X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fbn%2Fbn_mul.c;h=5a92f9a335c76b333bbc333930029da9a7bbcbcc;hp=83ff39abfef238633f20c0f016ec391b60ab65c2;hb=d870740cd75dd4f0cb66fb8c32653a7d47369706;hpb=651d0aff98d28e2db146afa1790e9e22f3ef22db

diff --git a/crypto/bn/bn_mul.c b/crypto/bn/bn_mul.c
index 83ff39abfe..5a92f9a335 100644
--- a/crypto/bn/bn_mul.c
+++ b/crypto/bn/bn_mul.c
@@ -56,67 +56,392 @@
  * [including the GNU Public Licence.]
  */
 
+#ifndef BN_DEBUG
+# undef NDEBUG /* avoid conflicting definitions */
+# define NDEBUG
+#endif
+
 #include <stdio.h>
+#include <assert.h>
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
+#if defined(OPENSSL_NO_ASM) || !defined(OPENSSL_BN_ASM_PART_WORDS)
+/* Here follows specialised variants of bn_add_words() and
+   bn_sub_words().  They have the property performing operations on
+   arrays of different sizes.  The sizes of those arrays is expressed through
+   cl, which is the common length ( basicall, min(len(a),len(b)) ), and dl,
+   which is the delta between the two lengths, calculated as len(a)-len(b).
+   All lengths are the number of BN_ULONGs...  For the operations that require
+   a result array as parameter, it must have the length cl+abs(dl).
+   These functions should probably end up in bn_asm.c as soon as there are
+   assembler counterparts for the systems that use assembler files.  */
+
+BN_ULONG bn_sub_part_words(BN_ULONG *r,
+	const BN_ULONG *a, const BN_ULONG *b,
+	int cl, int dl)
+	{
+	BN_ULONG c, t;
+
+	assert(cl >= 0);
+	c = bn_sub_words(r, a, b, cl);
+
+	if (dl == 0)
+		return c;
+
+	r += cl;
+	a += cl;
+	b += cl;
+
+	if (dl < 0)
+		{
+#ifdef BN_COUNT
+		fprintf(stderr, "  bn_sub_part_words %d + %d (dl < 0, c = %d)\n", cl, dl, c);
+#endif
+		for (;;)
+			{
+			t = b[0];
+			r[0] = (0-t-c)&BN_MASK2;
+			if (t != 0) c=1;
+			if (++dl >= 0) break;
+
+			t = b[1];
+			r[1] = (0-t-c)&BN_MASK2;
+			if (t != 0) c=1;
+			if (++dl >= 0) break;
+
+			t = b[2];
+			r[2] = (0-t-c)&BN_MASK2;
+			if (t != 0) c=1;
+			if (++dl >= 0) break;
+
+			t = b[3];
+			r[3] = (0-t-c)&BN_MASK2;
+			if (t != 0) c=1;
+			if (++dl >= 0) break;
+
+			b += 4;
+			r += 4;
+			}
+		}
+	else
+		{
+		int save_dl = dl;
+#ifdef BN_COUNT
+		fprintf(stderr, "  bn_sub_part_words %d + %d (dl > 0, c = %d)\n", cl, dl, c);
+#endif
+		while(c)
+			{
+			t = a[0];
+			r[0] = (t-c)&BN_MASK2;
+			if (t != 0) c=0;
+			if (--dl <= 0) break;
+
+			t = a[1];
+			r[1] = (t-c)&BN_MASK2;
+			if (t != 0) c=0;
+			if (--dl <= 0) break;
+
+			t = a[2];
+			r[2] = (t-c)&BN_MASK2;
+			if (t != 0) c=0;
+			if (--dl <= 0) break;
+
+			t = a[3];
+			r[3] = (t-c)&BN_MASK2;
+			if (t != 0) c=0;
+			if (--dl <= 0) break;
+
+			save_dl = dl;
+			a += 4;
+			r += 4;
+			}
+		if (dl > 0)
+			{
+#ifdef BN_COUNT
+			fprintf(stderr, "  bn_sub_part_words %d + %d (dl > 0, c == 0)\n", cl, dl);
+#endif
+			if (save_dl > dl)
+				{
+				switch (save_dl - dl)
+					{
+				case 1:
+					r[1] = a[1];
+					if (--dl <= 0) break;
+				case 2:
+					r[2] = a[2];
+					if (--dl <= 0) break;
+				case 3:
+					r[3] = a[3];
+					if (--dl <= 0) break;
+					}
+				a += 4;
+				r += 4;
+				}
+			}
+		if (dl > 0)
+			{
+#ifdef BN_COUNT
+			fprintf(stderr, "  bn_sub_part_words %d + %d (dl > 0, copy)\n", cl, dl);
+#endif
+			for(;;)
+				{
+				r[0] = a[0];
+				if (--dl <= 0) break;
+				r[1] = a[1];
+				if (--dl <= 0) break;
+				r[2] = a[2];
+				if (--dl <= 0) break;
+				r[3] = a[3];
+				if (--dl <= 0) break;
+
+				a += 4;
+				r += 4;
+				}
+			}
+		}
+	return c;
+	}
+#endif
+
+BN_ULONG bn_add_part_words(BN_ULONG *r,
+	const BN_ULONG *a, const BN_ULONG *b,
+	int cl, int dl)
+	{
+	BN_ULONG c, l, t;
+
+	assert(cl >= 0);
+	c = bn_add_words(r, a, b, cl);
+
+	if (dl == 0)
+		return c;
+
+	r += cl;
+	a += cl;
+	b += cl;
+
+	if (dl < 0)
+		{
+		int save_dl = dl;
+#ifdef BN_COUNT
+		fprintf(stderr, "  bn_add_part_words %d + %d (dl < 0, c = %d)\n", cl, dl, c);
+#endif
+		while (c)
+			{
+			l=(c+b[0])&BN_MASK2;
+			c=(l < c);
+			r[0]=l;
+			if (++dl >= 0) break;
+
+			l=(c+b[1])&BN_MASK2;
+			c=(l < c);
+			r[1]=l;
+			if (++dl >= 0) break;
+
+			l=(c+b[2])&BN_MASK2;
+			c=(l < c);
+			r[2]=l;
+			if (++dl >= 0) break;
+
+			l=(c+b[3])&BN_MASK2;
+			c=(l < c);
+			r[3]=l;
+			if (++dl >= 0) break;
+
+			save_dl = dl;
+			b+=4;
+			r+=4;
+			}
+		if (dl < 0)
+			{
+#ifdef BN_COUNT
+			fprintf(stderr, "  bn_add_part_words %d + %d (dl < 0, c == 0)\n", cl, dl);
+#endif
+			if (save_dl < dl)
+				{
+				switch (dl - save_dl)
+					{
+				case 1:
+					r[1] = b[1];
+					if (++dl >= 0) break;
+				case 2:
+					r[2] = b[2];
+					if (++dl >= 0) break;
+				case 3:
+					r[3] = b[3];
+					if (++dl >= 0) break;
+					}
+				b += 4;
+				r += 4;
+				}
+			}
+		if (dl < 0)
+			{
+#ifdef BN_COUNT
+			fprintf(stderr, "  bn_add_part_words %d + %d (dl < 0, copy)\n", cl, dl);
+#endif
+			for(;;)
+				{
+				r[0] = b[0];
+				if (++dl >= 0) break;
+				r[1] = b[1];
+				if (++dl >= 0) break;
+				r[2] = b[2];
+				if (++dl >= 0) break;
+				r[3] = b[3];
+				if (++dl >= 0) break;
+
+				b += 4;
+				r += 4;
+				}
+			}
+		}
+	else
+		{
+		int save_dl = dl;
+#ifdef BN_COUNT
+		fprintf(stderr, "  bn_add_part_words %d + %d (dl > 0)\n", cl, dl);
+#endif
+		while (c)
+			{
+			t=(a[0]+c)&BN_MASK2;
+			c=(t < c);
+			r[0]=t;
+			if (--dl <= 0) break;
+
+			t=(a[1]+c)&BN_MASK2;
+			c=(t < c);
+			r[1]=t;
+			if (--dl <= 0) break;
+
+			t=(a[2]+c)&BN_MASK2;
+			c=(t < c);
+			r[2]=t;
+			if (--dl <= 0) break;
+
+			t=(a[3]+c)&BN_MASK2;
+			c=(t < c);
+			r[3]=t;
+			if (--dl <= 0) break;
+
+			save_dl = dl;
+			a+=4;
+			r+=4;
+			}
+#ifdef BN_COUNT
+		fprintf(stderr, "  bn_add_part_words %d + %d (dl > 0, c == 0)\n", cl, dl);
+#endif
+		if (dl > 0)
+			{
+			if (save_dl > dl)
+				{
+				switch (save_dl - dl)
+					{
+				case 1:
+					r[1] = a[1];
+					if (--dl <= 0) break;
+				case 2:
+					r[2] = a[2];
+					if (--dl <= 0) break;
+				case 3:
+					r[3] = a[3];
+					if (--dl <= 0) break;
+					}
+				a += 4;
+				r += 4;
+				}
+			}
+		if (dl > 0)
+			{
+#ifdef BN_COUNT
+			fprintf(stderr, "  bn_add_part_words %d + %d (dl > 0, copy)\n", cl, dl);
+#endif
+			for(;;)
+				{
+				r[0] = a[0];
+				if (--dl <= 0) break;
+				r[1] = a[1];
+				if (--dl <= 0) break;
+				r[2] = a[2];
+				if (--dl <= 0) break;
+				r[3] = a[3];
+				if (--dl <= 0) break;
+
+				a += 4;
+				r += 4;
+				}
+			}
+		}
+	return c;
+	}
+
 #ifdef BN_RECURSION
+/* Karatsuba recursive multiplication algorithm
+ * (cf. Knuth, The Art of Computer Programming, Vol. 2) */
+
 /* r is 2*n2 words in size,
  * a and b are both n2 words in size.
  * n2 must be a power of 2.
  * We multiply and return the result.
  * t must be 2*n2 words in size
- * We calulate
+ * We calculate
  * a[0]*b[0]
  * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
  * a[1]*b[1]
  */
-void bn_mul_recursive(r,a,b,n2,t)
-BN_ULONG *r,*a,*b;
-int n2;
-BN_ULONG *t;
+void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
+	int dna, int dnb, BN_ULONG *t)
 	{
 	int n=n2/2,c1,c2;
+	int tna=n+dna, tnb=n+dnb;
 	unsigned int neg,zero;
 	BN_ULONG ln,lo,*p;
 
-#ifdef BN_COUNT
-printf(" bn_mul_recursive %d * %d\n",n2,n2);
-#endif
-#ifdef BN_MUL_COMBA
-/*	if (n2 == 4)
+# ifdef BN_COUNT
+	fprintf(stderr," bn_mul_recursive %d * %d\n",n2,n2);
+# endif
+# ifdef BN_MUL_COMBA
+#  if 0
+	if (n2 == 4)
 		{
 		bn_mul_comba4(r,a,b);
 		return;
 		}
-	else */ if (n2 == 8)
+#  endif
+	/* Only call bn_mul_comba 8 if n2 == 8 and the
+	 * two arrays are complete [steve]
+	 */
+	if (n2 == 8 && dna == 0 && dnb == 0)
 		{
 		bn_mul_comba8(r,a,b);
 		return; 
 		}
-#endif
+# endif /* BN_MUL_COMBA */
+	/* Else do normal multiply */
 	if (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL)
 		{
-		/* This should not happen */
-		bn_mul_normal(r,a,n2,b,n2);
+		bn_mul_normal(r,a,n2+dna,b,n2+dnb);
+		if ((dna + dnb) < 0)
+			memset(&r[2*n2 + dna + dnb], 0,
+				sizeof(BN_ULONG) * -(dna + dnb));
 		return;
 		}
 	/* r=(a[0]-a[1])*(b[1]-b[0]) */
-	c1=bn_cmp_words(a,&(a[n]),n);
-	c2=bn_cmp_words(&(b[n]),b,n);
+	c1=bn_cmp_part_words(a,&(a[n]),tna,n-tna);
+	c2=bn_cmp_part_words(&(b[n]),b,tnb,tnb-n);
 	zero=neg=0;
 	switch (c1*3+c2)
 		{
 	case -4:
-		bn_sub_words(t,      &(a[n]),a,      n); /* - */
-		bn_sub_words(&(t[n]),b,      &(b[n]),n); /* - */
+		bn_sub_part_words(t,      &(a[n]),a,      tna,tna-n); /* - */
+		bn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb); /* - */
 		break;
 	case -3:
 		zero=1;
 		break;
 	case -2:
-		bn_sub_words(t,      &(a[n]),a,      n); /* - */
-		bn_sub_words(&(t[n]),&(b[n]),b,      n); /* + */
+		bn_sub_part_words(t,      &(a[n]),a,      tna,tna-n); /* - */
+		bn_sub_part_words(&(t[n]),&(b[n]),b,      tnb,tnb-n); /* + */
 		neg=1;
 		break;
 	case -1:
@@ -125,21 +450,22 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
 		zero=1;
 		break;
 	case 2:
-		bn_sub_words(t,      a,      &(a[n]),n); /* + */
-		bn_sub_words(&(t[n]),b,      &(b[n]),n); /* - */
+		bn_sub_part_words(t,      a,      &(a[n]),tna,n-tna); /* + */
+		bn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb); /* - */
 		neg=1;
 		break;
 	case 3:
 		zero=1;
 		break;
 	case 4:
-		bn_sub_words(t,      a,      &(a[n]),n);
-		bn_sub_words(&(t[n]),&(b[n]),b,      n);
+		bn_sub_part_words(t,      a,      &(a[n]),tna,n-tna);
+		bn_sub_part_words(&(t[n]),&(b[n]),b,      tnb,tnb-n);
 		break;
 		}
 
-#ifdef BN_MUL_COMBA
-	if (n == 4)
+# ifdef BN_MUL_COMBA
+	if (n == 4 && dna == 0 && dnb == 0) /* XXX: bn_mul_comba4 could take
+					       extra args to do this well */
 		{
 		if (!zero)
 			bn_mul_comba4(&(t[n2]),t,&(t[n]));
@@ -149,7 +475,9 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
 		bn_mul_comba4(r,a,b);
 		bn_mul_comba4(&(r[n2]),&(a[n]),&(b[n]));
 		}
-	else if (n == 8)
+	else if (n == 8 && dna == 0 && dnb == 0) /* XXX: bn_mul_comba8 could
+						    take extra args to do this
+						    well */
 		{
 		if (!zero)
 			bn_mul_comba8(&(t[n2]),t,&(t[n]));
@@ -160,15 +488,15 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
 		bn_mul_comba8(&(r[n2]),&(a[n]),&(b[n]));
 		}
 	else
-#endif
+# endif /* BN_MUL_COMBA */
 		{
 		p= &(t[n2*2]);
 		if (!zero)
-			bn_mul_recursive(&(t[n2]),t,&(t[n]),n,p);
+			bn_mul_recursive(&(t[n2]),t,&(t[n]),n,0,0,p);
 		else
 			memset(&(t[n2]),0,n2*sizeof(BN_ULONG));
-		bn_mul_recursive(r,a,b,n,p);
-		bn_mul_recursive(&(r[n2]),&(a[n]),&(b[n]),n,p);
+		bn_mul_recursive(r,a,b,n,0,0,p);
+		bn_mul_recursive(&(r[n2]),&(a[n]),&(b[n]),n,dna,dnb,p);
 		}
 
 	/* t[32] holds (a[0]-a[1])*(b[1]-b[0]), c1 is the sign
@@ -217,88 +545,128 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
 
 /* n+tn is the word length
  * t needs to be n*4 is size, as does r */
-void bn_mul_part_recursive(r,a,b,tn,n,t)
-BN_ULONG *r,*a,*b;
-int tn,n;
-BN_ULONG *t;
+void bn_mul_part_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n,
+	     int tna, int tnb, BN_ULONG *t)
 	{
 	int i,j,n2=n*2;
-	unsigned int c1;
+	int c1,c2,neg,zero;
 	BN_ULONG ln,lo,*p;
 
-#ifdef BN_COUNT
-printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
-#endif
+# ifdef BN_COUNT
+	fprintf(stderr," bn_mul_part_recursive (%d+%d) * (%d+%d)\n",
+		tna, n, tnb, n);
+# endif
 	if (n < 8)
 		{
-		i=tn+n;
-		bn_mul_normal(r,a,i,b,i);
+		bn_mul_normal(r,a,n+tna,b,n+tnb);
 		return;
 		}
 
 	/* r=(a[0]-a[1])*(b[1]-b[0]) */
-	bn_sub_words(t,      a,      &(a[n]),n); /* + */
-	bn_sub_words(&(t[n]),b,      &(b[n]),n); /* - */
-
-/*	if (n == 4)
+	c1=bn_cmp_part_words(a,&(a[n]),tna,n-tna);
+	c2=bn_cmp_part_words(&(b[n]),b,tnb,tnb-n);
+	zero=neg=0;
+	switch (c1*3+c2)
+		{
+	case -4:
+		bn_sub_part_words(t,      &(a[n]),a,      tna,tna-n); /* - */
+		bn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb); /* - */
+		break;
+	case -3:
+		zero=1;
+		/* break; */
+	case -2:
+		bn_sub_part_words(t,      &(a[n]),a,      tna,tna-n); /* - */
+		bn_sub_part_words(&(t[n]),&(b[n]),b,      tnb,tnb-n); /* + */
+		neg=1;
+		break;
+	case -1:
+	case 0:
+	case 1:
+		zero=1;
+		/* break; */
+	case 2:
+		bn_sub_part_words(t,      a,      &(a[n]),tna,n-tna); /* + */
+		bn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb); /* - */
+		neg=1;
+		break;
+	case 3:
+		zero=1;
+		/* break; */
+	case 4:
+		bn_sub_part_words(t,      a,      &(a[n]),tna,n-tna);
+		bn_sub_part_words(&(t[n]),&(b[n]),b,      tnb,tnb-n);
+		break;
+		}
+		/* The zero case isn't yet implemented here. The speedup
+		   would probably be negligible. */
+# if 0
+	if (n == 4)
 		{
 		bn_mul_comba4(&(t[n2]),t,&(t[n]));
 		bn_mul_comba4(r,a,b);
 		bn_mul_normal(&(r[n2]),&(a[n]),tn,&(b[n]),tn);
 		memset(&(r[n2+tn*2]),0,sizeof(BN_ULONG)*(n2-tn*2));
 		}
-	else */ if (n == 8)
+	else
+# endif
+	if (n == 8)
 		{
 		bn_mul_comba8(&(t[n2]),t,&(t[n]));
 		bn_mul_comba8(r,a,b);
-		bn_mul_normal(&(r[n2]),&(a[n]),tn,&(b[n]),tn);
-		memset(&(r[n2+tn*2]),0,sizeof(BN_ULONG)*(n2-tn*2));
+		bn_mul_normal(&(r[n2]),&(a[n]),tna,&(b[n]),tnb);
+		memset(&(r[n2+tna+tnb]),0,sizeof(BN_ULONG)*(n2-tna-tnb));
 		}
 	else
 		{
 		p= &(t[n2*2]);
-		bn_mul_recursive(&(t[n2]),t,&(t[n]),n,p);
-		bn_mul_recursive(r,a,b,n,p);
+		bn_mul_recursive(&(t[n2]),t,&(t[n]),n,0,0,p);
+		bn_mul_recursive(r,a,b,n,0,0,p);
 		i=n/2;
 		/* If there is only a bottom half to the number,
 		 * just do it */
-		j=tn-i;
+		if (tna > tnb)
+			j = tna - i;
+		else
+			j = tnb - i;
 		if (j == 0)
 			{
-			bn_mul_recursive(&(r[n2]),&(a[n]),&(b[n]),i,p);
+			bn_mul_recursive(&(r[n2]),&(a[n]),&(b[n]),
+				i,tna-i,tnb-i,p);
 			memset(&(r[n2+i*2]),0,sizeof(BN_ULONG)*(n2-i*2));
 			}
 		else if (j > 0) /* eg, n == 16, i == 8 and tn == 11 */
 				{
 				bn_mul_part_recursive(&(r[n2]),&(a[n]),&(b[n]),
-					j,i,p);
-				memset(&(r[n2+tn*2]),0,
-					sizeof(BN_ULONG)*(n2-tn*2));
+					i,tna-i,tnb-i,p);
+				memset(&(r[n2+tna+tnb]),0,
+					sizeof(BN_ULONG)*(n2-tna-tnb));
 				}
 		else /* (j < 0) eg, n == 16, i == 8 and tn == 5 */
 			{
 			memset(&(r[n2]),0,sizeof(BN_ULONG)*n2);
-			if (tn < BN_MUL_RECURSIVE_SIZE_NORMAL)
+			if (tna < BN_MUL_RECURSIVE_SIZE_NORMAL
+				&& tnb < BN_MUL_RECURSIVE_SIZE_NORMAL)
 				{
-				bn_mul_normal(&(r[n2]),&(a[n]),tn,&(b[n]),tn);
+				bn_mul_normal(&(r[n2]),&(a[n]),tna,&(b[n]),tnb);
 				}
 			else
 				{
 				for (;;)
 					{
 					i/=2;
-					if (i < tn)
+					if (i < tna && i < tnb)
 						{
 						bn_mul_part_recursive(&(r[n2]),
 							&(a[n]),&(b[n]),
-							tn-i,i,p);
+							i,tna-i,tnb-i,p);
 						break;
 						}
-					else if (i == tn)
+					else if (i <= tna && i <= tnb)
 						{
 						bn_mul_recursive(&(r[n2]),
 							&(a[n]),&(b[n]),
-							i,p);
+							i,tna-i,tnb-i,p);
 						break;
 						}
 					}
@@ -312,7 +680,16 @@ printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
 	 */
 
 	c1=(int)(bn_add_words(t,r,&(r[n2]),n2));
-	c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
+
+	if (neg) /* if t[32] is negative */
+		{
+		c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
+		}
+	else
+		{
+		/* Might have a carry */
+		c1+=(int)(bn_add_words(&(t[n2]),&(t[n2]),t,n2));
+		}
 
 	/* t[32] holds (a[0]-a[1])*(b[1]-b[0])+(a[0]*b[0])+(a[1]*b[1])
 	 * r[10] holds (a[0]*b[0])
@@ -329,7 +706,7 @@ printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
 
 		/* The overflow will stop before we over write
 		 * words we should not overwrite */
-		if (ln < c1)
+		if (ln < (BN_ULONG)c1)
 			{
 			do	{
 				p++;
@@ -344,18 +721,16 @@ printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
 /* a and b must be the same size, which is n2.
  * r needs to be n2 words and t needs to be n2*2
  */
-void bn_mul_low_recursive(r,a,b,n2,t)
-BN_ULONG *r,*a,*b;
-int n2;
-BN_ULONG *t;
+void bn_mul_low_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
+	     BN_ULONG *t)
 	{
 	int n=n2/2;
 
-#ifdef BN_COUNT
-printf(" bn_mul_low_recursive %d * %d\n",n2,n2);
-#endif
+# ifdef BN_COUNT
+	fprintf(stderr," bn_mul_low_recursive %d * %d\n",n2,n2);
+# endif
 
-	bn_mul_recursive(r,a,b,n,&(t[0]));
+	bn_mul_recursive(r,a,b,n,0,0,&(t[0]));
 	if (n >= BN_MUL_LOW_RECURSIVE_SIZE_NORMAL)
 		{
 		bn_mul_low_recursive(&(t[0]),&(a[0]),&(b[n]),n,&(t[n2]));
@@ -377,20 +752,18 @@ printf(" bn_mul_low_recursive %d * %d\n",n2,n2);
  * l is the low words of the output.
  * t needs to be n2*3
  */
-void bn_mul_high(r,a,b,l,n2,t)
-BN_ULONG *r,*a,*b,*l;
-int n2;
-BN_ULONG *t;
+void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l, int n2,
+	     BN_ULONG *t)
 	{
 	int i,n;
 	int c1,c2;
 	int neg,oneg,zero;
 	BN_ULONG ll,lc,*lp,*mp;
 
-#ifdef BN_COUNT
-printf(" bn_mul_high %d * %d\n",n2,n2);
-#endif
-	n=(n2+1)/2;
+# ifdef BN_COUNT
+	fprintf(stderr," bn_mul_high %d * %d\n",n2,n2);
+# endif
+	n=n2/2;
 
 	/* Calculate (al-ah)*(bh-bl) */
 	neg=zero=0;
@@ -432,17 +805,17 @@ printf(" bn_mul_high %d * %d\n",n2,n2);
 	oneg=neg;
 	/* t[10] = (a[0]-a[1])*(b[1]-b[0]) */
 	/* r[10] = (a[1]*b[1]) */
-#ifdef BN_MUL_COMBA
+# ifdef BN_MUL_COMBA
 	if (n == 8)
 		{
 		bn_mul_comba8(&(t[0]),&(r[0]),&(r[n]));
 		bn_mul_comba8(r,&(a[n]),&(b[n]));
 		}
 	else
-#endif
+# endif
 		{
-		bn_mul_recursive(&(t[0]),&(r[0]),&(r[n]),n,&(t[n2]));
-		bn_mul_recursive(r,&(a[n]),&(b[n]),n,&(t[n2]));
+		bn_mul_recursive(&(t[0]),&(r[0]),&(r[n]),n,0,0,&(t[n2]));
+		bn_mul_recursive(r,&(a[n]),&(b[n]),n,0,0,&(t[n2]));
 		}
 
 	/* s0 == low(al*bl)
@@ -563,20 +936,23 @@ printf(" bn_mul_high %d * %d\n",n2,n2);
 			}
 		}
 	}
-#endif
+#endif /* BN_RECURSION */
 
-int BN_mul(r,a,b,ctx)
-BIGNUM *r,*a,*b;
-BN_CTX *ctx;
+int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
 	{
-	int top,i,j,k,al,bl;
-	BIGNUM *t;
-
-	t=NULL;
-	i=j=k=0;
+	int ret=0;
+	int top,al,bl;
+	BIGNUM *rr;
+#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
+	int i;
+#endif
+#ifdef BN_RECURSION
+	BIGNUM *t=NULL;
+	int j=0,k;
+#endif
 
 #ifdef BN_COUNT
-printf("BN_mul %d * %d\n",a->top,b->top);
+	fprintf(stderr,"BN_mul %d * %d\n",a->top,b->top);
 #endif
 
 	bn_check_top(a);
@@ -585,127 +961,150 @@ printf("BN_mul %d * %d\n",a->top,b->top);
 
 	al=a->top;
 	bl=b->top;
-	r->neg=a->neg^b->neg;
 
 	if ((al == 0) || (bl == 0))
 		{
-		BN_zero(r);
+		if (!BN_zero(r)) goto err;
 		return(1);
 		}
 	top=al+bl;
+
+	BN_CTX_start(ctx);
+	if ((r == a) || (r == b))
+		{
+		if ((rr = BN_CTX_get(ctx)) == NULL) goto err;
+		}
+	else
+		rr = r;
+	rr->neg=a->neg^b->neg;
+
 #if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
-	if (al == bl)
+	i = al-bl;
+#endif
+#ifdef BN_MUL_COMBA
+	if (i == 0)
 		{
-#  ifdef BN_MUL_COMBA
-/*		if (al == 4)
+# if 0
+		if (al == 4)
 			{
-			if (bn_wexpand(r,8) == NULL) return(0);
-			r->top=8;
-			bn_mul_comba4(r->d,a->d,b->d);
+			if (bn_wexpand(rr,8) == NULL) goto err;
+			rr->top=8;
+			bn_mul_comba4(rr->d,a->d,b->d);
 			goto end;
 			}
-		else */ if (al == 8)
+# endif
+		if (al == 8)
 			{
-			if (bn_wexpand(r,16) == NULL) return(0);
-			r->top=16;
-			bn_mul_comba8(r->d,a->d,b->d);
+			if (bn_wexpand(rr,16) == NULL) goto err;
+			rr->top=16;
+			bn_mul_comba8(rr->d,a->d,b->d);
 			goto end;
 			}
-		else
-#  endif
+		}
+#endif /* BN_MUL_COMBA */
 #ifdef BN_RECURSION
-		if (al < BN_MULL_SIZE_NORMAL)
-#endif
+	if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL))
+		{
+		if (i >= -1 && i <= 1)
 			{
-			if (bn_wexpand(r,top) == NULL) return(0);
-			r->top=top;
-			bn_mul_normal(r->d,a->d,al,b->d,bl);
+			int sav_j =0;
+			/* Find out the power of two lower or equal
+			   to the longest of the two numbers */
+			if (i >= 0)
+				{
+				j = BN_num_bits_word((BN_ULONG)al);
+				}
+			if (i == -1)
+				{
+				j = BN_num_bits_word((BN_ULONG)bl);
+				}
+			sav_j = j;
+			j = 1<<(j-1);
+			assert(j <= al || j <= bl);
+			k = j+j;
+			t = BN_CTX_get(ctx);
+			if (al > j || bl > j)
+				{
+				bn_wexpand(t,k*4);
+				bn_wexpand(rr,k*4);
+				bn_mul_part_recursive(rr->d,a->d,b->d,
+					j,al-j,bl-j,t->d);
+				}
+			else	/* al <= j || bl <= j */
+				{
+				bn_wexpand(t,k*2);
+				bn_wexpand(rr,k*2);
+				bn_mul_recursive(rr->d,a->d,b->d,
+					j,al-j,bl-j,t->d);
+				}
+			rr->top=top;
 			goto end;
 			}
-#  ifdef BN_RECURSION
-		goto symetric;
-#  endif
-		}
-#endif
-#ifdef BN_RECURSION
-	else if ((al < BN_MULL_SIZE_NORMAL) || (bl < BN_MULL_SIZE_NORMAL))
-		{
-		if (bn_wexpand(r,top) == NULL) return(0);
-		r->top=top;
-		bn_mul_normal(r->d,a->d,al,b->d,bl);
-		goto end;
-		}
-	else
-		{
-		i=(al-bl);
-		if ((i ==  1) && !BN_get_flags(b,BN_FLG_STATIC_DATA))
+#if 0
+		if (i == 1 && !BN_get_flags(b,BN_FLG_STATIC_DATA))
 			{
-			bn_wexpand(b,al);
-			b->d[bl]=0;
+			BIGNUM *tmp_bn = (BIGNUM *)b;
+			if (bn_wexpand(tmp_bn,al) == NULL) goto err;
+			tmp_bn->d[bl]=0;
 			bl++;
-			goto symetric;
+			i--;
 			}
-		else if ((i ==  -1) && !BN_get_flags(a,BN_FLG_STATIC_DATA))
+		else if (i == -1 && !BN_get_flags(a,BN_FLG_STATIC_DATA))
 			{
-			bn_wexpand(a,bl);
-			a->d[al]=0;
+			BIGNUM *tmp_bn = (BIGNUM *)a;
+			if (bn_wexpand(tmp_bn,bl) == NULL) goto err;
+			tmp_bn->d[al]=0;
 			al++;
-			goto symetric;
-			}
-		}
-#endif
-
-	/* asymetric and >= 4 */ 
-	if (bn_wexpand(r,top) == NULL) return(0);
-	r->top=top;
-	bn_mul_normal(r->d,a->d,al,b->d,bl);
-
-#ifdef BN_RECURSION
-	if (0)
-		{
-symetric:
-		/* symetric and > 4 */
-		/* 16 or larger */
-		j=BN_num_bits_word((BN_ULONG)al);
-		j=1<<(j-1);
-		k=j+j;
-		t= &(ctx->bn[ctx->tos]);
-		if (al == j) /* exact multiple */
-			{
-			bn_wexpand(t,k*2);
-			bn_wexpand(r,k*2);
-			bn_mul_recursive(r->d,a->d,b->d,al,t->d);
+			i++;
 			}
-		else
+		if (i == 0)
 			{
-			bn_wexpand(a,k);
-			bn_wexpand(b,k);
-			bn_wexpand(t,k*4);
-			bn_wexpand(r,k*4);
-			for (i=a->top; i<k; i++)
-				a->d[i]=0;
-			for (i=b->top; i<k; i++)
-				b->d[i]=0;
-			bn_mul_part_recursive(r->d,a->d,b->d,al-j,j,t->d);
+			/* symmetric and > 4 */
+			/* 16 or larger */
+			j=BN_num_bits_word((BN_ULONG)al);
+			j=1<<(j-1);
+			k=j+j;
+			t = BN_CTX_get(ctx);
+			if (al == j) /* exact multiple */
+				{
+				if (bn_wexpand(t,k*2) == NULL) goto err;
+				if (bn_wexpand(rr,k*2) == NULL) goto err;
+				bn_mul_recursive(rr->d,a->d,b->d,al,t->d);
+				}
+			else
+				{
+				if (bn_wexpand(t,k*4) == NULL) goto err;
+				if (bn_wexpand(rr,k*4) == NULL) goto err;
+				bn_mul_part_recursive(rr->d,a->d,b->d,al-j,j,t->d);
+				}
+			rr->top=top;
+			goto end;
 			}
-		r->top=top;
-		}
 #endif
+		}
+#endif /* BN_RECURSION */
+	if (bn_wexpand(rr,top) == NULL) goto err;
+	rr->top=top;
+	bn_mul_normal(rr->d,a->d,al,b->d,bl);
+
+#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
 end:
-	bn_fix_top(r);
-	return(1);
+#endif
+	bn_correct_top(rr);
+	if (r != rr) BN_copy(r,rr);
+	ret=1;
+err:
+	BN_CTX_end(ctx);
+	bn_check_top(r);
+	return(ret);
 	}
 
-void bn_mul_normal(r,a,na,b,nb)
-BN_ULONG *r,*a;
-int na;
-BN_ULONG *b;
-int nb;
+void bn_mul_normal(BN_ULONG *r, BN_ULONG *a, int na, BN_ULONG *b, int nb)
 	{
 	BN_ULONG *rr;
 
 #ifdef BN_COUNT
-printf(" bn_mul_normal %d * %d\n",na,nb);
+	fprintf(stderr," bn_mul_normal %d * %d\n",na,nb);
 #endif
 
 	if (na < nb)
@@ -718,7 +1117,13 @@ printf(" bn_mul_normal %d * %d\n",na,nb);
 
 		}
 	rr= &(r[na]);
-	rr[0]=bn_mul_words(r,a,na,b[0]);
+	if (nb <= 0)
+		{
+		(void)bn_mul_words(r,a,na,0);
+		return;
+		}
+	else
+		rr[0]=bn_mul_words(r,a,na,b[0]);
 
 	for (;;)
 		{
@@ -736,12 +1141,10 @@ printf(" bn_mul_normal %d * %d\n",na,nb);
 		}
 	}
 
-void bn_mul_low_normal(r,a,b,n)
-BN_ULONG *r,*a,*b;
-int n;
+void bn_mul_low_normal(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n)
 	{
 #ifdef BN_COUNT
-printf(" bn_mul_low_normal %d * %d\n",n,n);
+	fprintf(stderr," bn_mul_low_normal %d * %d\n",n,n);
 #endif
 	bn_mul_words(r,a,n,b[0]);
 
@@ -759,4 +1162,3 @@ printf(" bn_mul_low_normal %d * %d\n",n,n);
 		b+=4;
 		}
 	}
-