agent: Make --disable-extended-key-format a dummy option.

* agent/agent.h (opt): Remove enable_extended_key_format.
* agent/gpg-agent.c (enum cmd_and_opt_values): Turn
oDisableExtendedKeyFormat and oEnableExtendedKeyFormat into dummy
options.

* agent/protect.c (do_encryption): Remove arg use_ocb and
corresponding code.
(agent_protect): Ditto.  Change all callers.

* agent/findkey.c (agent_write_private_key): Simplify due to the
removal of disable-extended-key-format.
(write_extended_private_key): Fold into agent_write_private_key.
--

This change is related to
GnuPG-bug-id: 6386
but should have no visible effect except for the removal of
option --disable-extended-key-format.

11 files changed, 157 insertions, 285 deletions

diff --git a/agent/agent.h b/agent/agent.h
index 303f92e50..4e7452eee 100644
--- a/agent/agent.h
+++ b/agent/agent.h
@@ -141,13 +141,6 @@ struct
      passphrase change.  */
   int enable_passphrase_history;
 
-  /* If set the extended key format is used for new keys.  Note that
-   * this may have the value 2 in which case
-   * --disable-extended-key-format won't have any effect and thus
-   * effectivley locking it.  This is required to support existing
-   * profiles which lock the use of --enable-extended-key-format. */
-  int enable_extended_key_format;
-
   int running_detached; /* We are running detached from the tty. */
 
   /* If this global option is true, the passphrase cache is ignored
@@ -566,7 +559,7 @@ unsigned char get_standard_s2k_count_rfc4880 (void);
 unsigned long get_standard_s2k_time (void);
 int agent_protect (const unsigned char *plainkey, const char *passphrase,
                    unsigned char **result, size_t *resultlen,
-		   unsigned long s2k_count, int use_ocb);
+		   unsigned long s2k_count);
 gpg_error_t agent_unprotect (ctrl_t ctrl,
                      const unsigned char *protectedkey, const char *passphrase,
                      gnupg_isotime_t protected_at,
diff --git a/agent/command-ssh.c b/agent/command-ssh.c
index 7621e7c2f..b41177be6 100644
--- a/agent/command-ssh.c
+++ b/agent/command-ssh.c
@@ -3142,7 +3142,7 @@ ssh_key_to_protected_buffer (gcry_sexp_t key, const char *passphrase,
                                    buffer_new, buffer_new_n);
 
   if (*passphrase)
-    err = agent_protect (buffer_new, passphrase, buffer, buffer_n, 0, -1);
+    err = agent_protect (buffer_new, passphrase, buffer, buffer_n, 0);
   else
     {
       /* The key derivation function does not support zero length
diff --git a/agent/command.c b/agent/command.c
index c113caba7..2e996d096 100644
--- a/agent/command.c
+++ b/agent/command.c
@@ -1218,12 +1218,6 @@ cmd_keyattr (assuan_context_t ctx, char *line)
   if (ctrl->restricted)
     return leave_cmd (ctx, gpg_error (GPG_ERR_FORBIDDEN));
 
-  if (!opt.enable_extended_key_format)
-    {
-      err = gpg_error (GPG_ERR_NOT_SUPPORTED);
-      goto leave;
-    }
-
   opt_delete = has_option (line, "--delete");
 
   line = skip_options (line);
@@ -2910,7 +2904,7 @@ cmd_import_key (assuan_context_t ctx, char *line)
   if (passphrase)
     {
       err = agent_protect (key, passphrase, &finalkey, &finalkeylen,
-                           ctrl->s2k_count, -1);
+                           ctrl->s2k_count);
       if (!err)
         err = agent_write_private_key (grip, finalkey, finalkeylen, force,
                                        NULL, NULL, opt_timestamp);
diff --git a/agent/cvt-openpgp.c b/agent/cvt-openpgp.c
index d170fdedc..9bb815ff8 100644
--- a/agent/cvt-openpgp.c
+++ b/agent/cvt-openpgp.c
@@ -1146,7 +1146,7 @@ convert_from_openpgp_native (ctrl_t ctrl,
 
           if (!agent_protect (*r_key, passphrase,
                               &protectedkey, &protectedkeylen,
-                              ctrl->s2k_count, -1))
+                              ctrl->s2k_count))
             agent_write_private_key (grip, protectedkey, protectedkeylen, 1,
                                      NULL, NULL, 0);
           xfree (protectedkey);
diff --git a/agent/findkey.c b/agent/findkey.c
index 060cb786d..098d5224f 100644
--- a/agent/findkey.c
+++ b/agent/findkey.c
@@ -2,6 +2,7 @@
  * Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007,
  *               2010, 2011 Free Software Foundation, Inc.
  * Copyright (C) 2014, 2019 Werner Koch
+ * Copyright (C) 2023 g10 Code GmbH
  *
  * This file is part of GnuPG.
  *
@@ -79,19 +80,114 @@ linefeed_to_percent0A (const char *string)
 }
 
 
-/* Note: Ownership of FNAME and FP are moved to this function.  */
-static gpg_error_t
-write_extended_private_key (char *fname, estream_t fp, int update, int newkey,
-                            const void *buf, size_t len,
-                            const char *serialno, const char *keyref,
-                            time_t timestamp)
+/* Write the S-expression formatted key (BUFFER,LENGTH) to our key
+ * storage.  With FORCE passed as true an existing key with the given
+ * GRIP will get overwritten.  If SERIALNO and KEYREF are given a
+ * Token line is added to the key if the extended format is used.  If
+ * TIMESTAMP is not zero and the key doies not yet exists it will be
+ * recorded as creation date.  */
+int
+agent_write_private_key (const unsigned char *grip,
+                         const void *buffer, size_t length, int force,
+                         const char *serialno, const char *keyref,
+                         time_t timestamp)
 {
   gpg_error_t err;
+  char *fname;
+  estream_t fp;
+  char hexgrip[40+4+1];
+  int update, newkey;
   nvc_t pk = NULL;
   gcry_sexp_t key = NULL;
   int remove = 0;
   char *token = NULL;
 
+  bin2hex (grip, 20, hexgrip);
+  strcpy (hexgrip+40, ".key");
+
+  fname = make_filename (gnupg_homedir (), GNUPG_PRIVATE_KEYS_DIR,
+                         hexgrip, NULL);
+
+  /* FIXME: Write to a temp file first so that write failures during
+     key updates won't lead to a key loss.  */
+
+  if (!force && !gnupg_access (fname, F_OK))
+    {
+      log_error ("secret key file '%s' already exists\n", fname);
+      xfree (fname);
+      return gpg_error (GPG_ERR_EEXIST);
+    }
+
+  fp = es_fopen (fname, force? "rb+,mode=-rw" : "wbx,mode=-rw");
+  if (!fp)
+    {
+      gpg_error_t tmperr = gpg_error_from_syserror ();
+
+      if (force && gpg_err_code (tmperr) == GPG_ERR_ENOENT)
+        {
+          fp = es_fopen (fname, "wbx,mode=-rw");
+          if (!fp)
+            tmperr = gpg_error_from_syserror ();
+        }
+      if (!fp)
+        {
+          log_error ("can't create '%s': %s\n", fname, gpg_strerror (tmperr));
+          xfree (fname);
+          return tmperr;
+        }
+      update = 0;
+      newkey = 1;
+    }
+  else if (force)
+    {
+      gpg_error_t rc;
+      char first;
+
+      /* See if an existing key is in extended format.  */
+      if (es_fread (&first, 1, 1, fp) != 1)
+        {
+          rc = gpg_error_from_syserror ();
+          log_error ("error reading first byte from '%s': %s\n",
+                     fname, strerror (errno));
+          xfree (fname);
+          es_fclose (fp);
+          return rc;
+        }
+
+      rc = es_fseek (fp, 0, SEEK_SET);
+      if (rc)
+        {
+          log_error ("error seeking in '%s': %s\n", fname, strerror (errno));
+          xfree (fname);
+          es_fclose (fp);
+          return rc;
+        }
+
+      if (first == '(')
+        {
+          /* Key is still in the old format - force it into extended
+           * format.  We do not request an update here because an
+           * existing key is not yet in extended key format and no
+           * extended infos are yet available.  */
+          update = 0;
+          newkey = 0;
+        }
+      else
+        {
+          /* Key is already in the extended format.  */
+          update = 1;
+          newkey = 0;
+        }
+    }
+  else
+    {
+      /* The key file did not exist: we assume this is a new key and
+       * write the Created: entry.  */
+      update = 0;
+      newkey = 1;
+    }
+
+
   if (update)
     {
       int line;
@@ -115,10 +211,11 @@ write_extended_private_key (char *fname, estream_t fp, int update, int newkey,
     }
   es_clearerr (fp);
 
-  err = gcry_sexp_sscan (&key, NULL, buf, len);
+  /* Turn (BUFFER,LENGTH) into a gcrypt s-expression and set it into
+   * our name value container.  */
+  err = gcry_sexp_sscan (&key, NULL, buffer, length);
   if (err)
     goto leave;
-
   err = nvc_set_private_key (pk, key);
   if (err)
     goto leave;
@@ -153,7 +250,7 @@ write_extended_private_key (char *fname, estream_t fp, int update, int newkey,
         }
     }
 
-  /* If a timestamp has been supplied and the key is new write a
+  /* If a timestamp has been supplied and the key is new, write a
    * creation timestamp.  (We douple check that there is no Created
    * item yet.)*/
   if (timestamp && newkey && !nvc_lookup (pk, "Created:"))
@@ -166,7 +263,7 @@ write_extended_private_key (char *fname, estream_t fp, int update, int newkey,
         goto leave;
     }
 
-
+  /* Back to start and write.  */
   err = es_fseek (fp, 0, SEEK_SET);
   if (err)
     goto leave;
@@ -212,133 +309,6 @@ write_extended_private_key (char *fname, estream_t fp, int update, int newkey,
   return err;
 }
 
-/* Write an S-expression formatted key to our key storage.  With FORCE
- * passed as true an existing key with the given GRIP will get
- * overwritten.  If SERIALNO and KEYREF are given a Token line is
- * added to the key if the extended format is used.  If TIMESTAMP is
- * not zero and the key doies not yet exists it will be recorded as
- * creation date.  */
-int
-agent_write_private_key (const unsigned char *grip,
-                         const void *buffer, size_t length, int force,
-                         const char *serialno, const char *keyref,
-                         time_t timestamp)
-{
-  char *fname;
-  estream_t fp;
-  char hexgrip[40+4+1];
-
-  bin2hex (grip, 20, hexgrip);
-  strcpy (hexgrip+40, ".key");
-
-  fname = make_filename (gnupg_homedir (), GNUPG_PRIVATE_KEYS_DIR,
-                         hexgrip, NULL);
-
-  /* FIXME: Write to a temp file first so that write failures during
-     key updates won't lead to a key loss.  */
-
-  if (!force && !gnupg_access (fname, F_OK))
-    {
-      log_error ("secret key file '%s' already exists\n", fname);
-      xfree (fname);
-      return gpg_error (GPG_ERR_EEXIST);
-    }
-
-  fp = es_fopen (fname, force? "rb+,mode=-rw" : "wbx,mode=-rw");
-  if (!fp)
-    {
-      gpg_error_t tmperr = gpg_error_from_syserror ();
-
-      if (force && gpg_err_code (tmperr) == GPG_ERR_ENOENT)
-        {
-          fp = es_fopen (fname, "wbx,mode=-rw");
-          if (!fp)
-            tmperr = gpg_error_from_syserror ();
-        }
-      if (!fp)
-        {
-          log_error ("can't create '%s': %s\n", fname, gpg_strerror (tmperr));
-          xfree (fname);
-          return tmperr;
-        }
-    }
-  else if (force)
-    {
-      gpg_error_t rc;
-      char first;
-
-      /* See if an existing key is in extended format.  */
-      if (es_fread (&first, 1, 1, fp) != 1)
-        {
-          rc = gpg_error_from_syserror ();
-          log_error ("error reading first byte from '%s': %s\n",
-                     fname, strerror (errno));
-          xfree (fname);
-          es_fclose (fp);
-          return rc;
-        }
-
-      rc = es_fseek (fp, 0, SEEK_SET);
-      if (rc)
-        {
-          log_error ("error seeking in '%s': %s\n", fname, strerror (errno));
-          xfree (fname);
-          es_fclose (fp);
-          return rc;
-        }
-
-      if (first != '(')
-        {
-          /* Key is already in the extended format.  */
-          return write_extended_private_key (fname, fp, 1, 0, buffer, length,
-                                             serialno, keyref, timestamp);
-        }
-      if (first == '(' && opt.enable_extended_key_format)
-        {
-          /* Key is in the old format - but we want the extended format.  */
-          return write_extended_private_key (fname, fp, 0, 0, buffer, length,
-                                             serialno, keyref, timestamp);
-        }
-    }
-
-  if (opt.enable_extended_key_format)
-    return write_extended_private_key (fname, fp, 0, 1, buffer, length,
-                                       serialno, keyref, timestamp);
-
-  if (es_fwrite (buffer, length, 1, fp) != 1)
-    {
-      gpg_error_t tmperr = gpg_error_from_syserror ();
-      log_error ("error writing '%s': %s\n", fname, gpg_strerror (tmperr));
-      es_fclose (fp);
-      gnupg_remove (fname);
-      xfree (fname);
-      return tmperr;
-    }
-
-  /* When force is given, the file might have to be truncated.  */
-  if (force && ftruncate (es_fileno (fp), es_ftello (fp)))
-    {
-      gpg_error_t tmperr = gpg_error_from_syserror ();
-      log_error ("error truncating '%s': %s\n", fname, gpg_strerror (tmperr));
-      es_fclose (fp);
-      gnupg_remove (fname);
-      xfree (fname);
-      return tmperr;
-    }
-
-  if (es_fclose (fp))
-    {
-      gpg_error_t tmperr = gpg_error_from_syserror ();
-      log_error ("error closing '%s': %s\n", fname, gpg_strerror (tmperr));
-      gnupg_remove (fname);
-      xfree (fname);
-      return tmperr;
-    }
-  bump_key_eventcounter ();
-  xfree (fname);
-  return 0;
-}
-
 
 gpg_error_t
 agent_update_private_key (const unsigned char *grip, nvc_t pk)
@@ -393,6 +363,7 @@ agent_update_private_key (const unsigned char *grip, nvc_t pk)
   return err;
 }
 
+
 /* Callback function to try the unprotection from the passphrase query
    code. */
 static gpg_error_t
diff --git a/agent/genkey.c b/agent/genkey.c
index eb6791dca..7660443ca 100644
--- a/agent/genkey.c
+++ b/agent/genkey.c
@@ -57,7 +57,7 @@ store_key (gcry_sexp_t private, const char *passphrase, int force,
     {
       unsigned char *p;
 
-      rc = agent_protect (buf, passphrase, &p, &len, s2k_count, -1);
+      rc = agent_protect (buf, passphrase, &p, &len, s2k_count);
       if (rc)
         {
           xfree (buf);
diff --git a/agent/gpg-agent.c b/agent/gpg-agent.c
index 381999cea..1db422737 100644
--- a/agent/gpg-agent.c
+++ b/agent/gpg-agent.c
@@ -116,8 +116,6 @@ enum cmd_and_opt_values
   oCheckSymPassphrasePattern,
   oMaxPassphraseDays,
   oEnablePassphraseHistory,
-  oDisableExtendedKeyFormat,
-  oEnableExtendedKeyFormat,
   oStealSocket,
   oUseStandardSocket,
   oNoUseStandardSocket,
@@ -238,8 +236,6 @@ static gpgrt_opt_t opts[] = {
                 /* */           "@"
 #endif
                 ),
-  ARGPARSE_s_n (oDisableExtendedKeyFormat, "disable-extended-key-format", "@"),
-  ARGPARSE_s_n (oEnableExtendedKeyFormat, "enable-extended-key-format", "@"),
   ARGPARSE_s_i (oListenBacklog, "listen-backlog", "@"),
   ARGPARSE_op_u (oAutoExpandSecmem, "auto-expand-secmem", "@"),
   ARGPARSE_s_s (oFakedSystemTime, "faked-system-time", "@"),
@@ -315,7 +311,8 @@ static gpgrt_opt_t opts[] = {
   ARGPARSE_s_n (oNoUseStandardSocket, "no-use-standard-socket", "@"),
 
   /* Dummy options.  */
-
+  ARGPARSE_s_n (oNoop, "disable-extended-key-format", "@"),
+  ARGPARSE_s_n (oNoop, "enable-extended-key-format", "@"),
 
   ARGPARSE_end () /* End of list */
 };
@@ -885,7 +882,6 @@ parse_rereadable_options (gpgrt_argparse_t *pargs, int reread)
       opt.check_sym_passphrase_pattern = NULL;
       opt.max_passphrase_days = MAX_PASSPHRASE_DAYS;
       opt.enable_passphrase_history = 0;
-      opt.enable_extended_key_format = 1;
       opt.ignore_cache_for_signing = 0;
       opt.allow_mark_trusted = 1;
       opt.sys_trustlist_name = NULL;
@@ -974,14 +970,6 @@ parse_rereadable_options (gpgrt_argparse_t *pargs, int reread)
       opt.enable_passphrase_history = 1;
       break;
 
-    case oEnableExtendedKeyFormat:
-      opt.enable_extended_key_format = 2;
-      break;
-    case oDisableExtendedKeyFormat:
-      if (opt.enable_extended_key_format != 2)
-        opt.enable_extended_key_format = 0;
-      break;
-
     case oIgnoreCacheForSigning: opt.ignore_cache_for_signing = 1; break;
 
     case oAllowMarkTrusted: opt.allow_mark_trusted = 1; break;
diff --git a/agent/protect-tool.c b/agent/protect-tool.c
index bb17033a8..87cf36814 100644
--- a/agent/protect-tool.c
+++ b/agent/protect-tool.c
@@ -97,7 +97,6 @@ static const char *opt_passphrase;
 static char *opt_prompt;
 static int opt_status_msg;
 static const char *opt_agent_program;
-static int opt_debug_use_ocb;
 
 static char *get_passphrase (int promptno);
 static void release_passphrase (char *pw);
@@ -343,8 +342,7 @@ read_and_protect (const char *fname)
     return;
 
   pw = get_passphrase (1);
-  rc = agent_protect (key, pw, &result, &resultlen, 0,
-                      opt_debug_use_ocb? 1 : -1);
+  rc = agent_protect (key, pw, &result, &resultlen, 0);
   release_passphrase (pw);
   xfree (key);
   if (rc)
@@ -610,7 +608,7 @@ main (int argc, char **argv )
         case oHaveCert: opt_have_cert = 1; break;
         case oPrompt: opt_prompt = pargs.r.ret_str; break;
         case oStatusMsg: opt_status_msg = 1; break;
-        case oDebugUseOCB: opt_debug_use_ocb = 1; break;
+        case oDebugUseOCB: /* dummy */; break;
 
         default: pargs.err = ARGPARSE_PRINT_ERROR; break;
 	}
diff --git a/agent/protect.c b/agent/protect.c
index 1084ee208..7197cf7e6 100644
--- a/agent/protect.c
+++ b/agent/protect.c
@@ -379,12 +379,11 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
                const char *passphrase,
                const char *timestamp_exp, size_t timestamp_exp_len,
                unsigned char **result, size_t *resultlen,
-	       unsigned long s2k_count, int use_ocb)
+	       unsigned long s2k_count)
 {
   gcry_cipher_hd_t hd;
   const char *modestr;
-  unsigned char hashvalue[20];
-  int blklen, enclen, outlen;
+  int enclen, outlen;
   unsigned char *iv = NULL;
   unsigned int ivsize;  /* Size of the buffer allocated for IV.  */
   const unsigned char *s2ksalt; /* Points into IV.  */
@@ -398,44 +397,26 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
   *resultlen = 0;
   *result = NULL;
 
-  modestr = (use_ocb? "openpgp-s2k3-ocb-aes"
-             /*   */: "openpgp-s2k3-sha1-" PROT_CIPHER_STRING "-cbc");
+  modestr = "openpgp-s2k3-ocb-aes";
 
   rc = gcry_cipher_open (&hd, PROT_CIPHER,
-                         use_ocb? GCRY_CIPHER_MODE_OCB :
-                         GCRY_CIPHER_MODE_CBC,
+                         GCRY_CIPHER_MODE_OCB,
                          GCRY_CIPHER_SECURE);
   if (rc)
     return rc;
 
   /* We need to work on a copy of the data because this makes it
    * easier to add the trailer and the padding and more important we
-   * have to prefix the text with 2 parenthesis.  In CBC mode we
-   * have to allocate enough space for:
-   *
-   *   ((<parameter_list>)(4:hash4:sha120:<hashvalue>)) + padding
-   *
-   * we always append a full block of random bytes as padding but
-   * encrypt only what is needed for a full blocksize.  In OCB mode we
+   * have to prefix the text with 2 parenthesis.  Due to OCB mode we
    * have to allocate enough space for just:
    *
    *   ((<parameter_list>))
    */
-  blklen = gcry_cipher_get_algo_blklen (PROT_CIPHER);
-  if (use_ocb)
-    {
-      /*       ((            )) */
-      outlen = 2 + protlen + 2 ;
-      enclen = outlen + 16 /* taglen */;
-      outbuf = gcry_malloc_secure (enclen);
-    }
-  else
-    {
-      /*       ((            )( 4:hash 4:sha1 20:<hash> ))  <padding>  */
-      outlen = 2 + protlen + 2 + 6   + 6    + 23      + 2 + blklen;
-      enclen = outlen/blklen * blklen;
-      outbuf = gcry_malloc_secure (outlen);
-    }
+
+  /*       ((            )) */
+  outlen = 2 + protlen + 2 ;
+  enclen = outlen + 16 /* taglen */;
+  outbuf = gcry_malloc_secure (enclen);
   if (!outbuf)
     {
       rc = out_of_core ();
@@ -445,10 +426,10 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
   /* Allocate a buffer for the nonce and the salt.  */
   if (!rc)
     {
-      /* Allocate random bytes to be used as IV, padding and s2k salt
-       * or in OCB mode for a nonce and the s2k salt.  The IV/nonce is
-       * set later because for OCB we need to set the key first.  */
-      ivsize = (use_ocb? 12 : (blklen*2)) + 8;
+      /* Allocate random bytes to be used as nonce and s2k salt.  The
+       * nonce is set later because for OCB we need to set the key
+       * first.  */
+      ivsize = 12 + 8;
       iv = xtrymalloc (ivsize);
       if (!iv)
         rc = gpg_error_from_syserror ();
@@ -484,40 +465,17 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
     goto leave;
 
   /* Set the IV/nonce.  */
-  rc = gcry_cipher_setiv (hd, iv, use_ocb? 12 : blklen);
+  rc = gcry_cipher_setiv (hd, iv, 12);
   if (rc)
     goto leave;
 
-  if (use_ocb)
-    {
-      /* In OCB Mode we use only the public key parameters as AAD.  */
-      rc = gcry_cipher_authenticate (hd, hashbegin, protbegin - hashbegin);
-      if (!rc)
-        rc = gcry_cipher_authenticate (hd, timestamp_exp, timestamp_exp_len);
-      if (!rc)
-        rc = gcry_cipher_authenticate
-          (hd, protbegin+protlen, hashlen - (protbegin+protlen - hashbegin));
-    }
-  else
-    {
-      /* Hash the entire expression for CBC mode.  Because
-       * TIMESTAMP_EXP won't get protected, we can't simply hash a
-       * continuous buffer but need to call md_write several times.  */
-      gcry_md_hd_t md;
-
-      rc = gcry_md_open (&md, GCRY_MD_SHA1, 0 );
-      if (!rc)
-        {
-          gcry_md_write (md, hashbegin, protbegin - hashbegin);
-          gcry_md_write (md, protbegin, protlen);
-          gcry_md_write (md, timestamp_exp, timestamp_exp_len);
-          gcry_md_write (md, protbegin+protlen,
-                         hashlen - (protbegin+protlen - hashbegin));
-          memcpy (hashvalue, gcry_md_read (md, GCRY_MD_SHA1), 20);
-          gcry_md_close (md);
-        }
-    }
-
+  /* In OCB Mode we use only the public key parameters as AAD.  */
+  rc = gcry_cipher_authenticate (hd, hashbegin, protbegin - hashbegin);
+  if (!rc)
+    rc = gcry_cipher_authenticate (hd, timestamp_exp, timestamp_exp_len);
+  if (!rc)
+    rc = gcry_cipher_authenticate
+      (hd, protbegin+protlen, hashlen - (protbegin+protlen - hashbegin));
 
   /* Encrypt.  */
   if (!rc)
@@ -527,36 +485,15 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
       *p++ = '(';
       memcpy (p, protbegin, protlen);
       p += protlen;
-      if (use_ocb)
-        {
-          *p++ = ')';
-          *p++ = ')';
-        }
-      else
-        {
-          memcpy (p, ")(4:hash4:sha120:", 17);
-          p += 17;
-          memcpy (p, hashvalue, 20);
-          p += 20;
-          *p++ = ')';
-          *p++ = ')';
-          memcpy (p, iv+blklen, blklen); /* Add padding.  */
-          p += blklen;
-        }
+      *p++ = ')';
+      *p++ = ')';
       log_assert ( p - outbuf == outlen);
-      if (use_ocb)
-        {
-          gcry_cipher_final (hd);
-          rc = gcry_cipher_encrypt (hd, outbuf, outlen, NULL, 0);
-          if (!rc)
-            {
-              log_assert (outlen + 16 == enclen);
-              rc = gcry_cipher_gettag (hd, outbuf + outlen, 16);
-            }
-        }
-      else
+      gcry_cipher_final (hd);
+      rc = gcry_cipher_encrypt (hd, outbuf, outlen, NULL, 0);
+      if (!rc)
         {
-          rc = gcry_cipher_encrypt (hd, outbuf, enclen, NULL, 0);
+          log_assert (outlen + 16 == enclen);
+          rc = gcry_cipher_gettag (hd, outbuf + outlen, 16);
         }
     }
 
@@ -584,7 +521,7 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
        (int)strlen (modestr), modestr,
        &saltpos,
        (unsigned int)strlen (countbuf), countbuf,
-       use_ocb? 12 : blklen, &ivpos, use_ocb? 12 : blklen, "",
+       12, &ivpos, 12, "",
        enclen, &encpos, enclen, "");
     if (!p)
       {
@@ -598,7 +535,7 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
   *resultlen = strlen (p);
   *result = (unsigned char*)p;
   memcpy (p+saltpos, s2ksalt, 8);
-  memcpy (p+ivpos, iv, use_ocb? 12 : blklen);
+  memcpy (p+ivpos, iv, 12);
   memcpy (p+encpos, outbuf, enclen);
   xfree (iv);
   xfree (outbuf);
@@ -614,13 +551,11 @@ do_encryption (const unsigned char *hashbegin, size_t hashlen,
 
 
 /* Protect the key encoded in canonical format in PLAINKEY.  We assume
-   a valid S-Exp here.  With USE_UCB set to -1 the default scheme is
-   used (ie. either CBC or OCB), set to 0 the old CBC mode is used,
-   and set to 1 OCB is used. */
+ * a valid S-Exp here.  */
 int
 agent_protect (const unsigned char *plainkey, const char *passphrase,
                unsigned char **result, size_t *resultlen,
-	       unsigned long s2k_count, int use_ocb)
+	       unsigned long s2k_count)
 {
   int rc;
   const char *parmlist;
@@ -637,9 +572,6 @@ agent_protect (const unsigned char *plainkey, const char *passphrase,
   unsigned char *p;
   int have_curve = 0;
 
-  if (use_ocb == -1)
-    use_ocb = !!opt.enable_extended_key_format;
-
   /* Create an S-expression with the protected-at timestamp.  */
   memcpy (timestamp_exp, "(12:protected-at15:", 19);
   gnupg_get_isotime (timestamp_exp+19);
@@ -743,7 +675,7 @@ agent_protect (const unsigned char *plainkey, const char *passphrase,
   rc = do_encryption (hash_begin, hash_end - hash_begin + 1,
                       prot_begin, prot_end - prot_begin + 1,
                       passphrase, timestamp_exp, sizeof (timestamp_exp),
-                      &protected, &protectedlen, s2k_count, use_ocb);
+                      &protected, &protectedlen, s2k_count);
   if (rc)
     return rc;
 
diff --git a/agent/t-protect.c b/agent/t-protect.c
index 88b552585..e6edbffba 100644
--- a/agent/t-protect.c
+++ b/agent/t-protect.c
@@ -196,7 +196,7 @@ test_agent_protect (void)
     {
       ret = agent_protect ((const unsigned char*)specs[i].key,
                            specs[i].passphrase,
-			   &specs[i].result, &specs[i].resultlen, 0, -1);
+			   &specs[i].result, &specs[i].resultlen, 0);
       if (gpg_err_code (ret) != specs[i].ret_expected)
 	{
 	  printf ("agent_protect(%d) returned '%i/%s'; expected '%i/%s'\n",
diff --git a/doc/gpg-agent.texi b/doc/gpg-agent.texi
index 921522d53..1a03de010 100644
--- a/doc/gpg-agent.texi
+++ b/doc/gpg-agent.texi
@@ -615,15 +615,11 @@ remote machine.
 @itemx --disable-extended-key-format
 @opindex enable-extended-key-format
 @opindex disable-extended-key-format
-Since version 2.3 keys are created in the extended private key format.
-Changing the passphrase of a key will also convert the key to that new
-format.  This new key format is supported since GnuPG version 2.1.12
-and thus there should be no need to disable it.  The disable option
-allows to revert to the old behavior for new keys; be aware that keys
-are never migrated back to the old format.  However if the enable
-option has been used the disable option won't have an effect.  The
-advantage of the extended private key format is that it is text based
-and can carry additional meta data.
+These options are obsolete and have no effect.  The extended key format
+is used for years now and has been supported since 2.1.12.  Existing
+keys in the old format are migrated to the new format as soon as they
+are touched.
+
 
 @anchor{option --enable-ssh-support}
 @item --enable-ssh-support