/* -*-c-*-
*
- * $Id: bbs-jump.c,v 1.5 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
*
* Jumping around a BBS sequence
*
/* --- @jump@ --- *
*
* Arguments: @bbs *b@ = pointer to BBS generator context
- * @bbs_priv *bp@ = pointer to BBS modulus factors
- * @unsigned long n@ = number of steps to move
+ * @const bbs_priv *bp@ = pointer to BBS modulus factors
+ * @mp *n@ = number of steps to move
* @mp *px@ = exponent mod @p@ for a one-step jump
* @mp *qx@ = exponent mod @q@ for a one-step jump
*
* %$p \equiv 3 \pmod 4$%.)
*/
-static void jump(bbs *b, bbs_priv *bp, unsigned long n,
+static void jump(bbs *b, const bbs_priv *bp, mp *n,
mp *px, mp *qx)
{
mp *ep, *eq;
{
mpbarrett mb;
mp *m;
- mp *e;
- e = mp_fromulong(MP_NEW, n);
m = mp_sub(MP_NEW, bp->p, MP_ONE);
mpbarrett_create(&mb, m);
- ep = mpbarrett_exp(&mb, MP_NEW, px, e);
+ ep = mpbarrett_exp(&mb, MP_NEW, px, n);
mpbarrett_destroy(&mb);
if (qx == px)
eq = MP_COPY(ep);
else {
m = mp_sub(m, bp->q, MP_ONE);
mpbarrett_create(&mb, m);
- eq = mpbarrett_exp(&mb, MP_NEW, qx, e);
+ eq = mpbarrett_exp(&mb, MP_NEW, qx, n);
mpbarrett_destroy(&mb);
}
mp_drop(m);
- mp_drop(e);
}
/* --- Now calculate the residues of @x@ --- */
b->b = b->k;
}
-/* --- @bbs_ff@ --- *
+/* --- @bbs_{ff,rew}{,n}@ --- *
*
* Arguments: @bbs *b@ = pointer to a BBS generator state
- * @bbs_priv *bp@ = pointer to BBS modulus factors
- * @unsigned long n@ = number of steps to make
+ * @const bbs_priv *bp@ = pointer to BBS modulus factors
+ * @mp *n@, @unsigned long n@ = number of steps to make
*
* Returns: ---
*
- * Use: `Fast-forwards' a Blum-Blum-Shub generator by @n@ steps.
- * Requires the factorization of the Blum modulus to do this
- * efficiently.
+ * Use: `Fast-forwards' or rewinds a Blum-Blum-Shub generator by @n@
+ * steps. The @...n@ versions take an @unsigned long@ argument;
+ * the non-@...n@ versions a multiprecision integer. If @n@ is
+ * negative then the generator is stepped in the reverse
+ * direction.
*/
-void bbs_ff(bbs *b, bbs_priv *bp, unsigned long n)
-{
- jump(b, bp, n, MP_TWO, MP_TWO);
-}
-
-/* --- @bbs_rew@ --- *
- *
- * Arguments: @bbs *b@ = pointer to a BBS generator state
- * @bbs_priv *bp@ = pointer to BBS modulus factors
- * @unsigned long n@ = number of steps to make
- *
- * Returns: ---
- *
- * Use: `Rewinds' a Blum-Blum-Shub generator by @n@ steps.
- * Requires the factorization of the Blum modulus to do this
- * at all.
- */
+static void ff(bbs *b, const bbs_priv *bp, mp *n)
+ { jump(b, bp, n, MP_TWO, MP_TWO); }
-void bbs_rew(bbs *b, bbs_priv *bp, unsigned long n)
+static void rew(bbs *b, const bbs_priv *bp, mp *n)
{
mp *px = mp_lsr(MP_NEW, bp->p, 2);
mp *qx = mp_lsr(MP_NEW, bp->q, 2);
mp_drop(qx);
}
+void bbs_ff(bbs *b, const bbs_priv *bp, mp *n)
+{
+ if (!MP_NEGP(n))
+ ff(b, bp, n);
+ else {
+ n = mp_neg(MP_NEW, n);
+ rew(b, bp, n);
+ mp_drop(n);
+ }
+}
+
+void bbs_ffn(bbs *b, const bbs_priv *bp, unsigned long n)
+ { mp *nn = mp_fromulong(MP_NEW, n); ff(b, bp, nn); mp_drop(nn); }
+
+void bbs_rew(bbs *b, const bbs_priv *bp, mp *n)
+{
+ if (!MP_NEGP(n))
+ rew(b, bp, n);
+ else {
+ n = mp_neg(MP_NEW, n);
+ ff(b, bp, n);
+ mp_drop(n);
+ }
+}
+
+void bbs_rewn(bbs *b, const bbs_priv *bp, unsigned long n)
+ { mp *nn = mp_fromulong(MP_NEW, n); bbs_rew(b, bp, nn); mp_drop(nn); }
+
/*----- Test rig ----------------------------------------------------------*/
#ifdef TEST_RIG
q = bbs_bits(&b, 32);
bbs_wrap(&b);
- bbs_rew(&b, &bp, n + (32 + b.k - 1) / b.k);
+ bbs_rewn(&b, &bp, n + (32 + b.k - 1) / b.k);
r = bbs_bits(&b, 32);
if (r != p) {
}
bbs_seed(&b, x);
- bbs_ff(&b, &bp, n);
+ bbs_ffn(&b, &bp, n);
r = bbs_bits(&b, 32);
if (q != r) {
/* -*-c-*-
*
- * $Id: bbs-rand.c,v 1.5 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
*
* Blum-Blum-Shub secure random number generator
*
case GRAND_SEEDMP:
case GRAND_SEEDRAND:
case BBS_SET:
+ case BBS_STEP:
+ case BBS_STEPSZ:
+ case BBS_BITS:
+ case BBS_WRAP:
+ case BBS_FF:
+ case BBS_FFN:
+ case BBS_REW:
+ case BBS_REWN:
+ case BBS_MOD:
+ case BBS_STATE:
rc = 1;
break;
default:
case BBS_SET:
bbs_set(&g->b, va_arg(ap, mp *));
break;
+ case BBS_STEP:
+ bbs_step(&g->b);
+ break;
+ case BBS_STEPSZ:
+ rc = g->b.k;
+ break;
+ case BBS_BITS: {
+ unsigned nb = va_arg(ap, unsigned);
+ uint32 *w = va_arg(ap, uint32 *);
+ *w = bbs_bits(&g->b, nb);
+ } break;
+ case BBS_WRAP:
+ bbs_wrap(&g->b);
+ break;
+ case BBS_FF: {
+ const bbs_priv *bp = va_arg(ap, const bbs_priv *);
+ mp *n = va_arg(ap, mp *);
+ bbs_ff(&g->b, bp, n);
+ } break;
+ case BBS_FFN: {
+ const bbs_priv *bp = va_arg(ap, const bbs_priv *);
+ unsigned long n = va_arg(ap, unsigned long);
+ bbs_ffn(&g->b, bp, n);
+ } break;
+ case BBS_REW: {
+ const bbs_priv *bp = va_arg(ap, const bbs_priv *);
+ mp *n = va_arg(ap, mp *);
+ bbs_rew(&g->b, bp, n);
+ } break;
+ case BBS_REWN: {
+ const bbs_priv *bp = va_arg(ap, const bbs_priv *);
+ unsigned long n = va_arg(ap, unsigned long);
+ bbs_rewn(&g->b, bp, n);
+ } break;
+ case BBS_MOD: {
+ mp **n = va_arg(ap, mp **);
+ if (*n) MP_DROP(*n);
+ *n = MP_COPY(g->b.mb.m);
+ } break;
+ case BBS_STATE: {
+ mp **n = va_arg(ap, mp **);
+ if (*n) MP_DROP(*n);
+ *n = MP_COPY(g->b.x);
+ } break;
default:
GRAND_BADOP;
break;
/* -*-c-*-
*
- * $Id: bbs.h,v 1.7 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
*
* The Blum-Blum-Shub random bit generator
*
/*----- Large forwards and backwards jumps --------------------------------*/
-/* --- @bbs_ff@ --- *
+/* --- @bbs_{ff,rew}{,n}@ --- *
*
* Arguments: @bbs *b@ = pointer to a BBS generator state
- * @bbs_priv *bp@ = pointer to BBS modulus factors
- * @unsigned long n@ = number of steps to make
+ * @const bbs_priv *bp@ = pointer to BBS modulus factors
+ * @mp *n@, @unsigned long n@ = number of steps to make
*
* Returns: ---
*
- * Use: `Fast-forwards' a Blum-Blum-Shub generator by @n@ steps.
- * Requires the factorization of the Blum modulus to do this
- * efficiently.
+ * Use: `Fast-forwards' or rewinds a Blum-Blum-Shub generator by @n@
+ * steps. The @...n@ versions take an @unsigned long@ argument;
+ * the non-@...n@ versions a multiprecision integer. If @n@ is
+ * negative then the generator is stepped in the reverse
+ * direction.
*/
-extern void bbs_ff(bbs */*b*/, bbs_priv */*bp*/, unsigned long /*n*/);
-
-/* --- @bbs_rew@ --- *
- *
- * Arguments: @bbs *b@ = pointer to a BBS generator state
- * @bbs_priv *bp@ = pointer to BBS modulus factors
- * @unsigned long n@ = number of steps to make
- *
- * Returns: ---
- *
- * Use: `Rewinds' a Blum-Blum-Shub generator by @n@ steps.
- * Requires the factorization of the Blum modulus to do this
- * at all.
- */
-
-extern void bbs_rew(bbs */*b*/, bbs_priv */*bp*/, unsigned long /*n*/);
+extern void bbs_ff(bbs */*b*/, const bbs_priv */*bp*/, mp */*n*/);
+extern void bbs_ffn(bbs */*b*/, const bbs_priv */*bp*/, unsigned long /*n*/);
+extern void bbs_rew(bbs */*b*/, const bbs_priv */*bp*/, mp */*n*/);
+extern void bbs_rewn(bbs */*b*/, const bbs_priv */*bp*/, unsigned long /*n*/);
/*----- Parameter generation ----------------------------------------------*/
/* --- Blum-Blum-Shub-specific misc op codes --- */
enum {
- BBS_SET = GRAND_SPECIFIC('B') /* @mp *x@ */
+ BBS_SET = GRAND_SPECIFIC('B'), /* @mp *x@ */
+ BBS_STEP, /* @void@ */
+ BBS_STEPSZ, /* @void@ */
+ BBS_BITS, /* @unsigned bits, uint32 *w@ */
+ BBS_WRAP, /* @void@ */
+ BBS_FF, /* @bbs_priv *p, mp *n@ */
+ BBS_FFN, /* @bbs_priv *p, unsigned long n@ */
+ BBS_REW, /* @bbs_priv *p, mp *n@ */
+ BBS_REWN, /* @bbs_priv *p, unsigned long n@ */
+ BBS_MOD, /* @mp **n@ */
+ BBS_STATE /* @mp **x@ */
};
/*----- That's all, folks -------------------------------------------------*/