From 020fc820dc90dbbcf0d7e3f3345af9e44cf905a7 Mon Sep 17 00:00:00 2001
From: Richard Levitte <levitte@openssl.org>
Date: Mon, 6 Nov 2000 21:15:54 +0000
Subject: Constify the BIGNUM routines a bit more.  The only trouble were the
 two functions that did expansion on in parameters (BN_mul() and BN_sqr()). 
 The problem was solved by making bn_dup_expand() which is a mix of
 bn_expand2() and BN_dup().

---
 crypto/bn/bn.h       |  55 ++++++-----
 crypto/bn/bn_exp.c   |  16 ++--
 crypto/bn/bn_exp2.c  |   7 +-
 crypto/bn/bn_gcd.c   |   3 +-
 crypto/bn/bn_lib.c   | 262 ++++++++++++++++++++++++++++++---------------------
 crypto/bn/bn_mont.c  |   2 +-
 crypto/bn/bn_mul.c   |  32 ++++---
 crypto/bn/bn_prime.c |  17 ++--
 crypto/bn/bn_recp.c  |  16 ++--
 crypto/bn/bn_shift.c |   6 +-
 crypto/bn/bn_sqr.c   |   9 +-
 crypto/bn/bntest.c   |   1 +
 12 files changed, 248 insertions(+), 178 deletions(-)

(limited to 'crypto')

diff --git a/crypto/bn/bn.h b/crypto/bn/bn.h
index 1eb8395b25..dad488fafb 100644
--- a/crypto/bn/bn.h
+++ b/crypto/bn/bn.h
@@ -345,33 +345,35 @@ int	BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
 int	BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx);
 int	BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
 	       BN_CTX *ctx);
-int	BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
-int	BN_sqr(BIGNUM *r, BIGNUM *a,BN_CTX *ctx);
+int	BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
+int	BN_sqr(BIGNUM *r, const BIGNUM *a,BN_CTX *ctx);
 BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w);
 BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w);
 int	BN_mul_word(BIGNUM *a, BN_ULONG w);
 int	BN_add_word(BIGNUM *a, BN_ULONG w);
 int	BN_sub_word(BIGNUM *a, BN_ULONG w);
 int	BN_set_word(BIGNUM *a, BN_ULONG w);
-BN_ULONG BN_get_word(BIGNUM *a);
+BN_ULONG BN_get_word(const BIGNUM *a);
 int	BN_cmp(const BIGNUM *a, const BIGNUM *b);
 void	BN_free(BIGNUM *a);
 int	BN_is_bit_set(const BIGNUM *a, int n);
 int	BN_lshift(BIGNUM *r, const BIGNUM *a, int n);
-int	BN_lshift1(BIGNUM *r, BIGNUM *a);
-int	BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p,BN_CTX *ctx);
-int	BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
-		   const BIGNUM *m,BN_CTX *ctx);
-int	BN_mod_exp_mont(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
-			const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
+int	BN_lshift1(BIGNUM *r, const BIGNUM *a);
+int	BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,BN_CTX *ctx);
+int	BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
+	const BIGNUM *m,BN_CTX *ctx);
+int	BN_mod_exp_mont(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
+	const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
 int	BN_mod_exp_mont_word(BIGNUM *r, BN_ULONG a, const BIGNUM *p,
-			const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
-int	BN_mod_exp2_mont(BIGNUM *r, BIGNUM *a1, BIGNUM *p1,BIGNUM *a2,
-		BIGNUM *p2,BIGNUM *m,BN_CTX *ctx,BN_MONT_CTX *m_ctx);
-int	BN_mod_exp_simple(BIGNUM *r, BIGNUM *a, BIGNUM *p,
-	BIGNUM *m,BN_CTX *ctx);
+	const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
+int	BN_mod_exp2_mont(BIGNUM *r, const BIGNUM *a1, const BIGNUM *p1,
+	const BIGNUM *a2, const BIGNUM *p2,const BIGNUM *m,
+	BN_CTX *ctx,BN_MONT_CTX *m_ctx);
+int	BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
+	const BIGNUM *m,BN_CTX *ctx);
 int	BN_mask_bits(BIGNUM *a,int n);
-int	BN_mod_mul(BIGNUM *ret, BIGNUM *a, BIGNUM *b, const BIGNUM *m, BN_CTX *ctx);
+int	BN_mod_mul(BIGNUM *ret, const BIGNUM *a, const BIGNUM *b,
+	const BIGNUM *m, BN_CTX *ctx);
 #ifndef NO_FP_API
 int	BN_print_fp(FILE *fp, const BIGNUM *a);
 #endif
@@ -380,9 +382,9 @@ int	BN_print(BIO *fp, const BIGNUM *a);
 #else
 int	BN_print(void *fp, const BIGNUM *a);
 #endif
-int	BN_reciprocal(BIGNUM *r, BIGNUM *m, int len, BN_CTX *ctx);
-int	BN_rshift(BIGNUM *r, BIGNUM *a, int n);
-int	BN_rshift1(BIGNUM *r, BIGNUM *a);
+int	BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx);
+int	BN_rshift(BIGNUM *r, const BIGNUM *a, int n);
+int	BN_rshift1(BIGNUM *r, const BIGNUM *a);
 void	BN_clear(BIGNUM *a);
 BIGNUM *BN_dup(const BIGNUM *a);
 int	BN_ucmp(const BIGNUM *a, const BIGNUM *b);
@@ -393,9 +395,11 @@ char *	BN_bn2dec(const BIGNUM *a);
 int 	BN_hex2bn(BIGNUM **a, const char *str);
 int 	BN_dec2bn(BIGNUM **a, const char *str);
 int	BN_gcd(BIGNUM *r,BIGNUM *in_a,BIGNUM *in_b,BN_CTX *ctx);
-BIGNUM *BN_mod_inverse(BIGNUM *ret,BIGNUM *a, const BIGNUM *n,BN_CTX *ctx);
-BIGNUM *BN_generate_prime(BIGNUM *ret,int bits,int safe,BIGNUM *add,
-		BIGNUM *rem,void (*callback)(int,int,void *),void *cb_arg);
+BIGNUM *BN_mod_inverse(BIGNUM *ret,
+	const BIGNUM *a, const BIGNUM *n,BN_CTX *ctx);
+BIGNUM *BN_generate_prime(BIGNUM *ret,int bits,int safe,
+	const BIGNUM *add, const BIGNUM *rem,
+	void (*callback)(int,int,void *),void *cb_arg);
 int	BN_is_prime(const BIGNUM *p,int nchecks,
 		void (*callback)(int,int,void *),
 		BN_CTX *ctx,void *cb_arg);
@@ -406,8 +410,8 @@ void	ERR_load_BN_strings(void );
 
 BN_MONT_CTX *BN_MONT_CTX_new(void );
 void BN_MONT_CTX_init(BN_MONT_CTX *ctx);
-int BN_mod_mul_montgomery(BIGNUM *r,BIGNUM *a,BIGNUM *b,BN_MONT_CTX *mont,
-			  BN_CTX *ctx);
+int BN_mod_mul_montgomery(BIGNUM *r,const BIGNUM *a,const BIGNUM *b,
+	BN_MONT_CTX *mont, BN_CTX *ctx);
 int BN_from_montgomery(BIGNUM *r,BIGNUM *a,BN_MONT_CTX *mont,BN_CTX *ctx);
 void BN_MONT_CTX_free(BN_MONT_CTX *mont);
 int BN_MONT_CTX_set(BN_MONT_CTX *mont,const BIGNUM *modulus,BN_CTX *ctx);
@@ -426,11 +430,11 @@ void	BN_RECP_CTX_init(BN_RECP_CTX *recp);
 BN_RECP_CTX *BN_RECP_CTX_new(void);
 void	BN_RECP_CTX_free(BN_RECP_CTX *recp);
 int	BN_RECP_CTX_set(BN_RECP_CTX *recp,const BIGNUM *rdiv,BN_CTX *ctx);
-int	BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y,
+int	BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y,
 		BN_RECP_CTX *recp,BN_CTX *ctx);
 int	BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 			const BIGNUM *m, BN_CTX *ctx);
-int	BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m,
+int	BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
 		BN_RECP_CTX *recp, BN_CTX *ctx);
 
 /* library internal functions */
@@ -439,6 +443,7 @@ int	BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m,
 	(a):bn_expand2((a),(bits)/BN_BITS2+1))
 #define bn_wexpand(a,words) (((words) <= (a)->dmax)?(a):bn_expand2((a),(words)))
 BIGNUM *bn_expand2(BIGNUM *a, int words);
+BIGNUM *bn_dup_expand(const BIGNUM *a, int words);
 
 #define bn_fix_top(a) \
         { \
diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index d2c91628ac..74b1f0e89e 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -117,7 +117,8 @@
 #define TABLE_SIZE	32
 
 /* slow but works */
-int BN_mod_mul(BIGNUM *ret, BIGNUM *a, BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
+int BN_mod_mul(BIGNUM *ret, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
+	BN_CTX *ctx)
 	{
 	BIGNUM *t;
 	int r=0;
@@ -141,7 +142,7 @@ err:
 
 
 /* this one works - simple but works */
-int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx)
+int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
 	{
 	int i,bits,ret=0;
 	BIGNUM *v,*rr;
@@ -176,7 +177,7 @@ err:
 	}
 
 
-int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
+int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
 	       BN_CTX *ctx)
 	{
 	int ret;
@@ -325,13 +326,13 @@ err:
 	}
 
 
-int BN_mod_exp_mont(BIGNUM *rr, BIGNUM *a, const BIGNUM *p,
+int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		    const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
 	{
 	int i,j,bits,ret=0,wstart,wend,window,wvalue;
 	int start=1,ts=0;
 	BIGNUM *d,*r;
-	BIGNUM *aa;
+	const BIGNUM *aa;
 	BIGNUM val[TABLE_SIZE];
 	BN_MONT_CTX *mont=NULL;
 
@@ -590,8 +591,9 @@ err:
 
 
 /* The old fallback, simple version :-) */
-int BN_mod_exp_simple(BIGNUM *r, BIGNUM *a, BIGNUM *p, BIGNUM *m,
-	     BN_CTX *ctx)
+int BN_mod_exp_simple(BIGNUM *r,
+	const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
+	BN_CTX *ctx)
 	{
 	int i,j,bits,ret=0,wstart,wend,window,wvalue,ts=0;
 	int start=1;
diff --git a/crypto/bn/bn_exp2.c b/crypto/bn/bn_exp2.c
index 29029f4c72..70c4d83a79 100644
--- a/crypto/bn/bn_exp2.c
+++ b/crypto/bn/bn_exp2.c
@@ -115,13 +115,14 @@
 
 #define TABLE_SIZE	32
 
-int BN_mod_exp2_mont(BIGNUM *rr, BIGNUM *a1, BIGNUM *p1, BIGNUM *a2,
-	     BIGNUM *p2, BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
+int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
+	const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
+	BN_CTX *ctx, BN_MONT_CTX *in_mont)
 	{
 	int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
 	int r_is_one=1,ts1=0,ts2=0;
 	BIGNUM *d,*r;
-	BIGNUM *a_mod_m;
+	const BIGNUM *a_mod_m;
 	BIGNUM val1[TABLE_SIZE], val2[TABLE_SIZE];
 	BN_MONT_CTX *mont=NULL;
 
diff --git a/crypto/bn/bn_gcd.c b/crypto/bn/bn_gcd.c
index 398207196b..61c431fc7b 100644
--- a/crypto/bn/bn_gcd.c
+++ b/crypto/bn/bn_gcd.c
@@ -144,7 +144,8 @@ err:
 	}
 
 /* solves ax == 1 (mod n) */
-BIGNUM *BN_mod_inverse(BIGNUM *in, BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
+BIGNUM *BN_mod_inverse(BIGNUM *in,
+	const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
 	{
 	BIGNUM *A,*B,*X,*Y,*M,*D,*R=NULL;
 	BIGNUM *T,*ret=NULL;
diff --git a/crypto/bn/bn_lib.c b/crypto/bn/bn_lib.c
index b6b0ce4b3c..3e4965d695 100644
--- a/crypto/bn/bn_lib.c
+++ b/crypto/bn/bn_lib.c
@@ -304,42 +304,35 @@ BIGNUM *BN_new(void)
 	return(ret);
 	}
 
-/* This is an internal function that should not be used in applications.
- * It ensures that 'b' has enough room for a 'words' word number number.
- * It is mostly used by the various BIGNUM routines. If there is an error,
- * NULL is returned. If not, 'b' is returned. */
-
-BIGNUM *bn_expand2(BIGNUM *b, int words)
+/* This is used both by bn_expand2() and bn_dup_expand() */
+/* The caller MUST check that words > b->dmax before calling this */
+static BN_ULONG *internal_bn_expand(const BIGNUM *b, int words)
 	{
-	BN_ULONG *A,*a;
+	BN_ULONG *A,*a = NULL;
 	const BN_ULONG *B;
 	int i;
 
-	bn_check_top(b);
-
-	if (words > b->dmax)
+	bn_check_top(b);	
+	if (BN_get_flags(b,BN_FLG_STATIC_DATA))
 		{
-		bn_check_top(b);	
-		if (BN_get_flags(b,BN_FLG_STATIC_DATA))
-			{
-			BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
-			return(NULL);
-			}
-		a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1));
-		if (A == NULL)
-			{
-			BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE);
-			return(NULL);
-			}
+		BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
+		return(NULL);
+		}
+	a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1));
+	if (A == NULL)
+		{
+		BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE);
+		return(NULL);
+		}
 #if 1
-		B=b->d;
-		/* Check if the previous number needs to be copied */
-		if (B != NULL)
-			{
+	B=b->d;
+	/* Check if the previous number needs to be copied */
+	if (B != NULL)
+		{
 #if 0
-			/* This lot is an unrolled loop to copy b->top 
-			 * BN_ULONGs from B to A
-			 */
+		/* This lot is an unrolled loop to copy b->top 
+		 * BN_ULONGs from B to A
+		 */
 /*
  * I have nothing against unrolling but it's usually done for
  * several reasons, namely:
@@ -363,94 +356,145 @@ BIGNUM *bn_expand2(BIGNUM *b, int words)
  *
  *					<appro@fy.chalmers.se>
  */
-			for (i=b->top&(~7); i>0; i-=8)
-				{
-				A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
-				A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7];
-				A+=8;
-				B+=8;
-				}
-			switch (b->top&7)
-				{
-			case 7:
-				A[6]=B[6];
-			case 6:
-				A[5]=B[5];
-			case 5:
-				A[4]=B[4];
-			case 4:
-				A[3]=B[3];
-			case 3:
-				A[2]=B[2];
-			case 2:
-				A[1]=B[1];
-			case 1:
-				A[0]=B[0];
-			case 0:
-				/* I need the 'case 0' entry for utrix cc.
-				 * If the optimizer is turned on, it does the
-				 * switch table by doing
-				 * a=top&7
-				 * a--;
-				 * goto jump_table[a];
-				 * If top is 0, this makes us jump to 0xffffffc 
-				 * which is rather bad :-(.
-				 * eric 23-Apr-1998
-				 */
-				;
-				}
+		for (i=b->top&(~7); i>0; i-=8)
+			{
+			A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
+			A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7];
+			A+=8;
+			B+=8;
+			}
+		switch (b->top&7)
+			{
+		case 7:
+			A[6]=B[6];
+		case 6:
+			A[5]=B[5];
+		case 5:
+			A[4]=B[4];
+		case 4:
+			A[3]=B[3];
+		case 3:
+			A[2]=B[2];
+		case 2:
+			A[1]=B[1];
+		case 1:
+			A[0]=B[0];
+		case 0:
+			/* I need the 'case 0' entry for utrix cc.
+			 * If the optimizer is turned on, it does the
+			 * switch table by doing
+			 * a=top&7
+			 * a--;
+			 * goto jump_table[a];
+			 * If top is 0, this makes us jump to 0xffffffc 
+			 * which is rather bad :-(.
+			 * eric 23-Apr-1998
+			 */
+			;
+			}
 #else
-			for (i=b->top>>2; i>0; i--,A+=4,B+=4)
-				{
-				/*
-				 * The fact that the loop is unrolled
-				 * 4-wise is a tribute to Intel. It's
-				 * the one that doesn't have enough
-				 * registers to accomodate more data.
-				 * I'd unroll it 8-wise otherwise:-)
-				 *
-				 *		<appro@fy.chalmers.se>
-				 */
-				BN_ULONG a0,a1,a2,a3;
-				a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
-				A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
-				}
-			switch (b->top&3)
-				{
-				case 3:	A[2]=B[2];
-				case 2:	A[1]=B[1];
-				case 1:	A[0]=B[0];
-				case 0:	; /* ultrix cc workaround, see above */
-				}
-#endif
-			OPENSSL_free(b->d);
+		for (i=b->top>>2; i>0; i--,A+=4,B+=4)
+			{
+			/*
+			 * The fact that the loop is unrolled
+			 * 4-wise is a tribute to Intel. It's
+			 * the one that doesn't have enough
+			 * registers to accomodate more data.
+			 * I'd unroll it 8-wise otherwise:-)
+			 *
+			 *		<appro@fy.chalmers.se>
+			 */
+			BN_ULONG a0,a1,a2,a3;
+			a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
+			A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
 			}
-
-		b->d=a;
-		b->dmax=words;
-
-		/* Now need to zero any data between b->top and b->max */
-
-		A= &(b->d[b->top]);
-		for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8)
+		switch (b->top&3)
 			{
-			A[0]=0; A[1]=0; A[2]=0; A[3]=0;
-			A[4]=0; A[5]=0; A[6]=0; A[7]=0;
+		case 3:	A[2]=B[2];
+		case 2:	A[1]=B[1];
+		case 1:	A[0]=B[0];
+		case 0:	; /* ultrix cc workaround, see above */
 			}
-		for (i=(b->dmax - b->top)&7; i>0; i--,A++)
-			A[0]=0;
+#endif
+		}
+
+	/* Now need to zero any data between b->top and b->max */
+
+	A= &(a[b->top]);
+	for (i=(words - b->top)>>3; i>0; i--,A+=8)
+		{
+		A[0]=0; A[1]=0; A[2]=0; A[3]=0;
+		A[4]=0; A[5]=0; A[6]=0; A[7]=0;
+		}
+	for (i=(words - b->top)&7; i>0; i--,A++)
+		A[0]=0;
 #else
-			memset(A,0,sizeof(BN_ULONG)*(words+1));
-			memcpy(A,b->d,sizeof(b->d[0])*b->top);
-			b->d=a;
-			b->max=words;
+	memset(A,0,sizeof(BN_ULONG)*(words+1));
+	memcpy(A,b->d,sizeof(b->d[0])*b->top);
 #endif
 		
-/*		memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */
-/*	{ int i; for (i=b->max; i<words+1; i++) p[i]=i;} */
+	return(a);
+	}
 
+/* This is an internal function that can be used instead of bn_expand2()
+ * when there is a need to copy BIGNUMs instead of only expanding the
+ * data part, while still expanding them.
+ * Especially useful when needing to expand BIGNUMs that are declared
+ * 'const' and should therefore not be changed.
+ * The reason to use this instead of a BN_dup() followed by a bn_expand2()
+ * is memory allocation overhead.  A BN_dup() followed by a bn_expand2()
+ * will allocate new memory for the BIGNUM data twice, and free it once,
+ * while bn_dup_expand() makes sure allocation is made only once.
+ */
+
+BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
+	{
+	BIGNUM *r = NULL;
+
+	if (words > b->dmax)
+		{
+		BN_ULONG *a = internal_bn_expand(b, words);
+
+		if (a)
+			{
+			r = BN_new();
+			r->top = b->top;
+			r->dmax = words;
+			r->neg = b->neg;
+			r->d = a;
+			}
+		/* Otherwise, there was an error in allocation in
+		   internal_bn_expand(), and NULL should be returned */
+		}
+	else
+		{
+		r = BN_dup(b);
+		}
+
+	return r;
+	}
+
+/* This is an internal function that should not be used in applications.
+ * It ensures that 'b' has enough room for a 'words' word number number.
+ * It is mostly used by the various BIGNUM routines. If there is an error,
+ * NULL is returned. If not, 'b' is returned. */
+
+BIGNUM *bn_expand2(BIGNUM *b, int words)
+	{
+	if (words > b->dmax)
+		{
+		BN_ULONG *a = internal_bn_expand(b, words);
+
+		if (a)
+			{
+			OPENSSL_free(b->d);
+			b->d=a;
+			b->dmax=words;
+			}
+		else
+			b = NULL;
 		}
-	return(b);
+	return b;
 	}
 
 BIGNUM *BN_dup(const BIGNUM *a)
@@ -513,7 +557,7 @@ void BN_clear(BIGNUM *a)
 	a->neg=0;
 	}
 
-BN_ULONG BN_get_word(BIGNUM *a)
+BN_ULONG BN_get_word(const BIGNUM *a)
 	{
 	int i,n;
 	BN_ULONG ret=0;
diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index 8cf1febacc..202eec4462 100644
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -69,7 +69,7 @@
 
 #define MONT_WORD /* use the faster word-based algorithm */
 
-int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
+int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
 			  BN_MONT_CTX *mont, BN_CTX *ctx)
 	{
 	BIGNUM *tmp,*tmp2;
diff --git a/crypto/bn/bn_mul.c b/crypto/bn/bn_mul.c
index 3e8d8b9567..aed7528182 100644
--- a/crypto/bn/bn_mul.c
+++ b/crypto/bn/bn_mul.c
@@ -608,7 +608,7 @@ void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l, int n2,
 	}
 #endif /* BN_RECURSION */
 
-int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
+int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
 	{
 	int top,al,bl;
 	BIGNUM *rr;
@@ -620,6 +620,7 @@ int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
 	BIGNUM *t;
 	int j,k;
 #endif
+	BIGNUM *free_a = NULL, *free_b = NULL;
 
 #ifdef BN_COUNT
 	printf("BN_mul %d * %d\n",a->top,b->top);
@@ -677,17 +678,21 @@ int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
 		{
 		if (i == 1 && !BN_get_flags(b,BN_FLG_STATIC_DATA))
 			{
-			bn_wexpand(b,al);
-			b->d[bl]=0;
+			BIGNUM *tmp_bn = free_b;
+			b = free_b = bn_dup_expand(b,al);
+			free_b->d[bl]=0;
 			bl++;
 			i--;
+			if (tmp_bn) BN_free(tmp_bn);
 			}
 		else if (i == -1 && !BN_get_flags(a,BN_FLG_STATIC_DATA))
 			{
-			bn_wexpand(a,bl);
-			a->d[al]=0;
+			BIGNUM *tmp_bn = free_a;
+			a = free_a = bn_dup_expand(a,bl);
+			free_a->d[al]=0;
 			al++;
 			i++;
+			if (tmp_bn) BN_free(tmp_bn);
 			}
 		if (i == 0)
 			{
@@ -705,14 +710,17 @@ int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
 				}
 			else
 				{
-				bn_wexpand(a,k);
-				bn_wexpand(b,k);
+				BIGNUM *tmp_a = free_a,*tmp_b = free_b;
+				a = free_a = bn_dup_expand(a,k);
+				b = free_b = bn_dup_expand(b,k);
+				if (tmp_a) BN_free(tmp_a);
+				if (tmp_b) BN_free(tmp_b);
 				bn_wexpand(t,k*4);
 				bn_wexpand(rr,k*4);
-				for (i=a->top; i<k; i++)
-					a->d[i]=0;
-				for (i=b->top; i<k; i++)
-					b->d[i]=0;
+				for (i=free_a->top; i<k; i++)
+					free_a->d[i]=0;
+				for (i=free_b->top; i<k; i++)
+					free_b->d[i]=0;
 				bn_mul_part_recursive(rr->d,a->d,b->d,al-j,j,t->d);
 				}
 			rr->top=top;
@@ -731,6 +739,8 @@ end:
 	if (r != rr) BN_copy(r,rr);
 	ret=1;
 err:
+	if (free_a) BN_free(free_a);
+	if (free_b) BN_free(free_b);
 	BN_CTX_end(ctx);
 	return(ret);
 	}
diff --git a/crypto/bn/bn_prime.c b/crypto/bn/bn_prime.c
index a5f01b92eb..b75e58c6ae 100644
--- a/crypto/bn/bn_prime.c
+++ b/crypto/bn/bn_prime.c
@@ -125,12 +125,13 @@ static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
 	const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont);
 static int probable_prime(BIGNUM *rnd, int bits);
 static int probable_prime_dh(BIGNUM *rnd, int bits,
-	BIGNUM *add, BIGNUM *rem, BN_CTX *ctx);
+	const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
 static int probable_prime_dh_safe(BIGNUM *rnd, int bits,
-	BIGNUM *add, BIGNUM *rem, BN_CTX *ctx);
+	const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
 
-BIGNUM *BN_generate_prime(BIGNUM *ret, int bits, int safe, BIGNUM *add,
-	     BIGNUM *rem, void (*callback)(int,int,void *), void *cb_arg)
+BIGNUM *BN_generate_prime(BIGNUM *ret, int bits, int safe,
+	const BIGNUM *add, const BIGNUM *rem,
+	void (*callback)(int,int,void *), void *cb_arg)
 	{
 	BIGNUM *rnd=NULL;
 	BIGNUM t;
@@ -376,8 +377,8 @@ again:
 	return(1);
 	}
 
-static int probable_prime_dh(BIGNUM *rnd, int bits, BIGNUM *add, BIGNUM *rem,
-	     BN_CTX *ctx)
+static int probable_prime_dh(BIGNUM *rnd, int bits,
+	const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx)
 	{
 	int i,ret=0;
 	BIGNUM *t1;
@@ -413,8 +414,8 @@ err:
 	return(ret);
 	}
 
-static int probable_prime_dh_safe(BIGNUM *p, int bits, BIGNUM *padd,
-	     BIGNUM *rem, BN_CTX *ctx)
+static int probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd,
+	const BIGNUM *rem, BN_CTX *ctx)
 	{
 	int i,ret=0;
 	BIGNUM *t1,*qadd,*q;
diff --git a/crypto/bn/bn_recp.c b/crypto/bn/bn_recp.c
index d019941d6b..a175e1c5f2 100644
--- a/crypto/bn/bn_recp.c
+++ b/crypto/bn/bn_recp.c
@@ -100,11 +100,12 @@ int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
 	return(1);
 	}
 
-int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
-	     BN_CTX *ctx)
+int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y,
+	BN_RECP_CTX *recp, BN_CTX *ctx)
 	{
 	int ret=0;
 	BIGNUM *a;
+	const BIGNUM *ca;
 
 	BN_CTX_start(ctx);
 	if ((a = BN_CTX_get(ctx)) == NULL) goto err;
@@ -114,19 +115,20 @@ int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
 			{ if (!BN_sqr(a,x,ctx)) goto err; }
 		else
 			{ if (!BN_mul(a,x,y,ctx)) goto err; }
+		ca = a;
 		}
 	else
-		a=x; /* Just do the mod */
+		ca=x; /* Just do the mod */
 
-	BN_div_recp(NULL,r,a,recp,ctx);
+	BN_div_recp(NULL,r,ca,recp,ctx);
 	ret=1;
 err:
 	BN_CTX_end(ctx);
 	return(ret);
 	}
 
-int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
-	     BN_CTX *ctx)
+int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
+	BN_RECP_CTX *recp, BN_CTX *ctx)
 	{
 	int i,j,ret=0;
 	BIGNUM *a,*b,*d,*r;
@@ -201,7 +203,7 @@ err:
  * We actually calculate with an extra word of precision, so
  * we can do faster division if the remainder is not required.
  */
-int BN_reciprocal(BIGNUM *r, BIGNUM *m, int len, BN_CTX *ctx)
+int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
 	{
 	int ret= -1;
 	BIGNUM t;
diff --git a/crypto/bn/bn_shift.c b/crypto/bn/bn_shift.c
index 0883247384..e4da833ea6 100644
--- a/crypto/bn/bn_shift.c
+++ b/crypto/bn/bn_shift.c
@@ -60,7 +60,7 @@
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
-int BN_lshift1(BIGNUM *r, BIGNUM *a)
+int BN_lshift1(BIGNUM *r, const BIGNUM *a)
 	{
 	register BN_ULONG *ap,*rp,t,c;
 	int i;
@@ -92,7 +92,7 @@ int BN_lshift1(BIGNUM *r, BIGNUM *a)
 	return(1);
 	}
 
-int BN_rshift1(BIGNUM *r, BIGNUM *a)
+int BN_rshift1(BIGNUM *r, const BIGNUM *a)
 	{
 	BN_ULONG *ap,*rp,t,c;
 	int i;
@@ -153,7 +153,7 @@ int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
 	return(1);
 	}
 
-int BN_rshift(BIGNUM *r, BIGNUM *a, int n)
+int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
 	{
 	int i,j,nw,lb,rb;
 	BN_ULONG *t,*f;
diff --git a/crypto/bn/bn_sqr.c b/crypto/bn/bn_sqr.c
index 75f4f38392..4789f131a1 100644
--- a/crypto/bn/bn_sqr.c
+++ b/crypto/bn/bn_sqr.c
@@ -62,11 +62,11 @@
 
 /* r must not be a */
 /* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */
-int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx)
+int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
 	{
 	int max,al;
 	int ret = 0;
-	BIGNUM *tmp,*rr;
+	BIGNUM *tmp,*rr,*free_a = NULL;
 
 #ifdef BN_COUNT
 printf("BN_sqr %d * %d\n",a->top,a->top);
@@ -124,8 +124,10 @@ printf("BN_sqr %d * %d\n",a->top,a->top);
 			k=j+j;
 			if (al == j)
 				{
-				if (bn_wexpand(a,k*2) == NULL) goto err;
+				BIGNUM *tmp_bn = free_a;
+				if ((a = free_a = bn_dup_expand(a,k*2)) == NULL) goto err;
 				if (bn_wexpand(tmp,k*2) == NULL) goto err;
+				if (tmp_bn) BN_free(tmp_bn);
 				bn_sqr_recursive(rr->d,a->d,al,tmp->d);
 				}
 			else
@@ -145,6 +147,7 @@ printf("BN_sqr %d * %d\n",a->top,a->top);
 	if (rr != r) BN_copy(r,rr);
 	ret = 1;
  err:
+	if (free_a) BN_free(free_a);
 	BN_CTX_end(ctx);
 	return(ret);
 	}
diff --git a/crypto/bn/bntest.c b/crypto/bn/bntest.c
index 0a97af69c5..11e58f994a 100644
--- a/crypto/bn/bntest.c
+++ b/crypto/bn/bntest.c
@@ -772,6 +772,7 @@ int test_mod_mul(BIO *bp, BN_CTX *ctx)
 		if(!BN_is_zero(b))
 		    {
 		    fprintf(stderr,"Modulo multiply test failed!\n");
+		    ERR_print_errors_fp(stderr);
 		    return 0;
 		    }
 		}
-- 
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