r_keyblock);
+      *r_keyblock = NULL;
+    }
+  return err;
+}
+
+
+/* Export the keys identified by the list of strings in USERS.  If
+   Secret is false public keys will be exported.  With secret true
+   secret keys will be exported; in this case 1 means the entire
+   secret keyblock and 2 only the subkeys.  OPTIONS are the export
+   options to apply.  */
+static int
+do_export (ctrl_t ctrl, strlist_t users, int secret, unsigned int options,
+           export_stats_t stats)
+{
+  IOBUF out = NULL;
+  int any, rc;
+  armor_filter_context_t *afx = NULL;
+  compress_filter_context_t zfx;
+
+  memset( &zfx, 0, sizeof zfx);
+
+  rc = open_outfile (-1, NULL, 0, !!secret, &out );
+  if (rc)
+    return rc;
+
+  if ( opt.armor && !(options & (EXPORT_PKA_FORMAT|EXPORT_DANE_FORMAT)) )
+    {
+      afx = new_armor_context ();
+      afx->what = secret? 5 : 1;
+      push_armor_filter (afx, out);
+    }
+
+  rc = do_export_stream (ctrl, out, users, secret, NULL, options, stats, &any);
+
+  if ( rc || !any )
+    iobuf_cancel (out);
+  else
+    iobuf_close (out);
+  release_armor_context (afx);
+  return rc;
+}
+
+
+
+/* Release an entire subkey list. */
+static void
+release_subkey_list (subkey_list_t list)
+{
+  while (list)
+    {
+      subkey_list_t tmp = list->next;;
+      xfree (list);
+      list = tmp;
+    }
+}
+
+
+/* Returns true if NODE is a subkey and contained in LIST. */
+static int
+subkey_in_list_p (subkey_list_t list, KBNODE node)
+{
+  if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY
+      || node->pkt->pkttype == PKT_SECRET_SUBKEY )
+    {
+      u32 kid[2];
+
+      keyid_from_pk (node->pkt->pkt.public_key, kid);
+
+      for (; list; list = list->next)
+        if (list->kid[0] == kid[0] && list->kid[1] == kid[1])
+          return 1;
+    }
+  return 0;
+}
+
+/* Allocate a new subkey list item from NODE. */
+static subkey_list_t
+new_subkey_list_item (KBNODE node)
+{
+  subkey_list_t list = xcalloc (1, sizeof *list);
+
+  if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY
+      || node->pkt->pkttype == PKT_SECRET_SUBKEY)
+    keyid_from_pk (node->pkt->pkt.public_key, list->kid);
+
+  return list;
+}
+
+
+/* Helper function to check whether the subkey at NODE actually
+   matches the description at DESC.  The function returns true if the
+   key under question has been specified by an exact specification
+   (keyID or fingerprint) and does match the one at NODE.  It is
+   assumed that the packet at NODE is either a public or secret
+   subkey. */
+int
+exact_subkey_match_p (KEYDB_SEARCH_DESC *desc, kbnode_t node)
+{
+  u32 kid[2];
+  byte fpr[MAX_FINGERPRINT_LEN];
+  size_t fprlen;
+  int result = 0;
+
+  switch(desc->mode)
+    {
+    case KEYDB_SEARCH_MODE_SHORT_KID:
+    case KEYDB_SEARCH_MODE_LONG_KID:
+      keyid_from_pk (node->pkt->pkt.public_key, kid);
+      break;
+
+    case KEYDB_SEARCH_MODE_FPR16:
+    case KEYDB_SEARCH_MODE_FPR20:
+    case KEYDB_SEARCH_MODE_FPR:
+      fingerprint_from_pk (node->pkt->pkt.public_key, fpr,&fprlen);
+      break;
+
+    default:
+      break;
+    }
+
+  switch(desc->mode)
+    {
+    case KEYDB_SEARCH_MODE_SHORT_KID:
+      if (desc->u.kid[1] == kid[1])
+        result = 1;
+      break;
+
+    case KEYDB_SEARCH_MODE_LONG_KID:
+      if (desc->u.kid[0] == kid[0] && desc->u.kid[1] == kid[1])
+        result = 1;
+      break;
+
+    case KEYDB_SEARCH_MODE_FPR16:
+      if (!memcmp (desc->u.fpr, fpr, 16))
+        result = 1;
+      break;
+
+    case KEYDB_SEARCH_MODE_FPR20:
+    case KEYDB_SEARCH_MODE_FPR:
+      if (!memcmp (desc->u.fpr, fpr, 20))
+        result = 1;
+      break;
+
+    default:
+      break;
+    }
+
+  return result;
+}
+
+
+/* Return an error if the key represented by the S-expression S_KEY
+ * and the OpenPGP key represented by PK do not use the same curve. */
+static gpg_error_t
+match_curve_skey_pk (gcry_sexp_t s_key, PKT_public_key *pk)
+{
+  gcry_sexp_t curve = NULL;
+  gcry_sexp_t flags = NULL;
+  char *curve_str = NULL;
+  char *flag;
+  const char *oidstr = NULL;
+  gcry_mpi_t curve_as_mpi = NULL;
+  gpg_error_t err;
+  int is_eddsa = 0;
+  int idx = 0;
+
+  if (!(pk->pubkey_algo==PUBKEY_ALGO_ECDH
+        || pk->pubkey_algo==PUBKEY_ALGO_ECDSA
+        || pk->pubkey_algo==PUBKEY_ALGO_EDDSA))
+    return gpg_error (GPG_ERR_PUBKEY_ALGO);
+
+  curve = gcry_sexp_find_token (s_key, "curve", 0);
+  if (!curve)
+    {
+      log_error ("no reported curve\n");
+      return gpg_error (GPG_ERR_UNKNOWN_CURVE);
+    }
+  curve_str = gcry_sexp_nth_string (curve, 1);
+  gcry_sexp_release (curve); curve = NULL;
+  if (!curve_str)
+    {
+      log_error ("no curve name\n");
+      return gpg_error (GPG_ERR_UNKNOWN_CURVE);
+    }
+  oidstr = openpgp_curve_to_oid (curve_str, NULL, NULL);
+  if (!oidstr)
+    {
+      log_error ("no OID known for curve '%s'\n", curve_str);
+      xfree (curve_str);
+      return gpg_error (GPG_ERR_UNKNOWN_CURVE);
+    }
+  xfree (curve_str);
+  err = openpgp_oid_from_str (oidstr, &curve_as_mpi);
+  if (err)
+    return err;
+  if (gcry_mpi_cmp (pk->pkey[0], curve_as_mpi))
+    {
+      log_error ("curves do not match\n");
+      gcry_mpi_release (curve_as_mpi);
+      return gpg_error (GPG_ERR_INV_CURVE);
+    }
+  gcry_mpi_release (curve_as_mpi);
+  flags = gcry_sexp_find_token (s_key, "flags", 0);
+  if (flags)
+    {
+      for (idx = 1; idx < gcry_sexp_length (flags); idx++)
+        {
+          flag = gcry_sexp_nth_string (flags, idx);
+          if (flag && (strcmp ("eddsa", flag) == 0))
+            is_eddsa = 1;
+          gcry_free (flag);
+        }
+    }
+  if (is_eddsa != (pk->pubkey_algo == PUBKEY_ALGO_EDDSA))
+    {
+      log_error ("disagreement about EdDSA\n");
+      err = gpg_error (GPG_ERR_INV_CURVE);
+    }
+
+  return err;
+}
+
+
+/* Return a canonicalized public key algoithms.  This is used to
+   compare different flavors of algorithms (e.g. ELG and ELG_E are
+   considered the same).  */
+static enum gcry_pk_algos
+canon_pk_algo (enum gcry_pk_algos algo)
+{
+  switch (algo)
+    {
+    case GCRY_PK_RSA:
+    case GCRY_PK_RSA_E:
+    case GCRY_PK_RSA_S: return GCRY_PK_RSA;
+    case GCRY_PK_ELG:
+    case GCRY_PK_ELG_E: return GCRY_PK_ELG;
+    case GCRY_PK_ECC:
+    case GCRY_PK_ECDSA:
+    case GCRY_PK_ECDH: return GCRY_PK_ECC;
+    default: return algo;
+    }
+}
+
+
+/* Take a cleartext dump of a secret key in PK and change the
+ * parameter array in PK to include the secret parameters.  */
+static gpg_error_t
+cleartext_secret_key_to_openpgp (gcry_sexp_t s_key, PKT_public_key *pk)
+{
+  gpg_error_t err;
+  gcry_sexp_t top_list;
+  gcry_sexp_t key = NULL;
+  char *key_type = NULL;
+  enum gcry_pk_algos pk_algo;
+  struct seckey_info *ski;
+  int idx, sec_start;
+  gcry_mpi_t pub_params[10] = { NULL };
+
+  /* we look for a private-key, then the first element in it tells us
+     the type */
+  top_list = gcry_sexp_find_token (s_key, "private-key", 0);
+  if (!top_list)
+    goto bad_seckey;
+
+  /* ignore all S-expression after the first sublist -- we assume that
+     they are comments or otherwise irrelevant to OpenPGP */
+  if (gcry_sexp_length(top_list) < 2)
+    goto bad_seckey;
+  key = gcry_sexp_nth (top_list, 1);
+  if (!key)
+    goto bad_seckey;
+  key_type = gcry_sexp_nth_string(key, 0);
+  pk_algo = gcry_pk_map_name (key_type);
+
+  log_assert (!pk->seckey_info);
+
+  pk->seckey_info = ski = xtrycalloc (1, sizeof *ski);
+  if (!ski)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+
+  switch (canon_pk_algo (pk_algo))
+    {
+    case GCRY_PK_RSA:
+      if (!is_RSA (pk->pubkey_algo))
+        goto bad_pubkey_algo;
+      err = gcry_sexp_extract_param (key, NULL, "ne",
+                                     &pub_params[0],
+                                     &pub_params[1],
+                                     NULL);
+      for (idx=0; idx < 2 && !err; idx++)
+        if (gcry_mpi_cmp(pk->pkey[idx], pub_params[idx]))
+          err = gpg_error (GPG_ERR_BAD_PUBKEY);
+      if (!err)
+        {
+          for (idx = 2; idx < 6 && !err; idx++)
+            {
+              gcry_mpi_release (pk->pkey[idx]);
+              pk->pkey[idx] = NULL;
+            }
+          err = gcry_sexp_extract_param (key, NULL, "dpqu",
+                                         &pk->pkey[2],
+                                         &pk->pkey[3],
+                                         &pk->pkey[4],
+                                         &pk->pkey[5],
+                                         NULL);
+        }
+      if (!err)
+        {
+          for (idx = 2; idx < 6; idx++)
+            ski->csum += checksum_mpi (pk->pkey[idx]);
+        }
+      break;
+
+    case GCRY_PK_DSA:
+      if (!is_DSA (pk->pubkey_algo))
+        goto bad_pubkey_algo;
+      err = gcry_sexp_extract_param (key, NULL, "pqgy",
+                                     &pub_params[0],
+                                     &pub_params[1],
+                                     &pub_params[2],
+                                     &pub_params[3],
+                                     NULL);
+      for (idx=0; idx < 4 && !err; idx++)
+        if (gcry_mpi_cmp(pk->pkey[idx], pub_params[idx]))
+          err = gpg_error (GPG_ERR_BAD_PUBKEY);
+      if (!err)
+        {
+          gcry_mpi_release (pk->pkey[4]);
+          pk->pkey[4] = NULL;
+          err = gcry_sexp_extract_param (key, NULL, "x",
+                                         &pk->pkey[4],
+                                         NULL);
+        }
+      if (!err)
+        ski->csum += checksum_mpi (pk->pkey[4]);
+      break;
+
+    case GCRY_PK_ELG:
+      if (!is_ELGAMAL (pk->pubkey_algo))
+        goto bad_pubkey_algo;
+      err = gcry_sexp_extract_param (key, NULL, "pgy",
+                                     &pub_params[0],
+                                     &pub_params[1],
+                                     &pub_params[2],
+                                     NULL);
+      for (idx=0; idx < 3 && !err; idx++)
+        if (gcry_mpi_cmp(pk->pkey[idx], pub_params[idx]))
+          err = gpg_error (GPG_ERR_BAD_PUBKEY);
+      if (!err)
+        {
+          gcry_mpi_release (pk->pkey[3]);
+          pk->pkey[3] = NULL;
+          err = gcry_sexp_extract_param (key, NULL, "x",
+                                         &pk->pkey[3],
+                                         NULL);
+        }
+      if (!err)
+        ski->csum += checksum_mpi (pk->pkey[3]);
+      break;
+
+    case GCRY_PK_ECC:
+      err = match_curve_skey_pk (key, pk);
+      if (err)
+        goto leave;
+      if (!err)
+        err = gcry_sexp_extract_param (key, NULL, "q",
+                                       &pub_params[0],
+                                       NULL);
+      if (!err && (gcry_mpi_cmp(pk->pkey[1], pub_params[0])))
+        err = gpg_error (GPG_ERR_BAD_PUBKEY);
+
+      sec_start = 2;
+      if (pk->pubkey_algo == PUBKEY_ALGO_ECDH)
+        sec_start += 1;
+      if (!err)
+        {
+          gcry_mpi_release (pk->pkey[sec_start]);
+          pk->pkey[sec_start] = NULL;
+          err = gcry_sexp_extract_param (key, NULL, "d",
+                                         &pk->pkey[sec_start],
+                                         NULL);
+        }
+
+      if (!err)
+        ski->csum += checksum_mpi (pk->pkey[sec_start]);
+      break;
+
+    default:
+      pk->seckey_info = NULL;
+      xfree (ski);
+      err = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+      break;
+    }
+
+ leave:
+  gcry_sexp_release (top_list);
+  gcry_sexp_release (key);
+  gcry_free (key_type);
+
+  for (idx=0; idx < DIM(pub_params); idx++)
+    gcry_mpi_release (pub_params[idx]);
+  return err;
+
+ bad_pubkey_algo:
+  err = gpg_error (GPG_ERR_PUBKEY_ALGO);
+  goto leave;
+
+ bad_seckey:
+  err = gpg_error (GPG_ERR_BAD_SECKEY);
+  goto leave;
+}
+
+
+/* Use the key transfer format given in S_PGP to create the secinfo
+   structure in PK and change the parameter array in PK to include the
+   secret parameters.  */
+static gpg_error_t
+transfer_format_to_openpgp (gcry_sexp_t s_pgp, PKT_public_key *pk)
+{
+  gpg_error_t err;
+  gcry_sexp_t top_list;
+  gcry_sexp_t list = NULL;
+  char *curve = NULL;
+  const char *value;
+  size_t valuelen;
+  char *string;
+  int  idx;
+  int  is_v4, is_protected;
+  enum gcry_pk_algos pk_algo;
+  int  protect_algo = 0;
+  char iv[16];
+  int  ivlen = 0;
+  int  s2k_mode = 0;
+  int  s2k_algo = 0;
+  byte s2k_salt[8];
+  u32  s2k_count = 0;
+  int  is_ecdh = 0;
+  size_t npkey, nskey;
+  gcry_mpi_t skey[10];  /* We support up to 9 parameters.  */
+  int skeyidx = 0;
+  struct seckey_info *ski;
+
+  /* gcry_log_debugsxp ("transferkey", s_pgp); */
+  top_list = gcry_sexp_find_token (s_pgp, "openpgp-private-key", 0);
+  if (!top_list)
+    goto bad_seckey;
+
+  list = gcry_sexp_find_token (top_list, "version", 0);
+  if (!list)
+    goto bad_seckey;
+  value = gcry_sexp_nth_data (list, 1, &valuelen);
+  if (!value || valuelen != 1 || !(value[0] == '3' || value[0] == '4'))
+    goto bad_seckey;
+  is_v4 = (value[0] == '4');
+
+  gcry_sexp_release (list);
+  list = gcry_sexp_find_token (top_list, "protection", 0);
+  if (!list)
+    goto bad_seckey;
+  value = gcry_sexp_nth_data (list, 1, &valuelen);
+  if (!value)
+    goto bad_seckey;
+  if (valuelen == 4 && !memcmp (value, "sha1", 4))
+    is_protected = 2;
+  else if (valuelen == 3 && !memcmp (value, "sum", 3))
+    is_protected = 1;
+  else if (valuelen == 4 && !memcmp (value, "none", 4))
+    is_protected = 0;
+  else
+    goto bad_seckey;
+  if (is_protected)
+    {
+      string = gcry_sexp_nth_string (list, 2);
+      if (!string)
+        goto bad_seckey;
+      protect_algo = gcry_cipher_map_name (string);
+      xfree (string);
+
+      value = gcry_sexp_nth_data (list, 3, &valuelen);
+      if (!value || !valuelen || valuelen > sizeof iv)
+        goto bad_seckey;
+      memcpy (iv, value, valuelen);
+      ivlen = valuelen;
+
+      string = gcry_sexp_nth_string (list, 4);
+      if (!string)
+        goto bad_seckey;
+      s2k_mode = strtol (string, NULL, 10);
+      xfree (string);
+
+      string = gcry_sexp_nth_string (list, 5);
+      if (!string)
+        goto bad_seckey;
+      s2k_algo = gcry_md_map_name (string);
+      xfree (string);
+
+      value = gcry_sexp_nth_data (list, 6, &valuelen);
+      if (!value || !valuelen || valuelen > sizeof s2k_salt)
+        goto bad_seckey;
+      memcpy (s2k_salt, value, valuelen);
+
+      string = gcry_sexp_nth_string (list, 7);
+      if (!string)
+        goto bad_seckey;
+      s2k_count = strtoul (string, NULL, 10);
+      xfree (string);
+    }
+
+  /* Parse the gcrypt PK algo and check that it is okay.  */
+  gcry_sexp_release (list);
+  list = gcry_sexp_find_token (top_list, "algo", 0);
+  if (!list)
+    goto bad_seckey;
+  string = gcry_sexp_nth_string (list, 1);
+  if (!string)
+    goto bad_seckey;
+  pk_algo = gcry_pk_map_name (string);
+  xfree (string); string = NULL;
+  if (gcry_pk_algo_info (pk_algo, GCRYCTL_GET_ALGO_NPKEY, NULL, &npkey)
+      || gcry_pk_algo_info (pk_algo, GCRYCTL_GET_ALGO_NSKEY, NULL, &nskey)
+      || !npkey || npkey >= nskey)
+    goto bad_seckey;
+
+  /* Check that the pubkey algo matches the one from the public key.  */
+  switch (canon_pk_algo (pk_algo))
+    {
+    case GCRY_PK_RSA:
+      if (!is_RSA (pk->pubkey_algo))
+        pk_algo = 0;  /* Does not match.  */
+      break;
+    case GCRY_PK_DSA:
+      if (!is_DSA (pk->pubkey_algo))
+        pk_algo = 0;  /* Does not match.  */
+      break;
+    case GCRY_PK_ELG:
+      if (!is_ELGAMAL (pk->pubkey_algo))
+        pk_algo = 0;  /* Does not match.  */
+      break;
+    case GCRY_PK_ECC:
+      if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA)
+        ;
+      else if (pk->pubkey_algo == PUBKEY_ALGO_ECDH)
+        is_ecdh = 1;
+      else if (pk->pubkey_algo == PUBKEY_ALGO_EDDSA)
+        ;
+      else
+        pk_algo = 0;  /* Does not match.  */
+      /* For ECC we do not have the domain parameters thus fix our info.  */
+      npkey = 1;
+      nskey = 2;
+      break;
+    default:
+      pk_algo = 0;   /* Oops.  */
+      break;
+    }
+  if (!pk_algo)
+    {
+      err = gpg_error (GPG_ERR_PUBKEY_ALGO);
+      goto leave;
+    }
+
+  /* This check has to go after the ecc adjustments. */
+  if (nskey > PUBKEY_MAX_NSKEY)
+    goto bad_seckey;
+
+  /* Parse the key parameters.  */
+  gcry_sexp_release (list);
+  list = gcry_sexp_find_token (top_list, "skey", 0);
+  if (!list)
+    goto bad_seckey;
+  for (idx=0;;)
+    {
+      int is_enc;
+
+      value = gcry_sexp_nth_data (list, ++idx, &valuelen);
+      if (!value && skeyidx >= npkey)
+        break;  /* Ready.  */
+
+      /* Check for too many parameters.  Note that depending on the
+         protection mode and version number we may see less than NSKEY
+         (but at least NPKEY+1) parameters.  */
+      if (idx >= 2*nskey)
+        goto bad_seckey;
+      if (skeyidx >= DIM (skey)-1)
+        goto bad_seckey;
+
+      if (!value || valuelen != 1 || !(value[0] == '_' || value[0] == 'e'))
+        goto bad_seckey;
+      is_enc = (value[0] == 'e');
+      value = gcry_sexp_nth_data (list, ++idx, &valuelen);
+      if (!value || !valuelen)
+        goto bad_seckey;
+      if (is_enc)
+        {
+          void *p = xtrymalloc (valuelen);
+          if (!p)
+            goto outofmem;
+          memcpy (p, value, valuelen);
+          skey[skeyidx] = gcry_mpi_set_opaque (NULL, p, valuelen*8);
+          if (!skey[skeyidx])
+            goto outofmem;
+        }
+      else
+        {
+          if (gcry_mpi_scan (skey + skeyidx, GCRYMPI_FMT_STD,
+                             value, valuelen, NULL))
+            goto bad_seckey;
+        }
+      skeyidx++;
+    }
+  skey[skeyidx++] = NULL;
+
+  gcry_sexp_release (list); list = NULL;
+
+  /* We have no need for the CSUM value thus we don't parse it.  */
+  /* list = gcry_sexp_find_token (top_list, "csum", 0); */
+  /* if (list) */
+  /*   { */
+  /*     string = gcry_sexp_nth_string (list, 1); */
+  /*     if (!string) */
+  /*       goto bad_seckey; */
+  /*     desired_csum = strtoul (string, NULL, 10); */
+  /*     xfree (string); */
+  /*   } */
+  /* else */
+  /*   desired_csum = 0; */
+  /* gcry_sexp_release (list); list = NULL; */
+
+  /* Get the curve name if any,  */
+  list = gcry_sexp_find_token (top_list, "curve", 0);
+  if (list)
+    {
+      curve = gcry_sexp_nth_string (list, 1);
+      gcry_sexp_release (list); list = NULL;
+    }
+
+  gcry_sexp_release (top_list); top_list = NULL;
+
+  /* log_debug ("XXX is_v4=%d\n", is_v4); */
+  /* log_debug ("XXX pubkey_algo=%d\n", pubkey_algo); */
+  /* log_debug ("XXX is_protected=%d\n", is_protected); */
+  /* log_debug ("XXX protect_algo=%d\n", protect_algo); */
+  /* log_printhex (iv, ivlen, "XXX iv"); */
+  /* log_debug ("XXX ivlen=%d\n", ivlen); */
+  /* log_debug ("XXX s2k_mode=%d\n", s2k_mode); */
+  /* log_debug ("XXX s2k_algo=%d\n", s2k_algo); */
+  /* log_printhex (s2k_salt, sizeof s2k_salt, "XXX s2k_salt"); */
+  /* log_debug ("XXX s2k_count=%lu\n", (unsigned long)s2k_count); */
+  /* for (idx=0; skey[idx]; idx++) */
+  /*   { */
+  /*     int is_enc = gcry_mpi_get_flag (skey[idx], GCRYMPI_FLAG_OPAQUE); */
+  /*     log_info ("XXX skey[%d]%s:", idx, is_enc? " (enc)":""); */
+  /*     if (is_enc) */
+  /*       { */
+  /*         void *p; */
+  /*         unsigned int nbits; */
+  /*         p = gcry_mpi_get_opaque (skey[idx], &nbits); */
+  /*         log_printhex ( p, (nbits+7)/8, NULL); */
+  /*       } */
+  /*     else */
+  /*       gcry_mpi_dump (skey[idx]); */
+  /*     log_printf ("\n"); */
+  /*   } */
+
+  if (!is_v4 || is_protected != 2 )
+    {
+      /* We only support the v4 format and a SHA-1 checksum.  */
+      err = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+      goto leave;
+    }
+
+  /* We need to change the received parameters for ECC algorithms.
+     The transfer format has the curve name and the parameters
+     separate.  We put them all into the SKEY array.  */
+  if (canon_pk_algo (pk_algo) == GCRY_PK_ECC)
+    {
+      const char *oidstr;
+
+      /* Assert that all required parameters are available.  We also
+         check that the array does not contain more parameters than
+         needed (this was used by some beta versions of 2.1.  */
+      if (!curve || !skey[0] || !skey[1] || skey[2])
+        {
+          err = gpg_error (GPG_ERR_INTERNAL);
+          goto leave;
+        }
+
+      oidstr = openpgp_curve_to_oid (curve, NULL, NULL);
+      if (!oidstr)
+        {
+          log_error ("no OID known for curve '%s'\n", curve);
+          err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
+          goto leave;
+        }
+      /* Put the curve's OID into the MPI array.  This requires
+         that we shift Q and D.  For ECDH also insert the KDF parms. */
+      if (is_ecdh)
+        {
+          skey[4] = NULL;
+          skey[3] = skey[1];
+          skey[2] = gcry_mpi_copy (pk->pkey[2]);
+        }
+      else
+        {
+          skey[3] = NULL;
+          skey[2] = skey[1];
+        }
+      skey[1] = skey[0];
+      skey[0] = NULL;
+      err = openpgp_oid_from_str (oidstr, skey + 0);
+      if (err)
+        goto leave;
+      /* Fixup the NPKEY and NSKEY to match OpenPGP reality.  */
+      npkey = 2 + is_ecdh;
+      nskey = 3 + is_ecdh;
+
+      /* for (idx=0; skey[idx]; idx++) */
+      /*   { */
+      /*     log_info ("YYY skey[%d]:", idx); */
+      /*     if (gcry_mpi_get_flag (skey[idx], GCRYMPI_FLAG_OPAQUE)) */
+      /*       { */
+      /*         void *p; */
+      /*         unsigned int nbits; */
+      /*         p = gcry_mpi_get_opaque (skey[idx], &nbits); */
+      /*         log_printhex (p, (nbits+7)/8, NULL); */
+      /*       } */
+      /*     else */
+      /*       gcry_mpi_dump (skey[idx]); */
+      /*     log_printf ("\n"); */
+      /*   } */
+    }
+
+  /* Do some sanity checks.  */
+  if (s2k_count > 255)
+    {
+      /* We expect an already encoded S2K count.  */
+      err = gpg_error (GPG_ERR_INV_DATA);
+      goto leave;
+    }
+  err = openpgp_cipher_test_algo (protect_algo);
+  if (err)
+    goto leave;
+  err = openpgp_md_test_algo (s2k_algo);
+  if (err)
+    goto leave;
+
+  /* Check that the public key parameters match.  Note that since
+     Libgcrypt 1.5 gcry_mpi_cmp handles opaque MPI correctly.  */
+  for (idx=0; idx < npkey; idx++)
+    if (gcry_mpi_cmp (pk->pkey[idx], skey[idx]))
+      {
+        err = gpg_error (GPG_ERR_BAD_PUBKEY);
+        goto leave;
+      }
+
+  /* Check that the first secret key parameter in SKEY is encrypted
+     and that there are no more secret key parameters.  The latter is
+     guaranteed by the v4 packet format.  */
+  if (!gcry_mpi_get_flag (skey[npkey], GCRYMPI_FLAG_OPAQUE))
+    goto bad_seckey;
+  if (npkey+1 < DIM (skey) && skey[npkey+1])
+    goto bad_seckey;
+
+  /* Check that the secret key parameters in PK are all set to NULL. */
+  for (idx=npkey; idx < nskey; idx++)
+    if (pk->pkey[idx])
+      goto bad_seckey;
+
+  /* Now build the protection info. */
+  pk->seckey_info = ski = xtrycalloc (1, sizeof *ski);
+  if (!ski)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+
+  ski->is_protected = 1;
+  ski->sha1chk = 1;
+  ski->algo = protect_algo;
+  ski->s2k.mode = s2k_mode;
+  ski->s2k.hash_algo = s2k_algo;
+  log_assert (sizeof ski->s2k.salt == sizeof s2k_salt);
+  memcpy (ski->s2k.salt, s2k_salt, sizeof s2k_salt);
+  ski->s2k.count = s2k_count;
+  log_assert (ivlen <= sizeof ski->iv);
+  memcpy (ski->iv, iv, ivlen);
+  ski->ivlen = ivlen;
+
+  /* Store the protected secret key parameter.  */
+  pk->pkey[npkey] = skey[npkey];
+  skey[npkey] = NULL;
+
+  /* That's it.  */
+
+ leave:
+  gcry_free (curve);
+  gcry_sexp_release (list);
+  gcry_sexp_release (top_list);
+  for (idx=0; idx < skeyidx; idx++)
+    gcry_mpi_release (skey[idx]);
+  return err;
+
+ bad_seckey:
+  err = gpg_error (GPG_ERR_BAD_SECKEY);
+  goto leave;
+
+ outofmem:
+  err = gpg_error (GPG_ERR_ENOMEM);
+  goto leave;
+}
+
+
+/* Print an "EXPORTED" status line.  PK is the primary public key.  */
+static void
+print_status_exported (PKT_public_key *pk)
+{
+  char *hexfpr;
+
+  if (!is_status_enabled ())
+    return;
+
+  hexfpr = hexfingerprint (pk, NULL, 0);
+  write_status_text (STATUS_EXPORTED, hexfpr? hexfpr : "[?]");
+  xfree (hexfpr);
+}
+
+
+/*
+ * Receive a secret key from agent specified by HEXGRIP.
+ *
+ * Since the key data from the agent is encrypted, decrypt it using
+ * CIPHERHD context.  Then, parse the decrypted key data into transfer
+ * format, and put secret parameters into PK.
+ *
+ * If CLEARTEXT is 0, store the secret key material
+ * passphrase-protected.  Otherwise, store secret key material in the
+ * clear.
+ *
+ * CACHE_NONCE_ADDR is used to share nonce for multple key retrievals.
+ */
+gpg_error_t
+receive_seckey_from_agent (ctrl_t ctrl, gcry_cipher_hd_t cipherhd,
+                           int cleartext,
+                           char **cache_nonce_addr, const char *hexgrip,
+                           PKT_public_key *pk)
+{
+  gpg_error_t err = 0;
+  unsigned char *wrappedkey = NULL;
+  size_t wrappedkeylen;
+  unsigned char *key = NULL;
+  size_t keylen, realkeylen;
+  gcry_sexp_t s_skey;
+  char *prompt;
+
+  if (opt.verbose)
+    log_info ("key %s: asking agent for the secret parts\n", hexgrip);
+
+  prompt = gpg_format_keydesc (ctrl, pk, FORMAT_KEYDESC_EXPORT,1);
+  err = agent_export_key (ctrl, hexgrip, prompt, !cleartext, cache_nonce_addr,
+                          &wrappedkey, &wrappedkeylen,
+			  pk->keyid, pk->main_keyid, pk->pubkey_algo);
+  xfree (prompt);
+
+  if (err)
+    goto unwraperror;
+  if (wrappedkeylen < 24)
+    {
+      err = gpg_error (GPG_ERR_INV_LENGTH);
+      goto unwraperror;
+    }
+  keylen = wrappedkeylen - 8;
+  key = xtrymalloc_secure (keylen);
+  if (!key)
+    {
+      err = gpg_error_from_syserror ();
+      goto unwraperror;
+    }
+  err = gcry_cipher_decrypt (cipherhd, key, keylen, wrappedkey, wrappedkeylen);
+  if (err)
+    goto unwraperror;
+  realkeylen = gcry_sexp_canon_len (key, keylen, NULL, &err);
+  if (!realkeylen)
+    goto unwraperror; /* Invalid csexp.  */
+
+  err = gcry_sexp_sscan (&s_skey, NULL, key, realkeylen);
+  if (!err)
+    {
+      if (cleartext)
+        err = cleartext_secret_key_to_openpgp (s_skey, pk);
+      else
+        err = transfer_format_to_openpgp (s_skey, pk);
+      gcry_sexp_release (s_skey);
+    }
+
+ unwraperror:
+  xfree (key);
+  xfree (wrappedkey);
+  if (err)
+    {
+      log_error ("key %s: error receiving key from agent:"
+                 " %s%s\n", hexgrip, gpg_strerror (err),
+                 gpg_err_code (err) == GPG_ERR_FULLY_CANCELED?
+                 "":_(" - skipped"));
+    }
+  return err;
+}
+
+
+/* Write KEYBLOCK either to stdout or to the file set with the
+ * --output option.  This is a simplified version of do_export_stream
+ * which supports only a few export options.  */
+gpg_error_t
+write_keyblock_to_output (kbnode_t keyblock, int with_armor,
+                          unsigned int options)
+{
+  gpg_error_t err;
+  const char *fname;
+  iobuf_t out;
+  kbnode_t node;
+  armor_filter_context_t *afx = NULL;
+  iobuf_t out_help = NULL;
+  PKT_public_key *pk = NULL;
+
+  fname = opt.outfile? opt.outfile : "-";
+  if (is_secured_filename (fname) )
+    return gpg_error (GPG_ERR_EPERM);
+
+  out = iobuf_create (fname, 0);
+  if (!out)
+    {
+      err = gpg_error_from_syserror ();
+      log_error(_("can't create '%s': %s\n"), fname, gpg_strerror (err));
+      return err;
+    }
+  if (opt.verbose)
+    log_info (_("writing to '%s'\n"), iobuf_get_fname_nonnull (out));
+
+  if ((options & (EXPORT_PKA_FORMAT|EXPORT_DANE_FORMAT)))
+    {
+      with_armor = 0;
+      out_help = iobuf_temp ();
+    }
+
+  if (with_armor)
+    {
+      afx = new_armor_context ();
+      afx->what = 1;
+      push_armor_filter (afx, out);
+    }
+
+  for (node = keyblock; node; node = node->next)
+    {
+      if (is_deleted_kbnode (node))
+        continue;
+      if (node->pkt->pkttype == PKT_RING_TRUST)
+        continue; /* Skip - they should not be here anyway.  */
+
+      if (!pk && (node->pkt->pkttype == PKT_PUBLIC_KEY
+                  || node->pkt->pkttype == PKT_SECRET_KEY))
+        pk = node->pkt->pkt.public_key;
+
+      if ((options & EXPORT_BACKUP))
+        err = build_packet_and_meta (out_help? out_help : out, node->pkt);
+      else
+        err = build_packet (out_help? out_help : out, node->pkt);
+      if (err)
+        {
+          log_error ("build_packet(%d) failed: %s\n",
+                     node->pkt->pkttype, gpg_strerror (err) );
+          goto leave;
+        }
+    }
+  err = 0;
+
+  if (out_help && pk)
+    {
+      const void *data;
+      size_t datalen;
+
+      iobuf_flush_temp (out_help);
+      data = iobuf_get_temp_buffer (out_help);
+      datalen = iobuf_get_temp_length (out_help);
+
+      err = print_pka_or_dane_records (out,
+                                       keyblock, pk, data, datalen,
+                                       (options & EXPORT_PKA_FORMAT),
+                                       (options & EXPORT_DANE_FORMAT));
+    }
+
+ leave:
+  if (err)
+    iobuf_cancel (out);
+  else
+    iobuf_close (out);
+  iobuf_cancel (out_help);
+  release_armor_context (afx);
+  return err;
+}
+
+
+/*
+ * Apply the keep-uid filter to the keyblock.  The deleted nodes are
+ * marked and thus the caller should call commit_kbnode afterwards.
+ * KEYBLOCK must not have any blocks marked as deleted.
+ */
+static void
+apply_keep_uid_filter (ctrl_t ctrl, kbnode_t keyblock, recsel_expr_t selector)
+{
+  kbnode_t node;
+  struct impex_filter_parm_s parm;
+
+  parm.ctrl = ctrl;
+
+  for (node = keyblock->next; node; node = node->next )
+    {
+      if (node->pkt->pkttype == PKT_USER_ID)
+        {
+          parm.node = node;
+          if (!recsel_select (selector, impex_filter_getval, &parm))
+            {
+              /* log_debug ("keep-uid: deleting '%s'\n", */
+              /*            node->pkt->pkt.user_id->name); */
+              /* The UID packet and all following packets up to the
+               * next UID or a subkey.  */
+              delete_kbnode (node);
+              for (; node->next
+                     && node->next->pkt->pkttype != PKT_USER_ID
+                     && node->next->pkt->pkttype != PKT_PUBLIC_SUBKEY
+                     && node->next->pkt->pkttype != PKT_SECRET_SUBKEY ;
+                   node = node->next)
+                delete_kbnode (node->next);
+	    }
+          /* else */
+          /*   log_debug ("keep-uid: keeping '%s'\n", */
+          /*              node->pkt->pkt.user_id->name); */
+        }
+    }
+}
+
+
+/*
+ * Apply the drop-subkey filter to the keyblock.  The deleted nodes are
+ * marked and thus the caller should call commit_kbnode afterwards.
+ * KEYBLOCK must not have any blocks marked as deleted.
+ */
+static void
+apply_drop_subkey_filter (ctrl_t ctrl, kbnode_t keyblock,
+                          recsel_expr_t selector)
+{
+  kbnode_t node;
+  struct impex_filter_parm_s parm;
+
+  parm.ctrl = ctrl;
+
+  for (node = keyblock->next; node; node = node->next )
+    {
+      if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY
+          || node->pkt->pkttype == PKT_SECRET_SUBKEY)
+        {
+          parm.node = node;
+          if (recsel_select (selector, impex_filter_getval, &parm))
+            {
+              /*log_debug ("drop-subkey: deleting a key\n");*/
+              /* The subkey packet and all following packets up to the
+               * next subkey.  */
+              delete_kbnode (node);
+              for (; node->next
+                     && node->next->pkt->pkttype != PKT_PUBLIC_SUBKEY
+                     && node->next->pkt->pkttype != PKT_SECRET_SUBKEY ;
+                   node = node->next)
+                delete_kbnode (node->next);
+	    }
+        }
+    }
+}
+
+
+/* Print DANE or PKA records for all user IDs in KEYBLOCK to OUT.  The
+ * data for the record is taken from (DATA,DATELEN).  PK is the public
+ * key packet with the primary key. */
+static gpg_error_t
+print_pka_or_dane_records (iobuf_t out, kbnode_t keyblock, PKT_public_key *pk,
+                           const void *data, size_t datalen,
+                           int print_pka, int print_dane)
+{
+  gpg_error_t err = 0;
+  kbnode_t kbctx, node;
+  PKT_user_id *uid;
+  char *mbox = NULL;
+  char hashbuf[32];
+  char *hash = NULL;
+  char *domain;
+  const char *s;
+  unsigned int len;
+  estream_t fp = NULL;
+  char *hexdata = NULL;
+  char *hexfpr;
+
+  hexfpr = hexfingerprint (pk, NULL, 0);
+  if (!hexfpr)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+  hexdata = bin2hex (data, datalen, NULL);
+  if (!hexdata)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+  ascii_strlwr (hexdata);
+  fp = es_fopenmem (0, "rw,samethread");
+  if (!fp)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+
+  for (kbctx = NULL; (node = walk_kbnode (keyblock, &kbctx, 0));)
+    {
+      if (node->pkt->pkttype != PKT_USER_ID)
+        continue;
+      uid = node->pkt->pkt.user_id;
+
+      if (uid->flags.expired || uid->flags.revoked)
+        continue;
+
+      xfree (mbox);
+      mbox = mailbox_from_userid (uid->name);
+      if (!mbox)
+        continue;
+
+      domain = strchr (mbox, '@');
+      *domain++ = 0;
+
+      if (print_pka)
+        {
+          es_fprintf (fp, "$ORIGIN _pka.%s.\n; %s\n; ", domain, hexfpr);
+          print_utf8_buffer (fp, uid->name, uid->len);
+          es_putc ('\n', fp);
+          gcry_md_hash_buffer (GCRY_MD_SHA1, hashbuf, mbox, strlen (mbox));
+          xfree (hash);
+          hash = zb32_encode (hashbuf, 8*20);
+          if (!hash)
+            {
+              err = gpg_error_from_syserror ();
+              goto leave;
+            }
+          len = strlen (hexfpr)/2;
+          es_fprintf (fp, "%s TYPE37 \\# %u 0006 0000 00 %02X %s\n\n",
+                      hash, 6 + len, len, hexfpr);
+        }
+
+      if (print_dane && hexdata)
+        {
+          es_fprintf (fp, "$ORIGIN _openpgpkey.%s.\n; %s\n; ", domain, hexfpr);
+          print_utf8_buffer (fp, uid->name, uid->len);
+          es_putc ('\n', fp);
+          gcry_md_hash_buffer (GCRY_MD_SHA256, hashbuf, mbox, strlen (mbox));
+          xfree (hash);
+          hash = bin2hex (hashbuf, 28, NULL);
+          if (!hash)
+            {
+              err = gpg_error_from_syserror ();
+              goto leave;
+            }
+          ascii_strlwr (hash);
+          len = strlen (hexdata)/2;
+          es_fprintf (fp, "%s TYPE61 \\# %u (\n", hash, len);
+          for (s = hexdata; ;)
+            {
+              es_fprintf (fp, "\t%.64s\n", s);
+              if (strlen (s) < 64)
+                break;
+              s += 64;
+            }
+          es_fputs ("\t)\n\n", fp);
+        }
+    }
+
+  /* Make sure it is a string and write it.  */
+  es_fputc (0, fp);
+  {
+    void *vp;
+
+    if (es_fclose_snatch (fp, &vp, NULL))
+      {
+        err = gpg_error_from_syserror ();
+        goto leave;
+      }
+    fp = NULL;
+    iobuf_writestr (out, vp);
+    es_free (vp);
+  }
+  err = 0;
+
+ leave:
+  xfree (hash);
+  xfree (mbox);
+  es_fclose (fp);
+  xfree (hexdata);
+  xfree (hexfpr);
+  return err;
+}
+
+
+/* Helper for do_export_stream which writes one keyblock to OUT.  */
+static gpg_error_t
+do_export_one_keyblock (ctrl_t ctrl, kbnode_t keyblock, u32 *keyid,
+                        iobuf_t out, int secret, unsigned int options,
+                        export_stats_t stats, int *any,
+                        KEYDB_SEARCH_DESC *desc, size_t ndesc,
+                        size_t descindex, gcry_cipher_hd_t cipherhd)
+{
+  gpg_error_t err = gpg_error (GPG_ERR_NOT_FOUND);
+  char *cache_nonce = NULL;
+  subkey_list_t subkey_list = NULL;  /* Track already processed subkeys. */
+  int skip_until_subkey = 0;
+  int cleartext = 0;
+  char *hexgrip = NULL;
+  char *serialno = NULL;
+  PKT_public_key *pk;
+  u32 subkidbuf[2], *subkid;
+  kbnode_t kbctx, node;
+
+  /* NB: walk_kbnode skips packets marked as deleted.  */
+  for (kbctx=NULL; (node = walk_kbnode (keyblock, &kbctx, 0)); )
+    {
+      if (skip_until_subkey)
+        {
+          if (node->pkt->pkttype == PKT_PUBLIC_SUBKEY)
+            skip_until_subkey = 0;
+          else
+            continue;
+        }
+
+      /* We used to use comment packets, but not any longer.  In
+       * case we still have comments on a key, strip them here
+       * before we call build_packet(). */
+      if (node->pkt->pkttype == PKT_COMMENT)
+        continue;
+
+      /* Skip ring trust packets - they should not ne here anyway.  */
+      if (node->pkt->pkttype == PKT_RING_TRUST)
+        continue;
+
+      /* If exact is set, then we only export what was requested
+       * (plus the primary key, if the user didn't specifically
+       * request it). */
+      if (desc[descindex].exact && node->pkt->pkttype == PKT_PUBLIC_SUBKEY)
+        {
+          if (!exact_subkey_match_p (desc+descindex, node))
+            {
+              /* Before skipping this subkey, check whether any
+               * other description wants an exact match on a
+               * subkey and include that subkey into the output
+               * too.  Need to add this subkey to a list so that
+               * it won't get processed a second time.
+               *
+               * So the first step here is to check that list and
+               * skip in any case if the key is in that list.
+               *
+               * We need this whole mess because the import
+               * function of GnuPG < 2.1 is not able to merge
+               * secret keys and thus it is useless to output them
+               * as two separate keys and have import merge them.
+               */
+              if (subkey_in_list_p (subkey_list, node))
+                skip_until_subkey = 1; /* Already processed this one. */
+              else
+                {
+                  size_t j;
+
+                  for (j=0; j < ndesc; j++)
+                    if (j != descindex && desc[j].exact
+                        && exact_subkey_match_p (desc+j, node))
+                      break;
+                  if (!(j < ndesc))
+                    skip_until_subkey = 1; /* No other one matching. */
+                }
+            }
+
+          if (skip_until_subkey)
+            continue;
+
+          /* Mark this one as processed. */
+          {
+            subkey_list_t tmp = new_subkey_list_item (node);
+            tmp->next = subkey_list;
+            subkey_list = tmp;
+          }
+        }
+
+      if (node->pkt->pkttype == PKT_SIGNATURE)
+        {
+          /* Do not export packets which are marked as not
+           * exportable.  */
+          if (!(options & EXPORT_LOCAL_SIGS)
+              && !node->pkt->pkt.signature->flags.exportable)
+            continue; /* not exportable */
+
+          /* Do not export packets with a "sensitive" revocation key
+           * unless the user wants us to.  Note that we do export
+           * these when issuing the actual revocation (see revoke.c). */
+          if (!(options & EXPORT_SENSITIVE_REVKEYS)
+              && node->pkt->pkt.signature->revkey)
+            {
+              int i;
+
+              for (i = 0; i < node->pkt->pkt.signature->numrevkeys; i++)
+                if ((node->pkt->pkt.signature->revkey[i].class & 0x40))
+                  break;
+              if (i < node->pkt->pkt.signature->numrevkeys)
+                continue;
+            }
+        }
+
+      /* Don't export attribs? */
+      if (!(options & EXPORT_ATTRIBUTES)
+          && node->pkt->pkttype == PKT_USER_ID
+          && node->pkt->pkt.user_id->attrib_data)
+        {
+          /* Skip until we get to something that is not an attrib or a
+           * signature on an attrib.  */
+          while (kbctx->next && kbctx->next->pkt->pkttype == PKT_SIGNATURE)
+            kbctx = kbctx->next;
+
+          continue;
+        }
+
+      if (secret && (node->pkt->pkttype == PKT_PUBLIC_KEY
+                     || node->pkt->pkttype == PKT_PUBLIC_SUBKEY))
+        {
+          pk = node->pkt->pkt.public_key;
+          if (node->pkt->pkttype == PKT_PUBLIC_KEY)
+            subkid = NULL;
+          else
+            {
+              keyid_from_pk (pk, subkidbuf);
+              subkid = subkidbuf;
+            }
+
+          if (pk->seckey_info)
+            {
+              log_error ("key %s: oops: seckey_info already set"
+                         " - skipped\n", keystr_with_sub (keyid, subkid));
+              skip_until_subkey = 1;
+              continue;
+            }
+
+          xfree (hexgrip);
+          err = hexkeygrip_from_pk (pk, &hexgrip);
+          if (err)
+            {
+              log_error ("key %s: error computing keygrip: %s"
+                         " - skipped\n", keystr_with_sub (keyid, subkid),
+                         gpg_strerror (err));
+              skip_until_subkey = 1;
+              err = 0;
+              continue;
+            }
+
+          xfree (serialno);
+          serialno = NULL;
+          if (secret == 2 && node->pkt->pkttype == PKT_PUBLIC_KEY)
+            {
+              /* We are asked not to export the secret parts of the
+               * primary key.  Make up an error code to create the
+               * stub.  */
+              err = GPG_ERR_NOT_FOUND;
+            }
+          else
+            err = agent_get_keyinfo (ctrl, hexgrip, &serialno, &cleartext);
+
+          if ((!err && serialno)
+              && secret == 2 && node->pkt->pkttype == PKT_PUBLIC_KEY)
+            {
+              /* It does not make sense to export a key with its
+               * primary key on card using a non-key stub.  Thus we
+               * skip those keys when used with --export-secret-subkeys. */
+              log_info (_("key %s: key material on-card - skipped\n"),
+                        keystr_with_sub (keyid, subkid));
+              skip_until_subkey = 1;
+            }
+          else if (gpg_err_code (err) == GPG_ERR_NOT_FOUND
+                   || (!err && serialno))
+            {
+              /* Create a key stub.  */
+              struct seckey_info *ski;
+              const char *s;
+
+              pk->seckey_info = ski = xtrycalloc (1, sizeof *ski);
+              if (!ski)
+                {
+                  err = gpg_error_from_syserror ();
+                  goto leave;
+                }
+
+              ski->is_protected = 1;
+              if (err)
+                ski->s2k.mode = 1001; /* GNU dummy (no secret key).  */
+              else
+                {
+                  ski->s2k.mode = 1002; /* GNU-divert-to-card.  */
+                  for (s=serialno; sizeof (ski->ivlen) && *s && s[1];
+                       ski->ivlen++, s += 2)
+                    ski->iv[ski->ivlen] = xtoi_2 (s);
+                }
+
+              if ((options & EXPORT_BACKUP))
+                err = build_packet_and_meta (out, node->pkt);
+              else
+                err = build_packet (out, node->pkt);
+              if (!err && node->pkt->pkttype == PKT_PUBLIC_KEY)
+                {
+                  stats->exported++;
+                  print_status_exported (node->pkt->pkt.public_key);
+                }
+            }
+          else if (!err)
+            {
+              err = receive_seckey_from_agent (ctrl, cipherhd,
+                                               cleartext, &cache_nonce,
+                                               hexgrip, pk);
+              if (err)
+                {
+                  if (gpg_err_code (err) == GPG_ERR_FULLY_CANCELED)
+                    goto leave;
+                  skip_until_subkey = 1;
+                  err = 0;
+                }
+              else
+                {
+                  if ((options & EXPORT_BACKUP))
+                    err = build_packet_and_meta (out, node->pkt);
+                  else
+                    err = build_packet (out, node->pkt);
+                  if (node->pkt->pkttype == PKT_PUBLIC_KEY)
+                    {
+                      stats->exported++;
+                      print_status_exported (node->pkt->pkt.public_key);
+                    }
+                }
+            }
+          else
+            {
+              log_error ("key %s: error getting keyinfo from agent: %s"
+                         " - skipped\n", keystr_with_sub (keyid, subkid),
+                             gpg_strerror (err));
+              skip_until_subkey = 1;
+              err = 0;
+            }
+
+          xfree (pk->seckey_info);
+          pk->seckey_info = NULL;
+          {
+            int i;
+            for (i = pubkey_get_npkey (pk->pubkey_algo);
+                 i < pubkey_get_nskey (pk->pubkey_algo); i++)
+              {
+                gcry_mpi_release (pk->pkey[i]);
+                pk->pkey[i] = NULL;
+              }
+          }
+        }
+      else /* Not secret or common packets.  */
+        {
+          if ((options & EXPORT_BACKUP))
+            err = build_packet_and_meta (out, node->pkt);
+          else
+            err = build_packet (out, node->pkt);
+          if (!err && node->pkt->pkttype == PKT_PUBLIC_KEY)
+            {
+              stats->exported++;
+              print_status_exported (node->pkt->pkt.public_key);
+            }
+        }
+
+      if (err)
+        {
+          log_error ("build_packet(%d) failed: %s\n",
+                     node->pkt->pkttype, gpg_strerror (err));
+          goto leave;
+        }
+
+      if (!skip_until_subkey)
+        *any = 1;
+    }
+
+ leave:
+  release_subkey_list (subkey_list);
+  xfree (serialno);
+  xfree (hexgrip);
+  xfree (cache_nonce);
+  return err;
+}
+
+
+/* Export the keys identified by the list of strings in USERS to the
+   stream OUT.  If SECRET is false public keys will be exported.  With
+   secret true secret keys will be exported; in this case 1 means the
+   entire secret keyblock and 2 only the subkeys.  OPTIONS are the
+   export options to apply.  If KEYBLOCK_OUT is not NULL, AND the exit
+   code is zero, a pointer to the first keyblock found and exported
+   will be stored at this address; no other keyblocks are exported in
+   this case.  The caller must free the returned keyblock.  If any
+   key has been exported true is stored at ANY. */
+static int
+do_export_stream (ctrl_t ctrl, iobuf_t out, strlist_t users, int secret,
+		  kbnode_t *keyblock_out, unsigned int options,
+                  export_stats_t stats, int *any)
+{
+  gpg_error_t err = 0;
+  PACKET pkt;
+  kbnode_t keyblock = NULL;
+  kbnode_t node;
+  size_t ndesc, descindex;
+  KEYDB_SEARCH_DESC *desc = NULL;
+  KEYDB_HANDLE kdbhd;
+  strlist_t sl;
+  gcry_cipher_hd_t cipherhd = NULL;
+  struct export_stats_s dummystats;
+  iobuf_t out_help = NULL;
+
+  if (!stats)
+    stats = &dummystats;
+  *any = 0;
+  init_packet (&pkt);
+  kdbhd = keydb_new ();
+  if (!kdbhd)
+    return gpg_error_from_syserror ();
+
+  /* For the PKA and DANE format open a helper iobuf and for DANE
+   * enforce some options.  */
+  if ((options & (EXPORT_PKA_FORMAT | EXPORT_DANE_FORMAT)))
+    {
+      out_help = iobuf_temp ();
+      if ((options & EXPORT_DANE_FORMAT))
+        options |= EXPORT_MINIMAL | EXPORT_CLEAN;
+    }
+
+  if (!users)
+    {
+      ndesc = 1;
+      desc = xcalloc (ndesc, sizeof *desc);
+      desc[0].mode = KEYDB_SEARCH_MODE_FIRST;
+    }
+  else
+    {
+      for (ndesc=0, sl=users; sl; sl = sl->next, ndesc++)
+        ;
+      desc = xmalloc ( ndesc * sizeof *desc);
+
+      for (ndesc=0, sl=users; sl; sl = sl->next)
+        {
+          if (!(err=classify_user_id (sl->d, desc+ndesc, 1)))
+            ndesc++;
+          else
+            log_error (_("key \"%s\" not found: %s\n"),
+                       sl->d, gpg_strerror (err));
+        }
+
+      keydb_disable_caching (kdbhd);  /* We are looping the search.  */
+
+      /* It would be nice to see which of the given users did actually
+         match one in the keyring.  To implement this we need to have
+         a found flag for each entry in desc.  To set this flag we
+         must check all those entries after a match to mark all
+         matched one - currently we stop at the first match.  To do
+         this we need an extra flag to enable this feature.  */
+    }
+
+#ifdef ENABLE_SELINUX_HACKS
+  if (secret)
+    {
+      log_error (_("exporting secret keys not allowed\n"));
+      err = gpg_error (GPG_ERR_NOT_SUPPORTED);
+      goto leave;
+    }
+#endif
+
+  /* For secret key export we need to setup a decryption context.  */
+  if (secret)
+    {
+      void *kek = NULL;
+      size_t keklen;
+
+      err = agent_keywrap_key (ctrl, 1, &kek, &keklen);
+      if (err)
+        {
+          log_error ("error getting the KEK: %s\n", gpg_strerror (err));
+          goto leave;
+        }
+
+      /* Prepare a cipher context.  */
+      err = gcry_cipher_open (&cipherhd, GCRY_CIPHER_AES128,
+                              GCRY_CIPHER_MODE_AESWRAP, 0);
+      if (!err)
+        err = gcry_cipher_setkey (cipherhd, kek, keklen);
+      if (err)
+        {
+          log_error ("error setting up an encryption context: %s\n",
+                     gpg_strerror (err));
+          goto leave;
+        }
+      xfree (kek);
+      kek = NULL;
+    }
+
+  for (;;)
+    {
+      u32 keyid[2];
+      PKT_public_key *pk;
+
+      err = keydb_search (kdbhd, desc, ndesc, &descindex);
+      if (!users)
+        desc[0].mode = KEYDB_SEARCH_MODE_NEXT;
+      if (err)
+        break;
+
+      /* Read the keyblock. */
+      release_kbnode (keyblock);
+      keyblock = NULL;
+      err = keydb_get_keyblock (kdbhd, &keyblock);
+      if (err)
+        {
+          log_error (_("error reading keyblock: %s\n"), gpg_strerror (err));
+          goto leave;
+	}
+
+      node = find_kbnode (keyblock, PKT_PUBLIC_KEY);
+      if (!node)
+        {
+          log_error ("public key packet not found in keyblock - skipped\n");
+          continue;
+        }
+      stats->count++;
+      setup_main_keyids (keyblock);  /* gpg_format_keydesc needs it.  */
+      pk = node->pkt->pkt.public_key;
+      keyid_from_pk (pk, keyid);
+
+      /* If a secret key export is required we need to check whether
+         we have a secret key at all and if so create the seckey_info
+         structure.  */
+      if (secret)
+        {
+          if (agent_probe_any_secret_key (ctrl, keyblock))
+            continue;  /* No secret key (neither primary nor subkey).  */
+
+          /* No v3 keys with GNU mode 1001. */
+          if (secret == 2 && pk->version == 3)
+            {
+              log_info (_("key %s: PGP 2.x style key - skipped\n"),
+                        keystr (keyid));
+              continue;
+            }
+
+          /* The agent does not yet allow export of v3 packets.  It is
+             actually questionable whether we should allow them at
+             all.  */
+          if (pk->version == 3)
+            {
+              log_info ("key %s: PGP 2.x style key (v3) export "
+                        "not yet supported - skipped\n", keystr (keyid));
+              continue;
+            }
+          stats->secret_count++;
+        }
+
+      /* Always do the cleaning on the public key part if requested.
+       * A designated revocation is never stripped, even with
+       * export-minimal set.  */
+      if ((options & EXPORT_CLEAN))
+        {
+          merge_keys_and_selfsig (ctrl, keyblock);
+          clean_all_uids (ctrl, keyblock, opt.verbose,
+                          (options&EXPORT_MINIMAL), NULL, NULL);
+          clean_all_subkeys (ctrl, keyblock, opt.verbose,
+                             (options&EXPORT_MINIMAL)? KEY_CLEAN_ALL
+                             /**/                    : KEY_CLEAN_AUTHENCR,
+                             NULL, NULL);
+          commit_kbnode (&keyblock);
+        }
+
+      if (export_keep_uid)
+        {
+          commit_kbnode (&keyblock);
+          apply_keep_uid_filter (ctrl, keyblock, export_keep_uid);
+          commit_kbnode (&keyblock);
+        }
+
+      if (export_drop_subkey)
+        {
+          commit_kbnode (&keyblock);
+          apply_drop_subkey_filter (ctrl, keyblock, export_drop_subkey);
+          commit_kbnode (&keyblock);
+        }
+
+      /* And write it. */
+      err = do_export_one_keyblock (ctrl, keyblock, keyid,
+                                    out_help? out_help : out,
+                                    secret, options, stats, any,
+                                    desc, ndesc, descindex, cipherhd);
+      if (err)
+        break;
+
+      if (keyblock_out)
+        {
+          *keyblock_out = keyblock;
+          break;
+        }
+
+      if (out_help)
+        {
+          /* We want to write PKA or DANE records.  OUT_HELP has the
+           * keyblock and we print a record for each uid to OUT. */
+          const void *data;
+          size_t datalen;
+
+          iobuf_flush_temp (out_help);
+          data = iobuf_get_temp_buffer (out_help);
+          datalen = iobuf_get_temp_length (out_help);
+
+          err = print_pka_or_dane_records (out,
+                                           keyblock, pk, data, datalen,
+                                           (options & EXPORT_PKA_FORMAT),
+                                           (options & EXPORT_DANE_FORMAT));
+          if (err)
+            goto leave;
+
+          iobuf_close (out_help);
+          out_help = iobuf_temp ();
+        }
+
+    }
+  if (gpg_err_code (err) == GPG_ERR_NOT_FOUND)
+    err = 0;
+
+ leave:
+  iobuf_cancel (out_help);
+  gcry_cipher_close (cipherhd);
+  xfree(desc);
+  keydb_release (kdbhd);
+  if (err || !keyblock_out)
+    release_kbnode( keyblock );
+  if( !*any )
+    log_info(_("WARNING: nothing exported\n"));
+  return err;
+}
+
+
+
+
+static gpg_error_t
+key_to_sshblob (membuf_t *mb, const char *identifier, ...)
+{
+  va_list arg_ptr;
+  gpg_error_t err = 0;
+  unsigned char nbuf[4];
+  unsigned char *buf;
+  size_t buflen;
+  gcry_mpi_t a;
+
+  ulongtobuf (nbuf, (ulong)strlen (identifier));
+  put_membuf (mb, nbuf, 4);
+  put_membuf_str (mb, identifier);
+  if (!strncmp (identifier, "ecdsa-sha2-", 11))
+    {
+      ulongtobuf (nbuf, (ulong)strlen (identifier+11));
+      put_membuf (mb, nbuf, 4);
+      put_membuf_str (mb, identifier+11);
+    }
+  va_start (arg_ptr, identifier);
+  while ((a = va_arg (arg_ptr, gcry_mpi_t)))
+    {
+      err = gcry_mpi_aprint (GCRYMPI_FMT_SSH, &buf, &buflen, a);
+      if (err)
+        break;
+      if (!strcmp (identifier, "ssh-ed25519")
+          && buflen > 5 && buf[4] == 0x40)
+        {
+          /* We need to strip our 0x40 prefix.  */
+          put_membuf (mb, "\x00\x00\x00\x20", 4);
+          put_membuf (mb, buf+5, buflen-5);
+        }
+      else
+        put_membuf (mb, buf, buflen);
+      gcry_free (buf);
+    }
+  va_end (arg_ptr);
+  return err;
+}
+
+/* Export the key identified by USERID in the SSH public key format.
+   The function exports the latest subkey with Authentication
+   capability unless the '!' suffix is used to export a specific
+   key.  */
+gpg_error_t
+export_ssh_key (ctrl_t ctrl, const char *userid)
+{
+  gpg_error_t err;
+  kbnode_t keyblock = NULL;
+  KEYDB_SEARCH_DESC desc;
+  u32 latest_date;
+  u32 curtime = make_timestamp ();
+  kbnode_t latest_key, node;
+  PKT_public_key *pk;
+  const char *identifier = NULL;
+  membuf_t mb;
+  estream_t fp = NULL;
+  struct b64state b64_state;
+  const char *fname = "-";
+
+  init_membuf (&mb, 4096);
+
+  /* We need to know whether the key has been specified using the
+     exact syntax ('!' suffix).  Thus we need to run a
+     classify_user_id on our own.  */
+  err = classify_user_id (userid, &desc, 1);
+
+  /* Get the public key.  */
+  if (!err)
+    {
+      getkey_ctx_t getkeyctx;
+
+      err = get_pubkey_byname (ctrl, GET_PUBKEY_NO_AKL,
+                               &getkeyctx, NULL, userid, &keyblock,
+                               NULL,
+                               0  /* Only usable keys or given exact. */);
+      if (!err)
+        {
+          err = getkey_next (ctrl, getkeyctx, NULL, NULL);
+          if (!err)
+            err = gpg_error (GPG_ERR_AMBIGUOUS_NAME);
+          else if (gpg_err_code (err) == GPG_ERR_NO_PUBKEY)
+            err = 0;
+        }
+      getkey_end (ctrl, getkeyctx);
+    }
+  if (err)
+    {
+      log_error (_("key \"%s\" not found: %s\n"), userid, gpg_strerror (err));
+      return err;
+    }
+
+  /* The finish_lookup code in getkey.c does not handle auth keys,
+     thus we have to duplicate the code here to find the latest
+     subkey.  However, if the key has been found using an exact match
+     ('!' notation) we use that key without any further checks and
+     even allow the use of the primary key. */
+  latest_date = 0;
+  latest_key = NULL;
+  for (node = keyblock; node; node = node->next)
+    {
+      if ((node->pkt->pkttype == PKT_PUBLIC_SUBKEY
+           || node->pkt->pkttype == PKT_PUBLIC_KEY)
+          && node->pkt->pkt.public_key->flags.exact)
+        {
+          latest_key = node;
+          break;
+        }
+    }
+  if (!latest_key)
+    {
+      for (node = keyblock; node; node = node->next)
+        {
+          if (node->pkt->pkttype != PKT_PUBLIC_SUBKEY)
+            continue;
+
+          pk = node->pkt->pkt.public_key;
+          if (DBG_LOOKUP)
+            log_debug ("\tchecking subkey %08lX\n",
+                       (ulong) keyid_from_pk (pk, NULL));
+          if (!(pk->pubkey_usage & PUBKEY_USAGE_AUTH))
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tsubkey not usable for authentication\n");
+              continue;
+            }
+          if (!pk->flags.valid)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tsubkey not valid\n");
+              continue;
+            }
+          if (pk->flags.revoked)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tsubkey has been revoked\n");
+              continue;
+            }
+          if (pk->has_expired)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tsubkey has expired\n");
+              continue;
+            }
+          if (pk->timestamp > curtime && !opt.ignore_valid_from)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tsubkey not yet valid\n");
+              continue;
+            }
+          if (DBG_LOOKUP)
+            log_debug ("\tsubkey might be fine\n");
+          /* In case a key has a timestamp of 0 set, we make sure that it
+             is used.  A better change would be to compare ">=" but that
+             might also change the selected keys and is as such a more
+             intrusive change.  */
+          if (pk->timestamp > latest_date || (!pk->timestamp && !latest_date))
+            {
+              latest_date = pk->timestamp;
+              latest_key = node;
+            }
+        }
+
+      /* If no subkey was suitable check the primary key.  */
+      if (!latest_key
+          && (node = keyblock) && node->pkt->pkttype == PKT_PUBLIC_KEY)
+        {
+          pk = node->pkt->pkt.public_key;
+          if (DBG_LOOKUP)
+            log_debug ("\tchecking primary key %08lX\n",
+                       (ulong) keyid_from_pk (pk, NULL));
+          if (!(pk->pubkey_usage & PUBKEY_USAGE_AUTH))
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tprimary key not usable for authentication\n");
+            }
+          else if (!pk->flags.valid)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tprimary key not valid\n");
+            }
+          else if (pk->flags.revoked)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tprimary key has been revoked\n");
+            }
+          else if (pk->has_expired)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tprimary key has expired\n");
+            }
+          else if (pk->timestamp > curtime && !opt.ignore_valid_from)
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tprimary key not yet valid\n");
+            }
+          else
+            {
+              if (DBG_LOOKUP)
+                log_debug ("\tprimary key is fine\n");
+              latest_date = pk->timestamp;
+              latest_key = node;
+            }
+        }
+    }
+
+  if (!latest_key)
+    {
+      err = gpg_error (GPG_ERR_UNUSABLE_PUBKEY);
+      log_error (_("key \"%s\" not found: %s\n"), userid, gpg_strerror (err));
+      goto leave;
+    }
+
+  pk = latest_key->pkt->pkt.public_key;
+  if (DBG_LOOKUP)
+    log_debug ("\tusing key %08lX\n", (ulong) keyid_from_pk (pk, NULL));
+
+  switch (pk->pubkey_algo)
+    {
+    case PUBKEY_ALGO_DSA:
+      identifier = "ssh-dss";
+      err = key_to_sshblob (&mb, identifier,
+                            pk->pkey[0], pk->pkey[1], pk->pkey[2], pk->pkey[3],
+                            NULL);
+      break;
+
+    case PUBKEY_ALGO_RSA:
+    case PUBKEY_ALGO_RSA_S:
+      identifier = "ssh-rsa";
+      err = key_to_sshblob (&mb, identifier, pk->pkey[1], pk->pkey[0], NULL);
+      break;
+
+    case PUBKEY_ALGO_ECDSA:
+      {
+        char *curveoid;
+        const char *curve;
+
+        curveoid = openpgp_oid_to_str (pk->pkey[0]);
+        if (!curveoid)
+          err = gpg_error_from_syserror ();
+        else if (!(curve = openpgp_oid_to_curve (curveoid, 0)))
+          err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
+        else
+          {
+            if (!strcmp (curve, "nistp256"))
+              identifier = "ecdsa-sha2-nistp256";
+            else if (!strcmp (curve, "nistp384"))
+              identifier = "ecdsa-sha2-nistp384";
+            else if (!strcmp (curve, "nistp521"))
+              identifier = "ecdsa-sha2-nistp521";
+
+            if (!identifier)
+              err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
+            else
+              err = key_to_sshblob (&mb, identifier, pk->pkey[1], NULL);
+          }
+        xfree (curveoid);
+      }
+      break;
+
+    case PUBKEY_ALGO_EDDSA:
+      if (!openpgp_oid_is_ed25519 (pk->pkey[0]))
+        err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
+      else
+        {
+          identifier = "ssh-ed25519";
+          err = key_to_sshblob (&mb, identifier, pk->pkey[1], NULL);
+        }
+      break;
+
+    case PUBKEY_ALGO_ELGAMAL_E:
+    case PUBKEY_ALGO_ELGAMAL:
+      err = gpg_error (GPG_ERR_UNUSABLE_PUBKEY);
+      break;
+
+    default:
+      err = GPG_ERR_PUBKEY_ALGO;
+      break;
+    }
+
+  if (!identifier)
+    goto leave;
+
+  if (opt.outfile && *opt.outfile && strcmp (opt.outfile, "-"))
+    fp = es_fopen ((fname = opt.outfile), "w");
+  else
+    fp = es_stdout;
+  if (!fp)
+    {
+      err = gpg_error_from_syserror ();
+      log_error (_("error creating '%s': %s\n"), fname, gpg_strerror (err));
+      goto leave;
+    }
+
+  es_fprintf (fp, "%s ", identifier);
+  err = b64enc_start_es (&b64_state, fp, "");
+  if (!err)
+    {
+      void *blob;
+      size_t bloblen;
+
+      blob = get_membuf (&mb, &bloblen);
+      if (blob)
+        {
+          err = b64enc_write (&b64_state, blob, bloblen);
+          xfree (blob);
+          if (err)
+            goto leave;
+        }
+      err = b64enc_finish (&b64_state);
+    }
+  if (err)
+    goto leave;
+  es_fprintf (fp, " openpgp:0x%08lX\n", (ulong)keyid_from_pk (pk, NULL));
+
+  if (es_ferror (fp))
+    err = gpg_error_from_syserror ();
+  else
+    {
+      if (fp != es_stdout && es_fclose (fp))
+        err = gpg_error_from_syserror ();
+      fp = NULL;
+    }
+
+  if (err)
+    log_error (_("error writing '%s': %s\n"), fname, gpg_strerror (err));
+
+ leave:
+  if (fp != es_stdout)
+    es_fclose (fp);
+  xfree (get_membuf (&mb, NULL));
+  release_kbnode (keyblock);
+  return err;
+}