X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ab9fc001a865ff5c9e08e84298be9bcb9cc61e1b..3563e36580c7dad68cd6d3f7eb82eef570fc0c76:/mprand.c

diff --git a/mprand.c b/mprand.c
index bf8af69..46e603c 100644
--- a/mprand.c
+++ b/mprand.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mprand.c,v 1.2 1999/12/22 15:55:33 mdw Exp $
+ * $Id: mprand.c,v 1.4 2001/05/07 17:31:19 mdw Exp $
  *
  * Generate a random multiprecision integer
  *
@@ -30,6 +30,16 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mprand.c,v $
+ * Revision 1.4  2001/05/07 17:31:19  mdw
+ * Fix off-by one bug in mprand_range.  Probably security critical: the old
+ * code generated numbers between zero and the highest power of 2 less than
+ * the given range.
+ *
+ * Revision 1.3  2000/06/17 11:45:09  mdw
+ * Major memory management overhaul.  Added arena support.  Use the secure
+ * arena for secret integers.  Replace and improve the MP management macros
+ * (e.g., replace MP_MODIFY by MP_DEST).
+ *
  * Revision 1.2  1999/12/22 15:55:33  mdw
  * Modify `mprand' slightly.  Add `mprand_range'.
  *
@@ -67,7 +77,8 @@
 mp *mprand(mp *d, unsigned b, grand *r, mpw or)
 {
   size_t sz = (b + 7) >> 3;
-  octet *v = xmalloc(sz);
+  arena *a = (d && (d->f & MP_BURN)) ? arena_secure : arena_global;
+  octet *v = x_alloc(a, sz);
   unsigned m;
 
   /* --- Fill buffer with random data --- */
@@ -87,7 +98,8 @@ mp *mprand(mp *d, unsigned b, grand *r, mpw or)
 
   d = mp_loadb(d, v, sz);
   d->v[0] |= or;
-  free(v);
+  memset(v, 0, sz);
+  x_free(a, v);
   return (d);
 }
 
@@ -109,7 +121,8 @@ mp *mprand_range(mp *d, mp *l, grand *r, mpw or)
 {
   size_t b = mp_bits(l);
   size_t sz = (b + 7) >> 3;
-  octet *v = xmalloc(sz);
+  arena *a = (d && (d->f & MP_BURN)) ? arena_secure : arena_global;
+  octet *v = x_alloc(a, sz);
   unsigned m;
 
   /* --- The algorithm --- *
@@ -129,7 +142,7 @@ mp *mprand_range(mp *d, mp *l, grand *r, mpw or)
    * As usual, the number of iterations expected is two.
    */
 
-  b = (b - 1) & 7;
+  b = ((b - 1) & 7) + 1;
   m = (1 << b) - 1;
   do {
     r->ops->fill(r, v, sz);
@@ -140,7 +153,8 @@ mp *mprand_range(mp *d, mp *l, grand *r, mpw or)
 
   /* --- Done --- */
 
-  free(v);
+  memset(v, 0, sz);
+  x_free(a, v);
   return (d);
 }