diff --git a/rhizome_crypto.c b/rhizome_crypto.c
index b57297d2..b87b6343 100644
--- a/rhizome_crypto.c
+++ b/rhizome_crypto.c
@@ -24,14 +24,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <stdlib.h>
 #include <ctype.h>
 
-/* Work out the encrypt/decrypt key for the supplied manifest.
-   If the manifest is not encrypted, then return NULL.
-*/
-unsigned char *rhizome_bundle_shared_secret(rhizome_manifest *m)
-{
-  return NULL;
-}
-
 int rhizome_manifest_createid(rhizome_manifest *m)
 {
   m->haveSecret=NEW_BUNDLE_ID;