diff --git a/sm/certchain.c b/sm/certchain.c
index 53bdea612..d4047fd53 100644
--- a/sm/certchain.c
+++ b/sm/certchain.c
@@ -440,7 +440,7 @@ check_cert_policy (ksba_cert_t cert, int listmode, estream_t fplist)
 
 /* Helper function for find_up.  This resets the key handle and search
    for an issuer ISSUER with a subjectKeyIdentifier of KEYID.  Returns
-   0 on success or -1 when not found. */
+   0 on success or GPG_ERR_NOT_FOUND when not found. */
 static int
 find_up_search_by_keyid (ctrl_t ctrl, KEYDB_HANDLE kh,
                          const char *issuer, ksba_sexp_t keyid)
@@ -460,7 +460,7 @@ find_up_search_by_keyid (ctrl_t ctrl, KEYDB_HANDLE kh,
       if (rc)
         {
           log_error ("keydb_get_cert() failed: rc=%d\n", rc);
-          rc = -1;
+          rc = gpg_error (GPG_ERR_NOT_FOUND);
           goto leave;
         }
       xfree (subj);
@@ -475,7 +475,7 @@ find_up_search_by_keyid (ctrl_t ctrl, KEYDB_HANDLE kh,
               if (rc)
                 {
                   log_error ("keydb_get_validity() failed: rc=%d\n", rc);
-                  rc = -1;
+                  rc = gpg_error (GPG_ERR_NOT_FOUND);
                   goto leave;
                 }
 
@@ -544,7 +544,7 @@ find_up_search_by_keyid (ctrl_t ctrl, KEYDB_HANDLE kh,
   if (rc)
     {
       log_error ("keydb_get_validity() failed: rc=%d\n", rc);
-      rc = -1;
+      rc = gpg_error (GPG_ERR_NOT_FOUND);
       goto leave;
     }
   if (*not_after && strcmp (ctrl->current_time, not_after) > 0 )
@@ -558,7 +558,7 @@ find_up_search_by_keyid (ctrl_t ctrl, KEYDB_HANDLE kh,
       if (rc)
         {
           log_error ("keydb_search_fpr() failed: rc=%d\n", rc);
-          rc = -1;
+          rc = gpg_error (GPG_ERR_NOT_FOUND);
           goto leave;
         }
       /* Ready.  The NE_FOUND_CERT is available via keydb_get_cert.  */
@@ -569,7 +569,7 @@ find_up_search_by_keyid (ctrl_t ctrl, KEYDB_HANDLE kh,
   ksba_cert_release (ne_found_cert);
   ksba_cert_release (cert);
   xfree (subj);
-  return rc? -1:0;
+  return rc? gpg_error (GPG_ERR_NOT_FOUND) : 0;
 }
 
 
@@ -646,10 +646,10 @@ find_up_external (ctrl_t ctrl, KEYDB_HANDLE kh,
   if (rc)
     {
       log_error ("external key lookup failed: %s\n", gpg_strerror (rc));
-      rc = -1;
+      rc = gpg_error (GPG_ERR_NOT_FOUND);
     }
   else if (!find_up_store_certs_parm.count)
-    rc = -1;
+    rc = gpg_err_code (rc) == GPG_ERR_NOT_FOUND;
   else
     {
       int old;
@@ -818,7 +818,8 @@ find_up_dirmngr (ctrl_t ctrl, KEYDB_HANDLE kh,
   if (rc && !opt.quiet)
     log_info (_("dirmngr cache-only key lookup failed: %s\n"),
               gpg_strerror (rc));
-  return (!rc && find_up_store_certs_parm.count)? 0 : -1;
+  return ((!rc && find_up_store_certs_parm.count)
+          ? 0 : gpg_error (GPG_ERR_NOT_FOUND));
 }
 
 
@@ -828,7 +829,7 @@ find_up_dirmngr (ctrl_t ctrl, KEYDB_HANDLE kh,
    FIND_NEXT is true, the function shall return the next possible
    issuer.  The certificate itself is not directly returned but a
    keydb_get_cert on the keydb context KH will return it.  Returns 0
-   on success, -1 if not found or an error code.  */
+   on success, GPG_ERR_NOT_FOUND if not found or another error code.  */
 static int
 find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
          ksba_cert_t cert, const char *issuer, int find_next)
@@ -857,13 +858,13 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
              into the ephemeral DB and let the code below do the
              actual retrieve.  Thus there is no error checking.
              Skipped in find_next mode as usual. */
-          if (rc == -1 && !find_next)
+          if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && !find_next)
             find_up_dirmngr (ctrl, kh, authidno, s, 0);
 
           /* In case of an error try the ephemeral DB.  We can't do
              that in find_next mode because we can't keep the search
              state then. */
-          if (rc == -1 && !find_next)
+          if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && !find_next)
             {
               int old = keydb_set_ephemeral (kh, 1);
               if (!old)
@@ -877,11 +878,11 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
                 }
               keydb_set_ephemeral (kh, old);
             }
-          if (rc)
-            rc = -1; /* Need to make sure to have this error code. */
+          if (rc) /* Need to make sure to have this error code. */
+            rc = gpg_error (GPG_ERR_NOT_FOUND);
         }
 
-      if (rc == -1 && keyid && !find_next)
+      if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && keyid && !find_next)
         {
           /* Not found by AKI.issuer_sn.  Lets try the AKI.ki
              instead. Loop over all certificates with that issuer as
@@ -900,13 +901,13 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
                 log_debug ("  found via authid and keyid (ephem)\n");
               keydb_set_ephemeral (kh, old);
             }
-          if (rc)
-            rc = -1; /* Need to make sure to have this error code. */
+          if (rc) /* Need to make sure to have this error code. */
+            rc = gpg_error (GPG_ERR_NOT_FOUND);
         }
 
       /* If we still didn't found it, try to find it via the subject
          from the dirmngr-cache.  */
-      if (rc == -1 && !find_next)
+      if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && !find_next)
         {
           if (!find_up_dirmngr (ctrl, kh, NULL, issuer, 1))
             {
@@ -920,15 +921,16 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
                 }
               keydb_set_ephemeral (kh, old);
             }
-          if (rc)
-            rc = -1; /* Need to make sure to have this error code. */
+          if (rc) /* Need to make sure to have this error code. */
+            rc = gpg_error (GPG_ERR_NOT_FOUND);
 
           if (!rc && DBG_X509)
             log_debug ("  found via authid and issuer from dirmngr cache\n");
         }
 
       /* If we still didn't found it, try an external lookup.  */
-      if (rc == -1 && !find_next && !ctrl->offline)
+      if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND
+          && !find_next && !ctrl->offline)
         {
           /* We allow AIA also if CRLs are enabled; both can be used
            * as a web bug so it does not make sense to not use AIA if
@@ -952,9 +954,9 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
       /* Print a note so that the user does not feel too helpless when
          an issuer certificate was found and gpgsm prints BAD
          signature because it is not the correct one. */
-      if (rc == -1 && opt.quiet)
+      if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && opt.quiet)
         ;
-      else if (rc == -1)
+      else if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
         {
           log_info ("%sissuer certificate ", find_next?"next ":"");
           if (keyid)
@@ -982,7 +984,7 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
 
   if (rc) /* Not found via authorithyKeyIdentifier, try regular issuer name. */
     rc = keydb_search_subject (ctrl, kh, issuer);
-  if (rc == -1 && !find_next)
+  if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && !find_next)
     {
       int old;
 
@@ -1004,7 +1006,7 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
     }
 
   /* Still not found.  If enabled, try an external lookup.  */
-  if (rc == -1 && !find_next && !ctrl->offline)
+  if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND && !find_next && !ctrl->offline)
     {
       if ((opt.auto_issuer_key_retrieve || !opt.no_crl_check)
           && !find_up_via_auth_info_access (ctrl, kh, cert))
@@ -1026,8 +1028,8 @@ find_up (ctrl_t ctrl, KEYDB_HANDLE kh,
 
 
 /* Return the next certificate up in the chain starting at START.
-   Returns -1 when there are no more certificates. */
-int
+   Returns GPG_ERR_NOT_FOUND when there are no more certificates. */
+gpg_error_t
 gpgsm_walk_cert_chain (ctrl_t ctrl, ksba_cert_t start, ksba_cert_t *r_next)
 {
   int rc = 0;
@@ -1060,7 +1062,7 @@ gpgsm_walk_cert_chain (ctrl_t ctrl, ksba_cert_t start, ksba_cert_t *r_next)
 
   if (is_root_cert (start, issuer, subject))
     {
-      rc = -1; /* we are at the root */
+      rc = gpg_error (GPG_ERR_NOT_FOUND); /* we are at the root */
       goto leave;
     }
 
@@ -1069,7 +1071,7 @@ gpgsm_walk_cert_chain (ctrl_t ctrl, ksba_cert_t start, ksba_cert_t *r_next)
     {
       /* It is quite common not to have a certificate, so better don't
          print an error here.  */
-      if (rc != -1 && opt.verbose > 1)
+      if (gpg_err_code (rc) != GPG_ERR_NOT_FOUND && opt.verbose > 1)
         log_error ("failed to find issuer's certificate: rc=%d\n", rc);
       rc = gpg_error (GPG_ERR_MISSING_ISSUER_CERT);
       goto leave;
@@ -2340,7 +2342,7 @@ get_regtp_ca_info (ctrl_t ctrl, ksba_cert_t cert, int *chainlen)
       cert = next;
     }
   ksba_cert_release (cert);
-  if (rc != -1 || !depth || depth == DIM(array) )
+  if (gpg_err_code (rc) != GPG_ERR_NOT_FOUND || !depth || depth == DIM(array) )
     {
       /* We did not reached the root. */
       goto leave;
diff --git a/sm/certlist.c b/sm/certlist.c
index d18fce62c..61125acba 100644
--- a/sm/certlist.c
+++ b/sm/certlist.c
@@ -376,7 +376,7 @@ gpgsm_add_to_certlist (ctrl_t ctrl, const char *name, int secret,
 
             next_ambigious:
               rc = keydb_search (ctrl, kh, &desc, 1);
-              if (rc == -1)
+              if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
                 rc = 0;
               else if (!rc)
                 {
@@ -450,7 +450,7 @@ gpgsm_add_to_certlist (ctrl_t ctrl, const char *name, int secret,
                 {
                   certlist_t cl = xtrycalloc (1, sizeof *cl);
                   if (!cl)
-                    rc = out_of_core ();
+                    rc = gpg_error_from_syserror ();
                   else
                     {
                       cl->cert = cert; cert = NULL;
@@ -465,7 +465,8 @@ gpgsm_add_to_certlist (ctrl_t ctrl, const char *name, int secret,
 
   keydb_release (kh);
   ksba_cert_release (cert);
-  return rc == -1? gpg_error (GPG_ERR_NO_PUBKEY): rc;
+  return (gpg_err_code (rc) == GPG_ERR_NOT_FOUND
+          ? gpg_error (GPG_ERR_NO_PUBKEY): rc);
 }
 
 
@@ -549,7 +550,7 @@ gpgsm_find_cert (ctrl_t ctrl,
                 }
             next_ambiguous:
               rc = keydb_search (ctrl, kh, &desc, 1);
-              if (rc == -1)
+              if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
                 rc = 0;
               else
                 {
@@ -603,5 +604,6 @@ gpgsm_find_cert (ctrl_t ctrl,
     }
 
   keydb_release (kh);
-  return rc == -1? gpg_error (GPG_ERR_NO_PUBKEY): rc;
+  return (gpg_err_code (rc) == GPG_ERR_NOT_FOUND?
+          gpg_error (GPG_ERR_NO_PUBKEY): rc);
 }
diff --git a/sm/delete.c b/sm/delete.c
index 00840a4de..511ffb9b2 100644
--- a/sm/delete.c
+++ b/sm/delete.c
@@ -80,7 +80,7 @@ delete_one (ctrl_t ctrl, const char *username)
 
     next_ambigious:
       rc = keydb_search (ctrl, kh, &desc, 1);
-      if (rc == -1)
+      if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
         rc = 0;
       else if (!rc)
         {
@@ -104,7 +104,7 @@ delete_one (ctrl_t ctrl, const char *username)
     }
   if (rc)
     {
-      if (rc == -1)
+      if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
         rc = gpg_error (GPG_ERR_NO_PUBKEY);
       log_error (_("certificate '%s' not found: %s\n"),
                  username, gpg_strerror (rc));
diff --git a/sm/export.c b/sm/export.c
index bba24f0b1..32f04565f 100644
--- a/sm/export.c
+++ b/sm/export.c
@@ -295,7 +295,7 @@ gpgsm_export (ctrl_t ctrl, strlist_t names, estream_t stream)
       ksba_cert_release (cert);
       cert = NULL;
     }
-  if (rc && rc != -1)
+  if (rc && gpg_err_code (rc) != GPG_ERR_NOT_FOUND)
     log_error ("keydb_search failed: %s\n", gpg_strerror (rc));
   else if (b64writer)
     {
@@ -389,7 +389,7 @@ gpgsm_p12_export (ctrl_t ctrl, const char *name, estream_t stream, int rawmode)
             }
           err = gpg_error (GPG_ERR_AMBIGUOUS_NAME);
         }
-      else if (err == -1 || gpg_err_code (err) == GPG_ERR_EOF)
+      else if (gpg_err_code (err) == GPG_ERR_NOT_FOUND)
         err = 0;
       if (err)
         {
diff --git a/sm/gpgsm.h b/sm/gpgsm.h
index 05f06d17b..e96f15743 100644
--- a/sm/gpgsm.h
+++ b/sm/gpgsm.h
@@ -36,8 +36,14 @@
 #include "../common/ksba-io-support.h"
 #include "../common/compliance.h"
 
+/* The maximum length of a binary fingerprints.  This is used to
+ * provide a static buffer and will be increased if we need to support
+ * longer fingerprints.  */
+#define MAX_FINGERPRINT_LEN 32
+
+/* The maximum length of a binary digest.  */
+#define MAX_DIGEST_LEN 64     /* Fits for SHA-512 */
 
-#define MAX_DIGEST_LEN 64
 
 struct keyserver_spec
 {
@@ -353,8 +359,8 @@ int gpgsm_create_cms_signature (ctrl_t ctrl,
 #define VALIDATE_FLAG_CHAIN_MODEL 2
 #define VALIDATE_FLAG_STEED       4
 
-int gpgsm_walk_cert_chain (ctrl_t ctrl,
-                           ksba_cert_t start, ksba_cert_t *r_next);
+gpg_error_t gpgsm_walk_cert_chain (ctrl_t ctrl,
+                                   ksba_cert_t start, ksba_cert_t *r_next);
 int gpgsm_is_root_cert (ksba_cert_t cert);
 int gpgsm_validate_chain (ctrl_t ctrl, ksba_cert_t cert,
                           ksba_isotime_t checktime,
diff --git a/sm/import.c b/sm/import.c
index 988d127d1..8e5634182 100644
--- a/sm/import.c
+++ b/sm/import.c
@@ -550,7 +550,7 @@ gpgsm_import_files (ctrl_t ctrl, int nfiles, char **files,
           int fd = of (*files);
           rc = import_one (ctrl, &stats, fd);
           close (fd);
-          if (rc == -1)
+          if (rc == -1/* legacy*/ || gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
             rc = 0;
         }
     }
diff --git a/sm/keydb.c b/sm/keydb.c
index d7525bd76..47f8a0bce 100644
--- a/sm/keydb.c
+++ b/sm/keydb.c
@@ -68,7 +68,10 @@ struct keydb_local_s
 
   /* I/O buffer with the last search result or NULL.  Used if
    * D-lines are used to convey the keyblocks. */
-  iobuf_t search_result;
+  struct {
+    char *buf;
+    size_t len;
+  } search_result;
 
   /* This flag set while an operation is running on this context.  */
   unsigned int is_active : 1;
@@ -931,15 +934,11 @@ keydb_pop_found_state (KEYDB_HANDLE hd)
 
 
 
-/*
-  Return the last found object.  Caller must free it.  The returned
-  keyblock has the kbode flag bit 0 set for the node with the public
-  key used to locate the keyblock or flag bit 1 set for the user ID
-  node.  */
+/* Return the last found certificate.  Caller must free it.  */
 int
 keydb_get_cert (KEYDB_HANDLE hd, ksba_cert_t *r_cert)
 {
-  int rc = 0;
+  int err = 0;
 
   if (!hd)
     return gpg_error (GPG_ERR_INV_VALUE);
@@ -949,31 +948,62 @@ keydb_get_cert (KEYDB_HANDLE hd, ksba_cert_t *r_cert)
 
   if (hd->use_keyboxd)
     {
-      /* FIXME */
+      ksba_cert_t cert;
+
+      /* Fixme: We should clear that also in non-keyboxd mode but we
+       * did not in the past and thus all code should be checked
+       * whether this is okay.  If we run into error in keyboxd mode,
+       * this is a not as severe because keyboxd is currently
+       * experimental.  */
+      *r_cert = NULL;
+
+      if (!hd->kbl->search_result.buf || !hd->kbl->search_result.len)
+        {
+          err = gpg_error (GPG_ERR_VALUE_NOT_FOUND);
+          goto leave;
+        }
+      err = ksba_cert_new (&cert);
+      if (err)
+        goto leave;
+      err = ksba_cert_init_from_mem (cert,
+                                     hd->kbl->search_result.buf,
+                                     hd->kbl->search_result.len);
+      if (err)
+        {
+          ksba_cert_release (cert);
+          goto leave;
+        }
+      xfree (hd->kbl->search_result.buf);
+      hd->kbl->search_result.buf = NULL;
+      hd->kbl->search_result.len = 0;
+      *r_cert = cert;
       goto leave;
     }
 
   if ( hd->found < 0 || hd->found >= hd->used)
     {
-      rc = -1; /* nothing found */
+      /* Fixme: It would be better to use GPG_ERR_VALUE_NOT_FOUND here
+       * but for now we use NOT_FOUND because that is our standard
+       * replacement for the formerly used (-1).  */
+      err = gpg_error (GPG_ERR_NOT_FOUND); /* nothing found */
       goto leave;
     }
 
-  rc = GPG_ERR_BUG;
+  err = GPG_ERR_BUG;
   switch (hd->active[hd->found].type)
     {
     case KEYDB_RESOURCE_TYPE_NONE:
-      rc = gpg_error (GPG_ERR_GENERAL); /* oops */
+      err = gpg_error (GPG_ERR_GENERAL); /* oops */
       break;
     case KEYDB_RESOURCE_TYPE_KEYBOX:
-      rc = keybox_get_cert (hd->active[hd->found].u.kr, r_cert);
+      err = keybox_get_cert (hd->active[hd->found].u.kr, r_cert);
       break;
     }
 
  leave:
   if (DBG_CLOCK)
-    log_clock ("%s: leave (rc=%d)\n", __func__, rc);
-  return rc;
+    log_clock ("%s: leave (rc=%d)\n", __func__, err);
+  return err;
 }
 
 
@@ -995,6 +1025,8 @@ keydb_get_flags (KEYDB_HANDLE hd, int which, int idx, unsigned int *value)
   if (hd->use_keyboxd)
     {
       /* FIXME */
+      *value = 0;
+      err = 0;
       goto leave;
     }
 
@@ -1073,6 +1105,36 @@ keydb_set_flags (KEYDB_HANDLE hd, int which, int idx, unsigned int value)
   return err;
 }
 
+
+
+/* Communication object for Keyboxd STORE commands.  */
+struct store_parm_s
+{
+  assuan_context_t ctx;
+  const void *data;   /* The certificate in X.509 binary format.  */
+  size_t datalen;     /* The length of DATA.  */
+};
+
+
+/* Handle the inquiries from the STORE command.  */
+static gpg_error_t
+store_inq_cb (void *opaque, const char *line)
+{
+  struct store_parm_s *parm = opaque;
+  gpg_error_t err = 0;
+
+  if (has_leading_keyword (line, "BLOB"))
+    {
+      if (parm->data)
+        err = assuan_send_data (parm->ctx, parm->data, parm->datalen);
+    }
+  else
+    return gpg_error (GPG_ERR_ASS_UNKNOWN_INQUIRE);
+
+  return err;
+}
+
+
 /*
  * Insert a new Certificate into one of the resources.
  */
@@ -1094,7 +1156,20 @@ keydb_insert_cert (KEYDB_HANDLE hd, ksba_cert_t cert)
 
   if (hd->use_keyboxd)
     {
-      /* FIXME */
+      struct store_parm_s parm;
+
+      parm.ctx = hd->kbl->ctx;
+      parm.data = ksba_cert_get_image (cert, &parm.datalen);
+      if (!parm.data)
+        {
+          log_debug ("broken ksba cert object\n");
+          err = gpg_error (GPG_ERR_GENERAL);
+          goto leave;
+        }
+      err = assuan_transact (hd->kbl->ctx, "STORE --insert",
+                             NULL, NULL,
+                             store_inq_cb, &parm,
+                             NULL, NULL);
       goto leave;
     }
 
@@ -1246,7 +1321,7 @@ keydb_delete (KEYDB_HANDLE hd)
  * operation (which is only relevant for inserts) will be done on this
  * resource.
  */
-int
+static gpg_error_t
 keydb_locate_writable (KEYDB_HANDLE hd, const char *reserved)
 {
   int rc;
@@ -1277,7 +1352,7 @@ keydb_locate_writable (KEYDB_HANDLE hd, const char *reserved)
         }
     }
 
-  return -1;
+  return gpg_error (GPG_ERR_NOT_FOUND);
 }
 
 /*
@@ -1328,11 +1403,16 @@ keydb_search_reset (KEYDB_HANDLE hd)
   hd->found = -1;
   if (hd->use_keyboxd)
     {
-      /* FIXME */
-    }
+      /* All we need is to tell search that a reset is pending.  Note that
+       * keydb_new sets this flag as well.  To comply with the
+       * specification of keydb_delete_keyblock we also need to clear the
+       * ubid flag so that after a reset a delete can't be performed.  */
+      hd->kbl->need_search_reset = 1;
+      hd->last_ubid_valid = 0;
+   }
   else
     {
-      /* and reset all resources */
+      /* Reset all resources */
       for (i=0; !err && i < hd->used; i++)
         {
           switch (hd->active[i].type)
@@ -1404,15 +1484,59 @@ keydb_search_desc_dump (struct keydb_search_desc *desc)
 }
 
 
-/*
- * Search through all keydb resources, starting at the current position,
- * for a keyblock which contains one of the keys described in the DESC array.
- */
-int
+
+/* Status callback for SEARCH and NEXT operaions.  */
+static gpg_error_t
+search_status_cb (void *opaque, const char *line)
+{
+  KEYDB_HANDLE hd = opaque;
+  gpg_error_t err = 0;
+  const char *s;
+
+  if ((s = has_leading_keyword (line, "PUBKEY_INFO")))
+    {
+      if (atoi (s) != PUBKEY_TYPE_X509)
+        err = gpg_error (GPG_ERR_WRONG_BLOB_TYPE);
+      else
+        {
+          hd->last_ubid_valid = 0;
+          while (*s && !spacep (s))
+            s++;
+          if (hex2fixedbuf (s, hd->last_ubid, sizeof hd->last_ubid))
+            hd->last_ubid_valid = 1;
+          else
+            err = gpg_error (GPG_ERR_INV_VALUE);
+        }
+    }
+
+  return err;
+}
+
+/* Search through all keydb resources, starting at the current
+ * position, for a keyblock which contains one of the keys described
+ * in the DESC array.  In keyboxd mode the search is instead delegated
+ * to the keyboxd.
+ *
+ * DESC is an array of search terms with NDESC entries.  The search
+ * terms are or'd together.  That is, the next entry in the DB that
+ * matches any of the descriptions will be returned.
+ *
+ * Note: this function resumes searching where the last search left
+ * off (i.e., at the current file position).  If you want to search
+ * from the start of the database, then you need to first call
+ * keydb_search_reset().
+ *
+ * If no key matches the search description, the error code
+ * GPG_ERR_NOT_FOUND is retruned.  If there was a match, 0 is
+ * returned.  If an error occurred, that error code is returned.
+ *
+ * The returned key is considered to be selected and the certificate
+ * can be detched via keydb_get_cert.  */
+gpg_error_t
 keydb_search (ctrl_t ctrl, KEYDB_HANDLE hd,
               KEYDB_SEARCH_DESC *desc, size_t ndesc)
 {
-  int rc = -1;
+  gpg_error_t err = gpg_error (GPG_ERR_EOF);
   unsigned long skipped;
   int i;
 
@@ -1442,11 +1566,164 @@ keydb_search (ctrl_t ctrl, KEYDB_HANDLE hd,
 
   if (hd->use_keyboxd)
     {
-      /* FIXME */
+      char line[ASSUAN_LINELENGTH];
+
+      /* Clear the result objects.  */
+      if (hd->kbl->search_result.buf)
+        {
+          xfree (hd->kbl->search_result.buf);
+          hd->kbl->search_result.buf = NULL;
+          hd->kbl->search_result.len = 0;
+        }
+
+      /* Check whether this is a NEXT search.  */
+      if (!hd->kbl->need_search_reset)
+        {
+          /* A reset was not requested thus continue the search.  The
+           * keyboxd keeps the context of the search and thus the NEXT
+           * operates on the last search pattern.  This is the way how
+           * we always used the keydb functions.  In theory we were
+           * able to modify the search pattern between searches but
+           * that is not anymore supported by keyboxd and a cursory
+           * check does not show that we actually made use of that
+           * misfeature.  */
+          snprintf (line, sizeof line, "NEXT --x509");
+          goto do_search;
+        }
+
+      hd->kbl->need_search_reset = 0;
+
+      if (!ndesc)
+        {
+          err = gpg_error (GPG_ERR_INV_ARG);
+          goto leave;
+        }
+
+      /* FIXME: Implement --multi */
+      switch (desc->mode)
+        {
+        case KEYDB_SEARCH_MODE_EXACT:
+          snprintf (line, sizeof line, "SEARCH --x509 =%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_SUBSTR:
+          snprintf (line, sizeof line, "SEARCH --x509 *%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_MAIL:
+          snprintf (line, sizeof line, "SEARCH --x509 <%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_MAILSUB:
+          snprintf (line, sizeof line, "SEARCH --x509 @%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_MAILEND:
+          snprintf (line, sizeof line, "SEARCH --x509 .%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_WORDS:
+          snprintf (line, sizeof line, "SEARCH --x509 +%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_SHORT_KID:
+          snprintf (line, sizeof line, "SEARCH --x509 0x%08lX",
+                    (ulong)desc->u.kid[1]);
+          break;
+
+        case KEYDB_SEARCH_MODE_LONG_KID:
+          snprintf (line, sizeof line, "SEARCH --x509 0x%08lX%08lX",
+                    (ulong)desc->u.kid[0], (ulong)desc->u.kid[1]);
+          break;
+
+        case KEYDB_SEARCH_MODE_FPR:
+          {
+            unsigned char hexfpr[MAX_FINGERPRINT_LEN * 2 + 1];
+            log_assert (desc[0].fprlen <= MAX_FINGERPRINT_LEN);
+            bin2hex (desc[0].u.fpr, desc[0].fprlen, hexfpr);
+            snprintf (line, sizeof line, "SEARCH --x509 0x%s", hexfpr);
+          }
+          break;
+
+        case KEYDB_SEARCH_MODE_ISSUER:
+          snprintf (line, sizeof line, "SEARCH --x509 #/%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_ISSUER_SN:
+          if (desc[0].snhex)
+            snprintf (line, sizeof line, "SEARCH --x509 #%.*s/%s",
+                      (int)desc[0].snlen, desc[0].sn, desc[0].u.name);
+          else
+            {
+              char *hexsn = bin2hex (desc[0].sn, desc[0].snlen, NULL);
+              if (!hexsn)
+                {
+                  err = gpg_error_from_syserror ();
+                  goto leave;
+                }
+              snprintf (line, sizeof line, "SEARCH --x509 #%s/%s",
+                        hexsn, desc[0].u.name);
+              xfree (hexsn);
+            }
+          break;
+
+        case KEYDB_SEARCH_MODE_SN:
+          snprintf (line, sizeof line, "SEARCH --x509 #%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_SUBJECT:
+          snprintf (line, sizeof line, "SEARCH --x509 /%s", desc[0].u.name);
+          break;
+
+        case KEYDB_SEARCH_MODE_KEYGRIP:
+          {
+            unsigned char hexgrip[KEYGRIP_LEN * 2 + 1];
+            bin2hex (desc[0].u.grip, KEYGRIP_LEN, hexgrip);
+            snprintf (line, sizeof line, "SEARCH --x509 &%s", hexgrip);
+          }
+          break;
+
+        case KEYDB_SEARCH_MODE_UBID:
+          {
+            unsigned char hexubid[UBID_LEN * 2 + 1];
+            bin2hex (desc[0].u.ubid, UBID_LEN, hexubid);
+            snprintf (line, sizeof line, "SEARCH --x509 ^%s", hexubid);
+          }
+          break;
+
+        case KEYDB_SEARCH_MODE_FIRST:
+          snprintf (line, sizeof line, "SEARCH --x509");
+          break;
+
+        case KEYDB_SEARCH_MODE_NEXT:
+          log_debug ("%s: mode next - we should not get to here!\n", __func__);
+          snprintf (line, sizeof line, "NEXT --x509");
+          break;
+
+        default:
+          err = gpg_error (GPG_ERR_INV_ARG);
+          goto leave;
+        }
+
+    do_search:
+      hd->last_ubid_valid = 0;
+      /* To avoid silent truncation we error out on a too long line.  */
+      if (strlen (line) + 5 >= sizeof line)
+        err = gpg_error (GPG_ERR_ASS_LINE_TOO_LONG);
+      else
+        err = kbx_client_data_cmd (hd->kbl->kcd, line, search_status_cb, hd);
+      if (!err && !(err = kbx_client_data_wait (hd->kbl->kcd,
+                                                &hd->kbl->search_result.buf,
+                                                &hd->kbl->search_result.len)))
+        {
+          /* if (hd->last_ubid_valid) */
+          /*   log_printhex (hd->last_ubid, 20, "found UBID:"); */
+        }
+
     }
-  else
+  else /* Local keyring search.  */
     {
-      while ((rc == -1 || gpg_err_code (rc) == GPG_ERR_EOF)
+      while (gpg_err_code (err) == GPG_ERR_EOF
              && hd->current >= 0 && hd->current < hd->used)
         {
           switch (hd->active[hd->current].type)
@@ -1455,9 +1732,11 @@ keydb_search (ctrl_t ctrl, KEYDB_HANDLE hd,
               BUG(); /* we should never see it here */
               break;
             case KEYDB_RESOURCE_TYPE_KEYBOX:
-              rc = keybox_search (hd->active[hd->current].u.kr, desc, ndesc,
-                                  KEYBOX_BLOBTYPE_X509,
-                                  NULL, &skipped);
+              err = keybox_search (hd->active[hd->current].u.kr, desc, ndesc,
+                                   KEYBOX_BLOBTYPE_X509,
+                                   NULL, &skipped);
+              if (err == -1) /* Map legacy code.  */
+                err = gpg_error (GPG_ERR_EOF);
               break;
             }
 
@@ -1466,21 +1745,25 @@ keydb_search (ctrl_t ctrl, KEYDB_HANDLE hd,
                        __func__,
                        hd->active[hd->current].type==KEYDB_RESOURCE_TYPE_KEYBOX
                        ? "keybox" : "unknown type",
-                       hd->current, hd->used,
-                       rc == -1 ? "EOF" : gpg_strerror (rc));
+                       hd->current, hd->used, gpg_strerror (err));
 
-          if (rc == -1 || gpg_err_code (rc) == GPG_ERR_EOF)
+          if (gpg_err_code (err) == GPG_ERR_EOF)
             { /* EOF -> switch to next resource */
               hd->current++;
             }
-          else if (!rc)
+          else if (!err)
             hd->found = hd->current;
         }
     }
 
+ leave:
+  /* The NOTHING_FOUND error is triggered by a NEXT command.  */
+  if (gpg_err_code (err) == GPG_ERR_EOF
+      || gpg_err_code (err) == GPG_ERR_NOTHING_FOUND)
+    err = gpg_error (GPG_ERR_NOT_FOUND);
   if (DBG_CLOCK)
-    log_clock ("%s: leave (rc=%d)\n", __func__, rc);
-  return rc;
+    log_clock ("%s: leave (%s)\n", __func__, gpg_strerror (err));
+  return err;
 }
 
 
@@ -1621,7 +1904,7 @@ keydb_store_cert (ctrl_t ctrl, ksba_cert_t cert, int ephemeral, int *existed)
     }
 
   rc = keydb_search_fpr (ctrl, kh, fpr);
-  if (rc != -1)
+  if (gpg_err_code (rc) != GPG_ERR_NOT_FOUND)
     {
       keydb_release (kh);
       if (!rc)
@@ -1715,9 +1998,7 @@ keydb_set_cert_flags (ctrl_t ctrl, ksba_cert_t cert, int ephemeral,
   err = keydb_search_fpr (ctrl, kh, fpr);
   if (err)
     {
-      if (err == -1)
-        err = gpg_error (GPG_ERR_NOT_FOUND);
-      else
+      if (gpg_err_code (err) != gpg_error (GPG_ERR_NOT_FOUND))
         log_error (_("problem re-searching certificate: %s\n"),
                    gpg_strerror (err));
       keydb_release (kh);
@@ -1836,7 +2117,7 @@ keydb_clear_some_cert_flags (ctrl_t ctrl, strlist_t names)
             }
         }
     }
-  if (rc && rc != -1)
+  if (rc && gpg_err_code (rc) != GPG_ERR_NOT_FOUND)
     log_error ("keydb_search failed: %s\n", gpg_strerror (rc));
 
  leave:
diff --git a/sm/keydb.h b/sm/keydb.h
index 0f6e3818f..2725cadc6 100644
--- a/sm/keydb.h
+++ b/sm/keydb.h
@@ -52,11 +52,10 @@ gpg_error_t keydb_update_cert (KEYDB_HANDLE hd, ksba_cert_t cert);
 
 gpg_error_t keydb_delete (KEYDB_HANDLE hd);
 
-int keydb_locate_writable (KEYDB_HANDLE hd, const char *reserved);
 void keydb_rebuild_caches (void);
 
 gpg_error_t keydb_search_reset (KEYDB_HANDLE hd);
-int keydb_search (ctrl_t ctrl, KEYDB_HANDLE hd,
+gpg_error_t keydb_search (ctrl_t ctrl, KEYDB_HANDLE hd,
                   KEYDB_SEARCH_DESC *desc, size_t ndesc);
 int keydb_search_first (ctrl_t ctrl, KEYDB_HANDLE hd);
 int keydb_search_next (ctrl_t ctrl, KEYDB_HANDLE hd);
diff --git a/sm/keylist.c b/sm/keylist.c
index 3b0c74f55..6558d68d2 100644
--- a/sm/keylist.c
+++ b/sm/keylist.c
@@ -452,8 +452,9 @@ list_cert_colon (ctrl_t ctrl, ksba_cert_t cert, unsigned int validity,
         chain_id = chain_id_buffer;
         ksba_cert_release (next);
       }
-    else if (rc == -1)  /* We have reached the root certificate. */
+    else if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
       {
+        /* We have reached the root certificate. */
         chain_id = fpr;
         is_root = 1;
       }
@@ -1603,7 +1604,7 @@ list_internal_keys (ctrl_t ctrl, strlist_t names, estream_t fp,
       lastcert = cert;
       cert = NULL;
     }
-  if (gpg_err_code (rc) == GPG_ERR_EOF || rc == -1 )
+  if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
     rc = 0;
   if (rc)
     log_error ("keydb_search failed: %s\n", gpg_strerror (rc));
diff --git a/sm/sign.c b/sm/sign.c
index 08e30ebd6..46c71f040 100644
--- a/sm/sign.c
+++ b/sm/sign.c
@@ -291,7 +291,7 @@ add_certificate_list (ctrl_t ctrl, ksba_cms_t cms, ksba_cert_t cert)
     }
   ksba_cert_release (cert);
 
-  return rc == -1? 0: rc;
+  return gpg_err_code (rc) == GPG_ERR_NOT_FOUND? 0 : rc;
 
  ksba_failure:
   ksba_cert_release (cert);