diff --git a/src/compiler.c b/src/compiler.c
index 8a9d093..79cb51c 100644
--- a/src/compiler.c
+++ b/src/compiler.c
@@ -836,6 +836,49 @@ commEvent (int event, Tac tc)
     }
 }
 
+//! Create hash functions
+/**
+ * Assumption: hfuncs list in same order as tac.
+ *
+ * Note: Destroys tc contents, so please don't reuse afterwards.
+ */
+int
+hashfunctions (Tac tcstart)
+{
+  Termlist hfuncs;
+  Termlist hinvs;
+  Tac tc;
+
+  // As long as tc is intact.
+  levelDeclareConst (tcstart);
+  hfuncs = tacTermlist (tcstart->t1.tac);
+  if (level < 2)
+    knowledgeAddTermlist (sys->know, hfuncs);
+
+  for (tc = tcstart->t1.tac; tc != NULL; tc = tc->next)
+    {
+      tc->t1.sym = symbolNextFree (symbolSysConst ("_unhash-"));
+    }
+  levelDeclareConst (tcstart);
+  hinvs = tacTermlist (tcstart->t1.tac);
+
+  while (hfuncs != NULL)
+    {
+      if (hinvs == NULL)
+	{
+	  error
+	    ("Bug in hashfunction generation code. Please contact the authors.\n");
+	}
+      knowledgeAddInverse (sys->know, hfuncs->term, hinvs->term);
+      hfuncs->term->stype = termlistAdd (NULL, TERM_Function);
+      hinvs->term->stype = termlistAdd (NULL, TERM_Function);
+      hfuncs = hfuncs->next;
+      hinvs = hinvs->next;
+    }
+  return true;
+}
+
+
 int
 normalDeclaration (Tac tc)
 {
@@ -885,6 +928,9 @@ normalDeclaration (Tac tc)
       knowledgeAddInverse (sys->know, tacTerm (tc->t1.tac),
 			   tacTerm (tc->t2.tac));
       break;
+    case TAC_HASHFUNCTION:
+      hashfunctions (tc);
+      break;
     default:
       /* abort with false */
       return 0;
@@ -1295,6 +1341,10 @@ tacTerm (Tac tc)
     }
 }
 
+//! Extract termlist from tac
+/**
+ * Note: termlist in same order as tac. This is required for correct working of functions such as 'hashfunctions'.
+ */
 Termlist
 tacTermlist (Tac tc)
 {
diff --git a/src/parser.y b/src/parser.y
index c6469be..d8f51ab 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -257,6 +257,13 @@ declaration	: secretpref CONST basictermlist typeinfo1 ';'
 		  	t->t1.tac= $2;
 			$$ = t;
 		  }
+		| HASHFUNCTION basictermlist ';'
+		  {	Tac t = tacCreate(TAC_HASHFUNCTION);
+		  	t->t1.tac = $2;
+		  	t->t2.tac = tacCreate(TAC_UNDEF);
+			t->t3.tac = NULL;	// Not secret: public
+			$$ = t;
+		  }
 		;
 
 secretpref	: /* empty */
diff --git a/src/tac.c b/src/tac.c
index 59407b2..306ae56 100644
--- a/src/tac.c
+++ b/src/tac.c
@@ -330,6 +330,11 @@ tacPrint (Tac t)
       tacPrint (t->t2.tac);
       printf (");\n");
       break;
+    case TAC_HASHFUNCTION:
+      printf ("hashfunction ");
+      tacPrint (t->t1.tac);
+      printf (";\n");
+      break;
     case TAC_UNTRUSTED:
       printf ("untrusted ");
       tacPrint (t->t1.tac);
diff --git a/src/tac.h b/src/tac.h
index 6183d16..c2e8301 100644
--- a/src/tac.h
+++ b/src/tac.h
@@ -47,6 +47,7 @@ enum tactypes
   TAC_ROLEREF,
   TAC_SECRET,
   TAC_INVERSEKEYS,
+  TAC_HASHFUNCTION,
   TAC_UNTRUSTED,
   TAC_COMPROMISED,
   TAC_USERTYPE