gpg: Remove MDC options

* g10/gpg.c: Tuen options --force-mdc, --no-force-mdc, --disable-mdc
and --no-disable-mdc into NOPs.
* g10/encrypt.c (use_mdc): Simplify.  MDC is now almost always used.
(use_aead): Ignore MDC options. Print warning for missing MDC feature
flags.
* g10/pkclist.c (warn_missing_mdc_from_pklist): Rename to ...
(warn_missing_aead_from_pklist): this and adjust.
--

The MDC is now always used except with --rfc2440 which will lead to a
a big fat warning.

Signed-off-by: Werner Koch <wk@gnupg.org>

5 files changed, 29 insertions, 74 deletions

diff --git a/g10/cipher-cfb.c b/g10/cipher-cfb.c
index 48927c558..3ba8eb738 100644
--- a/g10/cipher-cfb.c
+++ b/g10/cipher-cfb.c
@@ -33,6 +33,7 @@
 #include "packet.h"
 #include "options.h"
 #include "main.h"
+#include "../common/i18n.h"
 #include "../common/status.h"
 
 
@@ -66,8 +67,9 @@ write_header (cipher_filter_context_t *cfx, iobuf_t a)
     }
   else
     {
-      log_info ("WARNING: "
-                "encrypting without integrity protection is dangerous\n");
+      log_info (_("WARNING: "
+                  "encrypting without integrity protection is dangerous\n"));
+      log_info (_("Hint: Do not use option %s\n"), "--rfc2440");
     }
 
   write_status_printf (STATUS_BEGIN_ENCRYPTION, "%d %d",
diff --git a/g10/encrypt.c b/g10/encrypt.c
index c6c9e3a03..7de07d234 100644
--- a/g10/encrypt.c
+++ b/g10/encrypt.c
@@ -212,11 +212,7 @@ use_aead (pk_list_t pk_list, int algo)
 
   can_use = openpgp_cipher_get_algo_blklen (algo) == 16;
 
-  /* With --force-mdc we clearly do not want AEAD.  */
-  if (opt.force_mdc)
-    return 0;
-
-  /* However with --force-aead we want AEAD.  */
+  /* With --force-aead we want AEAD.  */
   if (opt.force_aead)
     {
       if (!can_use)
@@ -232,62 +228,29 @@ use_aead (pk_list_t pk_list, int algo)
   if (!can_use)
     return 0;
 
+  /* Note the user which keys have no AEAD feature flag set.  */
+  if (opt.verbose)
+    warn_missing_aead_from_pklist (pk_list);
+
   /* If all keys support AEAD we can use it.  */
   return select_aead_from_pklist (pk_list);
 }
 
 
-/* We try very hard to use a MDC */
+/* Shall we use the MDC?  Yes - unless rfc-2440 compatibility is
+ * requested. */
 int
 use_mdc (pk_list_t pk_list,int algo)
 {
-  /* RFC-2440 don't has MDC */
-  if (RFC2440)
-    return 0;
-
-  /* --force-mdc overrides --disable-mdc */
-  if(opt.force_mdc)
-    return 1;
+  (void)pk_list;
+  (void)algo;
 
-  if(opt.disable_mdc)
+  /* RFC-2440 don't has MDC - this is the only way to create a legacy
+   * non-MDC encryption packet.  */
+  if (RFC2440)
     return 0;
 
-  /* Do the keys really support MDC? */
-
-  if(select_mdc_from_pklist(pk_list))
-    return 1;
-
-  /* The keys don't support MDC, so now we do a bit of a hack - if any
-     of the AESes or TWOFISH are in the prefs, we assume that the user
-     can handle a MDC.  This is valid for PGP 7, which can handle MDCs
-     though it will not generate them.  2440bis allows this, by the
-     way. */
-
-  if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
-			    CIPHER_ALGO_AES,NULL)==CIPHER_ALGO_AES)
-    return 1;
-
-  if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
-			    CIPHER_ALGO_AES192,NULL)==CIPHER_ALGO_AES192)
-    return 1;
-
-  if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
-			    CIPHER_ALGO_AES256,NULL)==CIPHER_ALGO_AES256)
-    return 1;
-
-  if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
-			    CIPHER_ALGO_TWOFISH,NULL)==CIPHER_ALGO_TWOFISH)
-    return 1;
-
-  /* Last try.  Use MDC for the modern ciphers. */
-
-  if (openpgp_cipher_get_algo_blklen (algo) != 8)
-    return 1;
-
-  if (opt.verbose)
-    warn_missing_mdc_from_pklist (pk_list);
-
-  return 0; /* No MDC */
+  return 1; /* In all other cases we use the MDC */
 }
 
 
diff --git a/g10/gpg.c b/g10/gpg.c
index e718fe45e..1a419f7e7 100644
--- a/g10/gpg.c
+++ b/g10/gpg.c
@@ -301,10 +301,6 @@ enum cmd_and_opt_values
     oShowPhotos,
     oNoShowPhotos,
     oPhotoViewer,
-    oForceMDC,
-    oNoForceMDC,
-    oDisableMDC,
-    oNoDisableMDC,
     oForceAEAD,
     oS2KMode,
     oS2KDigest,
@@ -605,11 +601,6 @@ static ARGPARSE_OPTS opts[] = {
   ARGPARSE_s_n (oQuiet,	  "quiet",   "@"),
   ARGPARSE_s_n (oNoTTY,   "no-tty",  "@"),
 
-  ARGPARSE_s_n (oForceMDC, "force-mdc", "@"),
-  ARGPARSE_s_n (oNoForceMDC, "no-force-mdc", "@"),
-  ARGPARSE_s_n (oDisableMDC, "disable-mdc", "@"),
-  ARGPARSE_s_n (oNoDisableMDC, "no-disable-mdc", "@"),
-
   ARGPARSE_s_n (oForceAEAD, "force-aead", "@"),
 
   ARGPARSE_s_n (oDisableSignerUID, "disable-signer-uid", "@"),
@@ -924,6 +915,11 @@ static ARGPARSE_OPTS opts[] = {
   ARGPARSE_s_n (oNoop, "force-v4-certs", "@"),
   ARGPARSE_s_n (oNoop, "no-force-v4-certs", "@"),
   ARGPARSE_s_n (oNoop, "no-mdc-warning", "@"),
+  ARGPARSE_s_n (oNoop, "force-mdc", "@"),
+  ARGPARSE_s_n (oNoop, "no-force-mdc", "@"),
+  ARGPARSE_s_n (oNoop, "disable-mdc", "@"),
+  ARGPARSE_s_n (oNoop, "no-disable-mdc", "@"),
+
 
   ARGPARSE_end ()
 };
@@ -2201,7 +2197,6 @@ set_compliance_option (enum cmd_and_opt_values option)
     case oDE_VS:
       set_compliance_option (oOpenPGP);
       opt.compliance = CO_DE_VS;
-      opt.force_mdc = 1;
       opt.def_aead_algo = 0;
       /* Fixme: Change other options.  */
       break;
@@ -3019,11 +3014,6 @@ main (int argc, char **argv)
 	    break;
 	  case oPhotoViewer: opt.photo_viewer = pargs.r.ret_str; break;
 
-	  case oForceMDC: opt.force_mdc = 1; break;
-	  case oNoForceMDC: opt.force_mdc = 0; break;
-	  case oDisableMDC: opt.disable_mdc = 1; break;
-	  case oNoDisableMDC: opt.disable_mdc = 0; break;
-
 	  case oForceAEAD: opt.force_aead = 1; break;
 
           case oDisableSignerUID: opt.flags.disable_signer_uid = 1; break;
@@ -3802,7 +3792,6 @@ main (int argc, char **argv)
       {
         /* That does not anymore work because we have no more support
            for v3 signatures.  */
-	opt.disable_mdc=1;
 	opt.escape_from=1;
 	opt.ask_sig_expire=0;
       }
diff --git a/g10/keydb.h b/g10/keydb.h
index c65af0204..bd156a6a3 100644
--- a/g10/keydb.h
+++ b/g10/keydb.h
@@ -236,7 +236,7 @@ int  select_algo_from_prefs( PK_LIST pk_list, int preftype,
 			     int request, const union pref_hint *hint);
 int  select_mdc_from_pklist (PK_LIST pk_list);
 aead_algo_t select_aead_from_pklist (pk_list_t pk_list);
-void warn_missing_mdc_from_pklist (PK_LIST pk_list);
+void warn_missing_aead_from_pklist (PK_LIST pk_list);
 void warn_missing_aes_from_pklist (PK_LIST pk_list);
 
 /*-- skclist.c --*/
diff --git a/g10/pkclist.c b/g10/pkclist.c
index 8b5d0422a..05bbea52d 100644
--- a/g10/pkclist.c
+++ b/g10/pkclist.c
@@ -1677,9 +1677,10 @@ select_aead_from_pklist (PK_LIST pk_list)
 }
 
 
-/* Print a warning for all keys in PK_LIST missing the MDC feature. */
+/* Print a warning for all keys in PK_LIST missing the AEAD feature
+ * flag or AEAD algorithms. */
 void
-warn_missing_mdc_from_pklist (PK_LIST pk_list)
+warn_missing_aead_from_pklist (PK_LIST pk_list)
 {
   PK_LIST pkr;
 
@@ -1688,12 +1689,12 @@ warn_missing_mdc_from_pklist (PK_LIST pk_list)
       int mdc;
 
       if (pkr->pk->user_id) /* selected by user ID */
-        mdc = pkr->pk->user_id->flags.mdc;
+        mdc = pkr->pk->user_id->flags.aead;
       else
-        mdc = pkr->pk->flags.mdc;
+        mdc = pkr->pk->flags.aead;
       if (!mdc)
         log_info (_("Note: key %s has no %s feature\n"),
-                  keystr_from_pk (pkr->pk), "MDC");
+                  keystr_from_pk (pkr->pk), "AEAD");
     }
 }