Speed up "w = iv(s) mod q" by eliminating the unnecessary {u,v,t}2

computation.

CVS patchset: 5340
CVS date: 2002/02/28 22:08:55

diff --git a/beecrypt/mp32barrett.c b/beecrypt/mp32barrett.c
index 508c1771dd459c6f93ec259722697f6b3c57b62e..b39ed4ece63819f5b5a775a3b620a82ad5ae77c9 100644 (file)
--- a/beecrypt/mp32barrett.c
+++ b/beecrypt/mp32barrett.c
@@ -909,6 +909,8 @@ int mp32binv_w(const mp32barrett* b, uint32 xsize, const uint32* xdata, uint32*
 
 static int _debug = 0;
 
+#undef FULL_BINARY_EXTENDED_GCD
+
 /**
  *  Computes the inverse (modulo b) of x, and returns 1 if x was invertible.
  */
@@ -916,17 +918,20 @@ int mp32binv_w(const mp32barrett* b, uint32 xsize, const uint32* xdata, uint32*
 {
        uint32  ysize = b->size+1;
        int k;
-       uint32* u1 = wksp;
-       uint32* u2 = u1+ysize;
-       uint32* u3 = u2+ysize;
-       uint32* v1 = u3+ysize;
-       uint32* v2 = v1+ysize;
-       uint32* v3 = v2+ysize;
-       uint32* t1 = v3+ysize;
-       uint32* t2 = t1+ysize;
-       uint32* t3 = t2+ysize;
-       uint32* u  = t3+ysize;
+       uint32* u  = wksp;
        uint32* v  =  u+ysize;
+       uint32* u1 =  v+ysize;
+       uint32* v1 = u1+ysize;
+       uint32* t1 = v1+ysize;
+       uint32* u3 = t1+ysize;
+       uint32* v3 = u3+ysize;
+       uint32* t3 = v3+ysize;
+
+#ifdef FULL_BINARY_EXTENDED_GCD
+       uint32* u2 = t3+ysize;
+       uint32* v2 = u2+ysize;
+       uint32* t2 = v2+ysize;
+#endif
 
        mp32setx(ysize, u, xsize, xdata);
        mp32setx(ysize, v, b->size, b->modl);
@@ -937,126 +942,139 @@ int mp32binv_w(const mp32barrett* b, uint32 xsize, const uint32* xdata, uint32*
                mp32divtwo(ysize, v);
        }
 
-if (_debug < 0)
-fprintf(stderr, "       u: "), mp32println(stderr, ysize, u);
-if (_debug < 0)
-fprintf(stderr, "       v: "), mp32println(stderr, ysize, v);
-
        /* Y2. Initialize. */
        mp32setw(ysize, u1, 1);
-if (_debug < 0)
-fprintf(stderr, "      u1: "), mp32println(stderr, ysize, u1);
-       mp32zero(ysize, u2);
-if (_debug < 0)
-fprintf(stderr, "      u2: "), mp32println(stderr, ysize, u2);
+       mp32setx(ysize, v1, ysize, v);
        mp32setx(ysize, u3, ysize, u);
-if (_debug < 0)
-fprintf(stderr, "      u3: "), mp32println(stderr, ysize, u3);
+       mp32setx(ysize, v3, ysize, v);
 
-       mp32setx(ysize, v1, ysize, v);
-if (_debug < 0)
-fprintf(stderr, "      v1: "), mp32println(stderr, ysize, v1);
+#ifdef FULL_BINARY_EXTENDED_GCD
+       mp32zero(ysize, u2);
        mp32setw(ysize, v2, 1);
        (void) mp32sub(ysize, v2, u);
-if (_debug < 0)
+#endif
+
+if (_debug < 0) {
+fprintf(stderr, "       u: "), mp32println(stderr, ysize, u);
+fprintf(stderr, "       v: "), mp32println(stderr, ysize, v);
+fprintf(stderr, "      u1: "), mp32println(stderr, ysize, u1);
+#ifdef FULL_BINARY_EXTENDED_GCD
+fprintf(stderr, "      u2: "), mp32println(stderr, ysize, u2);
+#endif
+fprintf(stderr, "      u3: "), mp32println(stderr, ysize, u3);
+fprintf(stderr, "      v1: "), mp32println(stderr, ysize, v1);
+#ifdef FULL_BINARY_EXTENDED_GCD
 fprintf(stderr, "      v2: "), mp32println(stderr, ysize, v2);
-       mp32setx(ysize, v3, ysize, v);
-if (_debug < 0)
+#endif
 fprintf(stderr, "      v3: "), mp32println(stderr, ysize, v3);
+}
 
        if (mp32odd(ysize, u)) {
                mp32zero(ysize, t1);
-if (_debug < 0)
-fprintf(stderr, "      t1: "), mp32println(stderr, ysize, t1);
+#ifdef FULL_BINARY_EXTENDED_GCD
                mp32zero(ysize, t2);
                mp32subw(ysize, t2, 1);
-if (_debug < 0)
-fprintf(stderr, "      t2: "), mp32println(stderr, ysize, t2);
+#endif
                mp32zero(ysize, t3);
                mp32sub(ysize, t3, v);
-if (_debug < 0)
-fprintf(stderr, "      t3: "), mp32println(stderr, ysize, t3);
                goto Y4;
        } else {
                mp32setw(ysize, t1, 1);
-if (_debug < 0)
-fprintf(stderr, "      t1: "), mp32println(stderr, ysize, t1);
+#ifdef FULL_BINARY_EXTENDED_GCD
                mp32zero(ysize, t2);
-if (_debug < 0)
-fprintf(stderr, "      t2: "), mp32println(stderr, ysize, t2);
+#endif
                mp32setx(ysize, t3, ysize, u);
-if (_debug < 0)
-fprintf(stderr, "      t3: "), mp32println(stderr, ysize, t3);
        }
 
        do {
            do {
-               if (mp32odd(ysize, t1) || mp32odd(ysize, t2)) {
+#ifdef FULL_BINARY_EXTENDED_GCD
+               if (mp32odd(ysize, t1) ||  mp32odd(ysize, t2)) {
                        mp32add(ysize, t1, v);
                        mp32sub(ysize, t2, u);
                }
+#else
+               /* XXX this assumes v is odd, true for DSA inversion. */
+               if (mp32odd(ysize, t1))
+                       mp32add(ysize, t1, v);
+#endif
+
                mp32sdivtwo(ysize, t1);
+#ifdef FULL_BINARY_EXTENDED_GCD
                mp32sdivtwo(ysize, t2);
+#endif
                mp32sdivtwo(ysize, t3);
 Y4:
-if (_debug < 0)
-fprintf(stderr, "   Y4 t3: "), mp32println(stderr, ysize, t3);
+if (_debug < 0) {
+fprintf(stderr, "-->Y4 t3: "), mp32println(stderr, ysize, t3);
+#ifdef FULL_BINARY_EXTENDED_GCD
+fprintf(stderr, "      t2: "), mp32println(stderr, ysize, t2);
+#endif
+fprintf(stderr, "      t1: "), mp32println(stderr, ysize, t1);
+}
            } while (mp32even(ysize, t3));
 
            /* Y5. Reset max(u3,v3). */
            if (!(*t3 & 0x80000000)) {
-if (_debug < 0)
-fprintf(stderr, "--> Y5 (t3 > 0)\n");
                mp32setx(ysize, u1, ysize, t1);
-if (_debug < 0)
-fprintf(stderr, "      u1: "), mp32println(stderr, ysize, u1);
+#ifdef FULL_BINARY_EXTENDED_GCD
                mp32setx(ysize, u2, ysize, t2);
-if (_debug < 0)
-fprintf(stderr, "      u2: "), mp32println(stderr, ysize, u2);
+#endif
                mp32setx(ysize, u3, ysize, t3);
-if (_debug < 0)
+if (_debug < 0) {
+fprintf(stderr, "-->Y5 u1: "), mp32println(stderr, ysize, u1);
+#ifdef FULL_BINARY_EXTENDED_GCD
+fprintf(stderr, "      u2: "), mp32println(stderr, ysize, u2);
+#endif
 fprintf(stderr, "      u3: "), mp32println(stderr, ysize, u3);
+}
            } else {
-if (_debug < 0)
-fprintf(stderr, "--> Y5 (t3 <= 0)\n");
                mp32setx(ysize, v1, ysize, v);
                mp32sub(ysize, v1, t1);
-if (_debug < 0)
-fprintf(stderr, "      v1: "), mp32println(stderr, ysize, v1);
+#ifdef FULL_BINARY_EXTENDED_GCD
                mp32setx(ysize, v2, ysize, u);
                mp32neg(ysize, v2);
                mp32sub(ysize, v2, t2);
-if (_debug < 0)
-fprintf(stderr, "      v2: "), mp32println(stderr, ysize, v2);
+#endif
                mp32zero(ysize, v3);
                mp32sub(ysize, v3, t3);
-if (_debug < 0)
+if (_debug < 0) {
+fprintf(stderr, "-->Y5 v1: "), mp32println(stderr, ysize, v1);
+#ifdef FULL_BINARY_EXTENDED_GCD
+fprintf(stderr, "      v2: "), mp32println(stderr, ysize, v2);
+#endif
 fprintf(stderr, "      v3: "), mp32println(stderr, ysize, v3);
+}
            }
 
            /* Y6. Subtract. */
            mp32setx(ysize, t1, ysize, u1);
            mp32sub(ysize, t1, v1);
+#ifdef FULL_BINARY_EXTENDED_GCD
            mp32setx(ysize, t2, ysize, u2);
            mp32sub(ysize, t2, v2);
+#endif
            mp32setx(ysize, t3, ysize, u3);
            mp32sub(ysize, t3, v3);
 
            if (*t1 & 0x80000000) {
                mp32add(ysize, t1, v);
+#ifdef FULL_BINARY_EXTENDED_GCD
                mp32sub(ysize, t2, u);
+#endif
            }
 
-if (_debug < 0)
+if (_debug < 0) {
 fprintf(stderr, "-->Y6 t1: "), mp32println(stderr, ysize, t1);
-if (_debug < 0)
+#ifdef FULL_BINARY_EXTENDED_GCD
 fprintf(stderr, "      t2: "), mp32println(stderr, ysize, t2);
-if (_debug < 0)
+#endif
 fprintf(stderr, "      t3: "), mp32println(stderr, ysize, t3);
+}
 
        } while (mp32nz(ysize, t3));
 
-       if (!(mp32isone(ysize, u3) && mp32isone(ysize, v3)))
+       if (!mp32isone(ysize, u3) || !mp32isone(ysize, v3))
                return 0;
 
        if (result) {
@@ -1068,13 +1086,19 @@ fprintf(stderr, "      t3: "), mp32println(stderr, ysize, t3);
 if (_debug) {
 fprintf(stderr, "=== EXIT: "), mp32println(stderr, b->size, result);
 fprintf(stderr, "      u1: "), mp32println(stderr, ysize, u1);
+#ifdef FULL_BINARY_EXTENDED_GCD
 fprintf(stderr, "      u2: "), mp32println(stderr, ysize, u2);
+#endif
 fprintf(stderr, "      u3: "), mp32println(stderr, ysize, u3);
 fprintf(stderr, "      v1: "), mp32println(stderr, ysize, v1);
+#ifdef FULL_BINARY_EXTENDED_GCD
 fprintf(stderr, "      v2: "), mp32println(stderr, ysize, v2);
+#endif
 fprintf(stderr, "      v3: "), mp32println(stderr, ysize, v3);
 fprintf(stderr, "      t1: "), mp32println(stderr, ysize, t1);
+#ifdef FULL_BINARY_EXTENDED_GCD
 fprintf(stderr, "      t2: "), mp32println(stderr, ysize, t2);
+#endif
 fprintf(stderr, "      t3: "), mp32println(stderr, ysize, t3);
 }