Add tweaks for the not anymore patented IDEA algorithm.

* g10/keygen.c (keygen_set_std_prefs): Include IDEA only in PGP2
compatibility mode.
* g10/misc.c (idea_cipher_warn): Remove.  Also remove all callers.
* common/status.h (STATUS_RSA_OR_IDEA): Remove.  Do not emit this
status anymore.
--

To keep the number of actually used algorithms low, we want to support
IDEA only in a basically read-only way (unless --pgp2 is used during
key generation).  It does not make sense to suggest the use of this
old 64 bit blocksize algorithm.  However, there is old data available
where it might be helpful to have IDEA available.

common/status.h

@@ -32,8 +32,6 @@ enum
 
     STATUS_BADARMOR,
 
-    STATUS_RSA_OR_IDEA,
-
     STATUS_TRUST_UNDEFINED,
     STATUS_TRUST_NEVER,
     STATUS_TRUST_MARGINAL,

doc/DETAILS

@@ -381,11 +381,9 @@ more arguments in future versions.
 	The ASCII armor is corrupted.  No arguments yet.
 
     RSA_OR_IDEA
-	The IDEA algorithms has been used in the data.  A
-	program might want to fallback to another program to handle
-	the data if GnuPG failed.  This status message used to be emitted
-        also for RSA but this has been dropped after the RSA patent expired.
-        However we can't change the name of the message.
+	Obsolete.  This status message used to be emitted for requests
+        to use the IDEA or RSA algorithms.  It has been dropped from
+        GnuPG 2.1 after the respective patents expired.
 
     SHM_INFO
     SHM_GET

g10/gpg.c

@@ -3149,7 +3149,6 @@ main (int argc, char **argv)
 	      {
 		log_info(_("encrypting a message in --pgp2 mode requires "
 			   "the IDEA cipher\n"));
-		idea_cipher_warn(1);
 		unusable=1;
 	      }
 	    else if(cmd==aSym)
@@ -3208,10 +3207,6 @@ main (int argc, char **argv)
 
     if( def_cipher_string ) {
 	opt.def_cipher_algo = string_to_cipher_algo (def_cipher_string);
-	if(opt.def_cipher_algo==0 &&
-	   (ascii_strcasecmp(def_cipher_string,"idea")==0
-	    || ascii_strcasecmp(def_cipher_string,"s1")==0))
-	  idea_cipher_warn(1);
 	xfree(def_cipher_string); def_cipher_string = NULL;
 	if ( openpgp_cipher_test_algo (opt.def_cipher_algo) )
 	    log_error(_("selected cipher algorithm is invalid\n"));

g10/import.c

@@ -1434,12 +1434,6 @@ transfer_secret_keys (ctrl_t ctrl, struct stats_s *stats, kbnode_t sec_keyblock)
           log_error (_("key %s: error sending to agent: %s\n"),
                      keystr_from_pk_with_sub (main_pk, pk),
                      gpg_strerror (err));
-          if (ski->algo == GCRY_CIPHER_IDEA
-              && gpg_err_code (err) == GPG_ERR_CIPHER_ALGO)
-            {
-              write_status (STATUS_RSA_OR_IDEA);
-              idea_cipher_warn (0);
-            }
           if (gpg_err_code (err) == GPG_ERR_CANCELED
               || gpg_err_code (err) == GPG_ERR_FULLY_CANCELED)
             break; /* Don't try the other subkeys.  */

g10/keygen.c

@@ -349,7 +349,7 @@ keygen_set_std_prefs (const char *string,int personal)
 	       break PGP2, but that is difficult with the current
 	       code, and not really worth checking as a non-RSA <=2048
 	       bit key wouldn't be usable by PGP2 anyway. -dms */
-	    if ( !openpgp_cipher_test_algo (CIPHER_ALGO_IDEA) )
+	    if (PGP2 && !openpgp_cipher_test_algo (CIPHER_ALGO_IDEA) )
 	      strcat(dummy_string,"S1 ");
 
 
@@ -442,12 +442,6 @@ keygen_set_std_prefs (const char *string,int personal)
 	    else
 	      {
 		log_info (_("invalid item `%s' in preference string\n"),tok);
-
-		/* Complain if IDEA is not available. */
-		if(ascii_strcasecmp(tok,"s1")==0
-		   || ascii_strcasecmp(tok,"idea")==0)
-		  idea_cipher_warn(1);
-
 		rc=-1;
 	      }
 	  }

g10/main.h

@@ -105,12 +105,6 @@ int openpgp_md_test_algo( int algo );
 const char *openpgp_pk_algo_name (int algo);
 const char *openpgp_md_algo_name (int algo);
 
-#ifdef USE_IDEA
-void idea_cipher_warn( int show );
-#else
-#define idea_cipher_warn(a)  do { } while (0)
-#endif
-
 struct expando_args
 {
   PKT_public_key *pk;

g10/mainproc.c

@@ -250,12 +250,6 @@ symkey_decrypt_seskey( DEK *dek, byte *seskey, size_t slen )
   if(dek->keylen > DIM(dek->key))
     BUG ();
 
-  /* This is not completely accurate, since a bad passphrase may have
-     resulted in a garbage algorithm byte, but it's close enough since
-     a bogus byte here will fail later. */
-  if(dek->algo==CIPHER_ALGO_IDEA)
-    idea_cipher_warn(0);
-
   memcpy(dek->key, seskey + 1, dek->keylen);
 
   /*log_hexdump( "thekey", dek->key, dek->keylen );*/
@@ -541,7 +535,6 @@ proc_encrypted( CTX c, PACKET *pkt )
 		algo = opt.def_cipher_algo;
 		if (!algo)
 		  algo = opt.s2k_cipher_algo;
-		idea_cipher_warn(1);
 		log_info (_("IDEA cipher unavailable, "
 			    "optimistically attempting to use %s instead\n"),
 			  openpgp_cipher_algo_name (algo));

g10/misc.c

@@ -546,24 +546,6 @@ openpgp_md_algo_name (int algo)
 }
 
 
-#ifdef USE_IDEA
-/* Special warning for the IDEA cipher */
-void
-idea_cipher_warn(int show)
-{
-  static int warned=0;
-
-  if(!warned || show)
-    {
-      log_info(_("the IDEA cipher plugin is not present\n"));
-      log_info(_("please see %s for more information\n"),
-               "http://www.gnupg.org/faq/why-not-idea.html");
-      warned=1;
-    }
-}
-#endif
-
-
 static unsigned long
 get_signature_count (PKT_public_key *pk)
 {

g10/pubkey-enc.c

@@ -292,8 +292,6 @@ get_it (PKT_pubkey_enc *enc, DEK *dek, PKT_public_key *sk, u32 *keyid)
 
   dek->keylen = nframe - (n + 1) - 2;
   dek->algo = frame[n++];
-  if (dek->algo == CIPHER_ALGO_IDEA)
-    write_status (STATUS_RSA_OR_IDEA);
   err = openpgp_cipher_test_algo (dek->algo);
   if (err)
     {
@@ -302,8 +300,6 @@ get_it (PKT_pubkey_enc *enc, DEK *dek, PKT_public_key *sk, u32 *keyid)
           log_info (_("cipher algorithm %d%s is unknown or disabled\n"),
                     dek->algo,
                     dek->algo == CIPHER_ALGO_IDEA ? " (IDEA)" : "");
-          if (dek->algo == CIPHER_ALGO_IDEA)
-            idea_cipher_warn (0);
         }
       dek->algo = 0;
       goto leave;

g10/seckey-cert.c

@@ -62,11 +62,6 @@ xxxx_do_check( PKT_secret_key *sk, const char *tryagain_text, int mode,
 	if( openpgp_cipher_test_algo( sk->protect.algo ) ) {
 	    log_info(_("protection algorithm %d%s is not supported\n"),
 			sk->protect.algo,sk->protect.algo==1?" (IDEA)":"" );
-	    if (sk->protect.algo==CIPHER_ALGO_IDEA)
-              {
-                write_status (STATUS_RSA_OR_IDEA);
-                idea_cipher_warn (0);
-              }
 	    return G10ERR_CIPHER_ALGO;
 	}
 	if(gcry_md_test_algo (sk->protect.s2k.hash_algo))