gpg: Add configure options to disable algorithms

* acinclude.m4 (GNUPG_GPG_DISABLE_ALGO): New.
* configure.ac: Add --enable-gpg-* options to disable non MUS
algorithms.
* g10/misc.c (map_cipher_openpgp_to_gcry): Implement these options.
(openpgp_pk_test_algo2): Ditto.
(map_md_openpgp_to_gcry): Ditto.
(openpgp_cipher_test_algo, openpgp_md_test_algo): Simplify.
--

We have a similar feature in GnuPG-1.  Although we don't shrink the
size of the gpg binary by disabling algorithms (they are implemented
in Libgcrypt), this feature may still be useful for inerop testing.

3 files changed, 101 insertions, 28 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index a37e0f528..7c264a41b 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -7,12 +7,12 @@ dnl GnuPG is free software; you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
 dnl the Free Software Foundation; either version 3 of the License, or
 dnl (at your option) any later version.
-dnl 
+dnl
 dnl GnuPG is distributed in the hope that it will be useful,
 dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
 dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 dnl GNU General Public License for more details.
-dnl 
+dnl
 dnl You should have received a copy of the GNU General Public License
 dnl along with this program; if not, see <http://www.gnu.org/licenses/>.
 
@@ -38,7 +38,7 @@ AC_DEFUN([GNUPG_CHECK_TYPEDEF],
 dnl GNUPG_CHECK_GNUMAKE
 dnl
 AC_DEFUN([GNUPG_CHECK_GNUMAKE],
-  [ 
+  [
     if ${MAKE-make} --version 2>/dev/null | grep '^GNU ' >/dev/null 2>&1; then
         :
     else
@@ -59,7 +59,7 @@ AC_DEFUN([GNUPG_CHECK_FAQPROG],
     if faqprog.pl -V 2>/dev/null | grep '^faqprog.pl ' >/dev/null 2>&1; then
         working_faqprog=yes
         FAQPROG="faqprog.pl"
-    else 
+    else
 	working_faqprog=no
         FAQPROG=": "
     fi
@@ -77,7 +77,7 @@ dnl ***    ftp://ftp.gnupg.org/gcrypt/contrib/faqprog.pl )
 dnl *** No need to worry about this warning.
 dnl ***]])
 dnl     fi
-   ])       
+   ])
 
 dnl GNUPG_CHECK_DOCBOOK_TO_TEXI
 dnl
@@ -93,7 +93,7 @@ AC_DEFUN([GNUPG_CHECK_DOCBOOK_TO_TEXI],
     fi
     AC_MSG_RESULT($working_sgmltotexi)
     AM_CONDITIONAL(HAVE_DOCBOOK_TO_TEXI, test "$working_sgmltotexi" = "yes" )
-   ])       
+   ])
 
 
 
@@ -162,7 +162,7 @@ AC_DEFUN([GNUPG_CHECK_ENDIAN],
 # Add a --enable-NAME option to configure an set the
 # shell variable build_NAME either to "yes" or "no".  DEFAULT must
 # either be "yes" or "no" and decided on the default value for
-# build_NAME and whether --enable-NAME or --disable-NAME is shown with 
+# build_NAME and whether --enable-NAME or --disable-NAME is shown with
 # ./configure --help
 AC_DEFUN([GNUPG_BUILD_PROGRAM],
   [build_$1=$2
@@ -178,7 +178,7 @@ AC_DEFUN([GNUPG_BUILD_PROGRAM],
    case "$build_$1" in
          no|yes)
            ;;
-         *) 
+         *)
            AC_MSG_ERROR([only yes or no allowed for feature --enable-$1])
            ;;
    esac
@@ -186,6 +186,23 @@ AC_DEFUN([GNUPG_BUILD_PROGRAM],
 
 
 
+# GNUPG_DISABLE_GPG_ALGO(NAME,DESCRIPTION)
+#
+# Add a --disable-gpg-NAME option and the corresponding ac_define
+# GPG_USE_<NAME>.
+AC_DEFUN([GNUPG_GPG_DISABLE_ALGO],
+  [AC_MSG_CHECKING([whether to enable the $2 for gpg])
+   AC_ARG_ENABLE([gpg-$1], AC_HELP_STRING([--disable-gpg-$1],
+                                          [disable the $2 algorithm in gpg]),
+                                          , enableval=yes)
+   AC_MSG_RESULT($enableval)
+   if test x"$enableval" = xyes ; then
+     AC_DEFINE(GPG_USE_[]m4_toupper($1), 1, [Define to support the $2])
+   fi
+  ])
+
+
+
 
 # Check whether mlock is broken (hpux 10.20 raises a SIGBUS if mlock
 # is not called from uid 0 (not tested whether uid 0 works)
diff --git a/configure.ac b/configure.ac
index f4b2d388c..9476dc48b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -212,6 +212,39 @@ AC_ARG_ENABLE(selinux-support,
               selinux_support=$enableval, selinux_support=no)
 AC_MSG_RESULT($selinux_support)
 
+
+#
+# Options to disable algorithm
+#
+
+GNUPG_GPG_DISABLE_ALGO([rsa],[RSA public key])
+# Elgamal is a MUST algorithm
+# DSA is a MUST algorithm
+GNUPG_GPG_DISABLE_ALGO([ecdh],[ECDH public key])
+GNUPG_GPG_DISABLE_ALGO([ecdsa],[ECDSA public key])
+GNUPG_GPG_DISABLE_ALGO([eddsa],[EdDSA public key])
+
+GNUPG_GPG_DISABLE_ALGO([idea],[IDEA cipher])
+# 3DES is a MUST algorithm
+GNUPG_GPG_DISABLE_ALGO([cast5],[CAST5 cipher])
+GNUPG_GPG_DISABLE_ALGO([blowfish],[BLOWFISH cipher])
+GNUPG_GPG_DISABLE_ALGO([aes128],[AES128 cipher])
+GNUPG_GPG_DISABLE_ALGO([aes192],[AES192 cipher])
+GNUPG_GPG_DISABLE_ALGO([aes256],[AES256 cipher])
+GNUPG_GPG_DISABLE_ALGO([twofish],[TWOFISH cipher])
+GNUPG_GPG_DISABLE_ALGO([camellia128],[CAMELLIA128 cipher])
+GNUPG_GPG_DISABLE_ALGO([camellia192],[CAMELLIA192 cipher])
+GNUPG_GPG_DISABLE_ALGO([camellia256],[CAMELLIA256 cipher])
+
+GNUPG_GPG_DISABLE_ALGO([md5],[MD5 hash])
+# SHA1 is a MUSt algorithm
+GNUPG_GPG_DISABLE_ALGO([rmd160],[RIPE-MD160 hash])
+GNUPG_GPG_DISABLE_ALGO([sha224],[SHA-224 hash])
+GNUPG_GPG_DISABLE_ALGO([sha256],[SHA-256 hash])
+GNUPG_GPG_DISABLE_ALGO([sha384],[SHA-384 hash])
+GNUPG_GPG_DISABLE_ALGO([sha512],[SHA-512 hash])
+
+
 # Allow disabling of zip support.
 # This is in general not a good idea because according to rfc4880 OpenPGP
 # implementations SHOULD support ZLIB.
diff --git a/g10/misc.c b/g10/misc.c
index 6d3a7b82f..ef26a5aa3 100644
--- a/g10/misc.c
+++ b/g10/misc.c
@@ -348,17 +348,37 @@ map_cipher_openpgp_to_gcry (cipher_algo_t algo)
   switch (algo)
     {
     case CIPHER_ALGO_NONE:        return GCRY_CIPHER_NONE;
+#ifdef GPG_USE_IDEA
     case CIPHER_ALGO_IDEA:        return GCRY_CIPHER_IDEA;
+#endif
     case CIPHER_ALGO_3DES:	  return GCRY_CIPHER_3DES;
+#ifdef GPG_USE_CAST5
     case CIPHER_ALGO_CAST5:	  return GCRY_CIPHER_CAST5;
+#endif
+#ifdef GPG_USE_BLOWFISH
     case CIPHER_ALGO_BLOWFISH:    return GCRY_CIPHER_BLOWFISH;
+#endif
+#ifdef GPG_USE_AES128
     case CIPHER_ALGO_AES:         return GCRY_CIPHER_AES;
+#endif
+#ifdef GPG_USE_AES192
     case CIPHER_ALGO_AES192:      return GCRY_CIPHER_AES192;
+#endif
+#ifdef GPG_USE_AES256
     case CIPHER_ALGO_AES256:      return GCRY_CIPHER_AES256;
+#endif
+#ifdef GPG_USE_TWOFISH
     case CIPHER_ALGO_TWOFISH:     return GCRY_CIPHER_TWOFISH;
+#endif
+#ifdef GPG_USE_CAMELLIA128
     case CIPHER_ALGO_CAMELLIA128: return GCRY_CIPHER_CAMELLIA128;
+#endif
+#ifdef GPG_USE_CAMELLIA192
     case CIPHER_ALGO_CAMELLIA192: return GCRY_CIPHER_CAMELLIA192;
+#endif
+#ifdef GPG_USE_CAMELLIA256
     case CIPHER_ALGO_CAMELLIA256: return GCRY_CIPHER_CAMELLIA256;
+#endif
     }
   return 0;
 }
@@ -437,17 +457,6 @@ openpgp_cipher_test_algo (cipher_algo_t algo)
   enum gcry_cipher_algos ga;
 
   ga = map_cipher_openpgp_to_gcry (algo);
-
-  /* Use this explicit list to disable certain algorithms. */
-  switch (algo)
-    {
-    /* case CIPHER_ALGO_IDEA:         */
-    /*   ga = 0; */
-    /*   break; */
-    default:
-      break;
-    }
-
   if (!ga)
     return gpg_error (GPG_ERR_CIPHER_ALGO);
 
@@ -497,15 +506,23 @@ openpgp_pk_test_algo2 (pubkey_algo_t algo, unsigned int use)
 
   switch (algo)
     {
+#ifdef GPG_USE_RSA
     case PUBKEY_ALGO_RSA:       ga = GCRY_PK_RSA;   break;
     case PUBKEY_ALGO_RSA_E:     ga = GCRY_PK_RSA_E; break;
     case PUBKEY_ALGO_RSA_S:     ga = GCRY_PK_RSA_S; break;
+#endif
     case PUBKEY_ALGO_ELGAMAL_E: ga = GCRY_PK_ELG;   break;
     case PUBKEY_ALGO_DSA:       ga = GCRY_PK_DSA;   break;
 
-    case PUBKEY_ALGO_ECDH:
-    case PUBKEY_ALGO_ECDSA:
+#ifdef GPG_USE_ECDH
+    case PUBKEY_ALGO_ECDH:      ga = GCRY_PK_ECC;   break;
+#endif
+#ifdef GPG_USE_ECDSA
+    case PUBKEY_ALGO_ECDSA:     ga = GCRY_PK_ECC;   break;
+#endif
+#ifdef GPG_USE_EDDSA
     case PUBKEY_ALGO_EDDSA:     ga = GCRY_PK_ECC;   break;
+#endif
 
     case PUBKEY_ALGO_ELGAMAL:
       /* Dont't allow type 20 keys unless in rfc2440 mode.  */
@@ -587,32 +604,38 @@ map_md_openpgp_to_gcry (digest_algo_t algo)
 {
   switch (algo)
     {
+#ifdef GPG_USE_MD5
     case DIGEST_ALGO_MD5:    return GCRY_MD_MD5;
+#endif
     case DIGEST_ALGO_SHA1:   return GCRY_MD_SHA1;
+#ifdef GPG_USE_RMD160
     case DIGEST_ALGO_RMD160: return GCRY_MD_RMD160;
+#endif
+#ifdef GPG_USE_SHA224
     case DIGEST_ALGO_SHA224: return GCRY_MD_SHA224;
+#endif
+#ifdef GPG_USE_SHA256
     case DIGEST_ALGO_SHA256: return GCRY_MD_SHA256;
+#endif
+#ifdef GPG_USE_SHA384
     case DIGEST_ALGO_SHA384: return GCRY_MD_SHA384;
+#endif
+#ifdef GPG_USE_512
     case DIGEST_ALGO_SHA512: return GCRY_MD_SHA512;
+#endif
     }
   return 0;
 }
 
 
 /* Return 0 if ALGO is suitable and implemented OpenPGP hash
-   algorithm.  Note: To only test for a valid OpenPGP hash algorithm,
-   it is better to use map_md_openpgp_to_gcry. */
+   algorithm.  */
 int
 openpgp_md_test_algo (digest_algo_t algo)
 {
   enum gcry_md_algos ga;
 
   ga = map_md_openpgp_to_gcry (algo);
-  switch (algo)
-    {
-    default:
-      break;
-    }
   if (!ga)
     return gpg_error (GPG_ERR_DIGEST_ALGO);