X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/b04a7659918367dcc8570e1c7b4246a97e88288d..ea932d59b3071ce00f9e510aad014ad64a3dc48c:/bbs-gen.c

diff --git a/bbs-gen.c b/bbs-gen.c
index 8780274..c668b21 100644
--- a/bbs-gen.c
+++ b/bbs-gen.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: bbs-gen.c,v 1.2 1999/12/22 15:52:28 mdw Exp $
+ * $Id: bbs-gen.c,v 1.6 2004/04/08 01:36:15 mdw Exp $
  *
  * Generate Blum integers
  *
  * (c) 1999 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,29 +15,18 @@
  * it under the terms of the GNU Library General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or (at your option) any later version.
- * 
+ *
  * Catacomb is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Library General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU Library General Public
  * License along with Catacomb; if not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: bbs-gen.c,v $
- * Revision 1.2  1999/12/22 15:52:28  mdw
- * Reworking for new prime-search system.
- *
- * Revision 1.1  1999/12/10 23:14:59  mdw
- * Blum-Blum-Shub generator, and Blum-Goldwasser encryption.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <stdio.h>
@@ -48,108 +37,89 @@
 #include "mp.h"
 #include "mprand.h"
 #include "pgen.h"
-
-/*----- Data structures ---------------------------------------------------*/
-
-typedef struct gcdctx {
-  mp *q;
-  mp *r;
-  pfilt p;
-} gcdctx;
-
-/*----- Custom stepper ----------------------------------------------------*/
-
-static int gcdstep(int rq, pgen_event *ev, void *p)
-{
-  gcdctx *g = p;
-  int rc = PGEN_ABORT;
-  mp *z = MP_NEW;
-
-  switch (rq) {
-    case PGEN_BEGIN: {
-      mp *p = ev->m = mp_split(ev->m);
-      p->v[0] |= 3;
-      g->q = mp_lsr(MP_NEW, p, 1);
-      rc = pfilt_create(&g->p, p);
-    } break;
-    case PGEN_TRY:
-      g->q = mp_add(g->q, g->q, MP_FOUR);
-      rc = pfilt_step(&g->p, 4);
-      break;
-    case PGEN_DONE:
-      pfilt_destroy(&g->p);
-      mp_drop(g->q);
-      return (PGEN_DONE);
-  }
-  for (;;) {
-    if (rc != PGEN_FAIL) {
-      mp_gcd(&z, 0, 0, g->r, g->q);
-      if (MP_CMP(z, !=, MP_ONE))
-	rc = PGEN_FAIL;
-    }
-    if (rc != PGEN_FAIL)
-      break;
-    g->q = mp_add(g->q, g->q, MP_FOUR);
-    rc = pfilt_step(&g->p, 4);
-  }
-
-  mp_drop(z);
-  mp_drop(ev->m);
-  ev->m = MP_COPY(g->p.m);
-  return (rc);
-}
+#include "strongprime.h"
 
 /*----- Main code ---------------------------------------------------------*/
 
 /* --- @bbs_gen@ --- *
  *
- * Arguments:	@bbs_param *bp@ = pointer to parameter block
- *		@mp *p, *q@ = initial numbers to search from
- *		@size_t n@ = number of attempts to make
+ * Arguments:	@bbs_priv *bp@ = pointer to parameter block
+ *		@unsigned nbits@ = number of bits in the modulus
+ *		@grand *r@ = pointer to random number source
+ *		@unsigned n@ = number of attempts to make
  *		@pgen_proc *event@ = event handler function
  *		@void *ectx@ = argument for event handler
  *
  * Returns:	If it worked OK, @PGEN_DONE@, otherwise @PGEN_ABORT@.
  *
  * Use:		Finds two prime numbers %$p'$% and %$q'$% such that both are
- *		congruent to %$3 \bmod 4$%, and  $(p - 1)/2$% and
+ *		congruent to %$3 \bmod 4$%, and	 $(p - 1)/2$% and
  *		%$(q - 1)/2$% have no common factors.  The product %$n = pq$%
  *		is eminently suitable for use as a modulus in a Blum-Blum-
  *		Shub pseudorandom bit generator.
  */
 
-int bbs_gen(bbs_param *bp, mp *p, mp *q, size_t n,
+int bbs_gen(bbs_priv *bp, unsigned nbits, grand *r, unsigned n,
 	    pgen_proc *event, void *ectx)
 {
-  rabin r;
-  pgen_safestepctx c;
-  gcdctx g;
+  rabin rb;
+  pfilt jp;
+  pgen_jumpctx j;
+  pgen_gcdstepctx g;
+  unsigned nb = nbits/2;
+  mp *x = MP_NEW;
 
   /* --- Generate @p@ --- */
 
-  if ((bp->p = pgen("p", MP_NEW, p, event, ectx, n, pgen_safestep, &c,
-		    rabin_iters(mp_bits(p)), pgen_test, &r)) == 0)
-    goto fail_p;
+again:
+  if ((x = strongprime_setup("p", x, &jp, nb, r, n, event, ectx)) == 0)
+    goto fail_x;
+  j.j = &jp;
+  bp->p = pgen("p", MP_NEW, x, event, ectx, n, pgen_jump, &j,
+	       rabin_iters(nb), pgen_test, &rb);
+  pfilt_destroy(&jp);
+  if (!bp->p) {
+    if (n)
+      goto fail_p;
+    goto again;
+  }
 
   /* --- Generate @q@ --- */
 
-  g.r = mp_lsr(MP_NEW, bp->p, 1);
-  if ((bp->q = pgen("q", MP_NEW, q, event, ectx, n, gcdstep, &g,
-		    rabin_iters(mp_bits(q)), pgen_test, &r)) == 0)
+  nb = nbits - nb;
+  if ((x = strongprime_setup("q", x, &g.jp, nb, r, n, event, ectx)) == 0)
     goto fail_q;
+  if ((x->v[0] & 3) != 3)
+    x = mp_add(x, x, g.jp.m);
+  pfilt_muladd(&g.jp, &g.jp, 2, 0);
+  g.r = mp_lsr(MP_NEW, bp->p, 1);
+  g.g = MP_NEW;
+  g.max = MP_ONE;
+  bp->q = pgen("q", MP_NEW, x, event, ectx, n, pgen_gcdstep, &g,
+	       rabin_iters(nb), pgen_test, &rb);
+  pfilt_destroy(&g.jp);
+  mp_drop(g.r);
+  mp_drop(g.g);
+  if (!bp->q) {
+    if (n)
+      goto fail_q;
+    mp_drop(bp->p);
+    goto again;
+  }
 
   /* --- Compute @n@ --- */
 
   bp->n = mp_mul(MP_NEW, bp->p, bp->q);
-  mp_drop(g.r);
+  mp_drop(x);
   return (PGEN_DONE);
 
   /* --- Tidy up if things went wrong --- */
 
 fail_q:
-  mp_drop(g.r);
   mp_drop(bp->p);
 fail_p:
+  mp_drop(x);
+fail_x:
   return (PGEN_ABORT);
 }