diff -r 000000000000 -r 6474c204b198 security/nss/lib/freebl/mpi/utils/identest.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/security/nss/lib/freebl/mpi/utils/identest.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi.h"
+#include "mpprime.h"
+#include <sys/types.h>
+#include <time.h>
+
+#define MAX_PREC (4096 / MP_DIGIT_BIT)
+
+mp_err identity_test(void)
+{
+  mp_size       preca, precb;
+  mp_err        res;
+  mp_int        a, b;
+  mp_int        t1, t2, t3, t4, t5;
+
+  preca = (rand() % MAX_PREC) + 1;
+  precb = (rand() % MAX_PREC) + 1;
+
+  MP_DIGITS(&a) = 0;
+  MP_DIGITS(&b) = 0;
+  MP_DIGITS(&t1) = 0;
+  MP_DIGITS(&t2) = 0;
+  MP_DIGITS(&t3) = 0;
+  MP_DIGITS(&t4) = 0;
+  MP_DIGITS(&t5) = 0;
+
+  MP_CHECKOK( mp_init(&a)  );
+  MP_CHECKOK( mp_init(&b)  );
+  MP_CHECKOK( mp_init(&t1) );
+  MP_CHECKOK( mp_init(&t2) );
+  MP_CHECKOK( mp_init(&t3) );
+  MP_CHECKOK( mp_init(&t4) );
+  MP_CHECKOK( mp_init(&t5) );
+
+  MP_CHECKOK( mpp_random_size(&a, preca) );
+  MP_CHECKOK( mpp_random_size(&b, precb) );
+
+  if (mp_cmp(&a, &b) < 0)
+    mp_exch(&a, &b);
+
+  MP_CHECKOK( mp_mod(&a, &b, &t1) );       /* t1 = a%b */
+  MP_CHECKOK( mp_div(&a, &b, &t2, NULL) ); /* t2 = a/b */
+  MP_CHECKOK( mp_mul(&b, &t2, &t3) );      /* t3 = (a/b)*b */
+  MP_CHECKOK( mp_add(&t1, &t3, &t4) );     /* t4 = a%b + (a/b)*b */
+  MP_CHECKOK( mp_sub(&t4, &a, &t5) );      /* t5 = a%b + (a/b)*b - a */
+  if (mp_cmp_z(&t5) != 0) {
+    res = MP_UNDEF;
+    goto CLEANUP;
+  }
+
+CLEANUP:
+  mp_clear(&t5);
+  mp_clear(&t4);
+  mp_clear(&t3);
+  mp_clear(&t2);
+  mp_clear(&t1);
+  mp_clear(&b);
+  mp_clear(&a);
+  return res;
+}
+
+int
+main(void)
+{
+  unsigned int  seed = (unsigned int)time(NULL);
+  unsigned long count = 0;
+  mp_err        res;
+
+  srand(seed);
+
+  while (MP_OKAY == (res = identity_test())) {
+     if ((++count % 100) == 0)
+       fputc('.', stderr);
+  }
+
+  fprintf(stderr, "\ntest failed, err %d\n", res);
+  return res;
+}