Index: mpi-1.8.6/mpi.c
===================================================================
--- mpi-1.8.6.orig/mpi.c	2011-12-09 14:10:41.000000000 -0800
+++ mpi-1.8.6/mpi.c	2011-12-09 14:26:02.000000000 -0800
@@ -1960,6 +1960,30 @@
 
 /* }}} */
 
+unsigned long mp_hash(mp_int *a)
+{
+  unsigned long hash = 0;
+  int ix;
+  for (ix = 0; ix < USED(a); ix++) {
+    mp_digit d = DIGIT(a, ix);
+#if SIZEOF_LONG < MP_DIGIT_SIZE
+    int j;
+    for (j = 0; j < MP_DIGIT_SIZE / SIZEOF_LONG; j++) {
+	hash ^= d;
+	d >> (SIZEOF_LONG * CHAR_BIT);
+    }
+#elif SIZEOF_LONG == MP_DIGIT_SIZE
+    hash ^= d;
+#else
+    hash <<= MP_DIGIT_BITS;
+    hash ^= d;
+#endif
+  }
+  if (SIGN(a) == MP_NEG)
+    hash = (hash << 16 | hash >> (SIZEOF_LONG * CHAR_BIT - 16));
+  return hash;
+}
+
 /*------------------------------------------------------------------------*/
 /* {{{ Number theoretic functions */
 
Index: mpi-1.8.6/mpi.h
===================================================================
--- mpi-1.8.6.orig/mpi.h	2011-12-09 14:10:41.000000000 -0800
+++ mpi-1.8.6/mpi.h	2011-12-09 14:10:41.000000000 -0800
@@ -165,6 +165,8 @@
 int    mp_isodd(mp_int *a);
 int    mp_iseven(mp_int *a);
 
+unsigned long mp_hash(mp_int *a);
+
 /*------------------------------------------------------------------------*/
 /* Number theoretic                                                       */