diff --git a/crypto/bn/bn_mont2.c b/crypto/bn/bn_mont2.c
index bd4c01f6cbaf39ec0264b912a4aee0ec14d41f04..16eca4488f408d9ee7e9e4527e861f12f69cb094 100644
--- a/crypto/bn/bn_mont2.c
+++ b/crypto/bn/bn_mont2.c
@@ -21,7 +21,7 @@
 #define BN_mask_word(x, m) ((x->d[0]) & (m))
 
 BN_MONTGOMERY *BN_mont_new()
-{
+	{
 	BN_MONTGOMERY *ret;
 
 	ret=(BN_MONTGOMERY *)malloc(sizeof(BN_MONTGOMERY));
@@ -29,17 +29,17 @@ BN_MONTGOMERY *BN_mont_new()
 	if (ret == NULL) return NULL;
 
 	if ((ret->p = BN_new()) == NULL)
-	{
+		{
 		free(ret);
 		return NULL;
-	}
+		}
 
 	return ret;
-}
+	}
 
 
 void BN_mont_clear_free(BN_MONTGOMERY *mont)
-{
+	{
 	if (mont == NULL) return;
 
 	if (mont->p != NULL) BN_clear_free(mont->p);
@@ -47,10 +47,11 @@ void BN_mont_clear_free(BN_MONTGOMERY *mont)
 	mont->p_num_bytes = 0;
 	mont->R_num_bits = 0;
 	mont->p_inv_b_neg = 0;
-}
+	}
+
 
 int BN_to_mont(BIGNUM *x, BN_MONTGOMERY *mont, BN_CTX *ctx)
-{
+	{
 	assert(x != NULL);
 
 	assert(mont != NULL);
@@ -62,12 +63,12 @@ int BN_to_mont(BIGNUM *x, BN_MONTGOMERY *mont, BN_CTX *ctx)
 	if (!BN_mod(x, x, mont->p, ctx)) return 0;
 
 	return 1;
-}
+	}
 
 
 static BN_ULONG BN_mont_inv(BIGNUM *a, int e, BN_CTX *ctx)
 /* y = a^{-1} (mod 2^e) for an odd number a */
-{
+	{
 	BN_ULONG y, exp, mask;
 	BIGNUM *x, *xy, *x_sh;
 	int i;
@@ -84,27 +85,28 @@ static BN_ULONG BN_mont_inv(BIGNUM *a, int e, BN_CTX *ctx)
 	if((x = BN_dup(a)) == NULL) return 0;
 	if(!BN_mask_bits(x, e)) return 0;
 
-	xy = ctx->bn[ctx->tos]; 
-	x_sh = ctx->bn[ctx->tos + 1]; 
-	ctx->tos += 2;
+	BN_CTX_start(ctx);
+	xy = BN_CTX_get(ctx);
+	x_sh = BN_CTX_get(ctx);
+	if (x_sh == NULL) goto err;
 
 	if (BN_copy(xy, x) == NULL) goto err;
 	if (!BN_lshift1(x_sh, x)) goto err;
 
 
 	for (i = 2; i <= e; i++)
-	{
-		if (exp < BN_mask_word(xy, mask))
 		{
+		if (exp < BN_mask_word(xy, mask))
+			{
 			y = y + exp;
 			if (!BN_add(xy, xy, x_sh)) goto err;
-		}
+			}
 
 		exp <<= 1;
 		if (!BN_lshift1(x_sh, x_sh)) goto err;
 		mask <<= 1;
 		mask++;
-	}
+		}
 
 
 #ifdef TEST
@@ -112,19 +114,19 @@ static BN_ULONG BN_mont_inv(BIGNUM *a, int e, BN_CTX *ctx)
 #endif
 
 	if (x != NULL) BN_clear_free(x);
-	ctx->tos -= 2;
+	BN_CTX_end(ctx);
 	return y;
 
 
 err:
 	if (x != NULL) BN_clear_free(x);
-	ctx->tos -= 2;
+	BN_CTX_end(ctx);
 	return 0;
+	}
 
-}
 
 int BN_mont_set(BIGNUM *p, BN_MONTGOMERY *mont, BN_CTX *ctx)
-{
+	{
 	assert(p != NULL && ctx != NULL);
 	assert(mont != NULL);
 	assert(mont->p != NULL);
@@ -140,22 +142,23 @@ int BN_mont_set(BIGNUM *p, BN_MONTGOMERY *mont, BN_CTX *ctx)
 	mont->p_inv_b_neg = 0 - mont->p_inv_b_neg;
 
 	return 1;
-}
+	}
+
 
 static int BN_cpy_mul_word(BIGNUM *ret, BIGNUM *a, BN_ULONG w)
 /* ret = a * w */
-{
+	{
 	if (BN_copy(ret, a) == NULL) return 0;
 
 	if (!BN_mul_word(ret, w)) return 0;
 
 	return 1;
-}
+	}
 
 
 int BN_mont_red(BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx)
 /* yR^{-1} (mod p) */
-{
+	{
 	int i;
 	BIGNUM *up, *p;
 	BN_ULONG u;
@@ -169,12 +172,13 @@ int BN_mont_red(BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx)
 	if (BN_is_zero(y)) return 1;
 
 	p = mont->p;
-	up = ctx->bn[ctx->tos]; 
-	ctx->tos += 1;
 
+	BN_CTX_start(ctx);
+	up = BN_CTX_get(ctx);
+	if (up == NULL) goto err;
 
 	for (i = 0; i < mont->p_num_bytes; i++)
-	{
+		{
 		u = (y->d[0]) * mont->p_inv_b_neg;			/* u = y_0 * p' */
 
 		if (!BN_cpy_mul_word(up, p, u)) goto err;	/* up = u * p */
@@ -184,28 +188,27 @@ int BN_mont_red(BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx)
 		if (y->d[0]) goto err;
 #endif
 		if (!BN_rshift(y, y, BN_BITS2)) goto err;	/* y = (y + up)/b */
-	}
+		}
 
 
-	if (BN_cmp(y, mont->p) >= 0) 
-	{
+	if (BN_cmp(y, mont->p) >= 0)
+		{
 		if (!BN_sub(y, y, mont->p)) goto err;
-	}
+		}
 
-	ctx->tos -= 1;
+	BN_CTX_end(ctx);
 	return 1;
 
 err:
-	ctx->tos -= 1;
+	BN_CTX_end(ctx);
 	return 0;
-
-}
+	}
 
 
 int BN_mont_mod_mul(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx)
 /* r = x * y mod p */
 /* r != x && r! = y !!! */
-{
+	{
 	BIGNUM *xiy, *up;
 	BN_ULONG u;
 	int i;
@@ -220,21 +223,22 @@ int BN_mont_mod_mul(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX
 	assert(!y->neg);
 
 	if (BN_is_zero(x) || BN_is_zero(y))
-	{
+		{
 		if (!BN_zero(r)) return 0;
 		return 1;
-	}
+		}
 
 
 
-	xiy = ctx->bn[ctx->tos]; 
-	up = ctx->bn[ctx->tos + 1]; 
-	ctx->tos += 2;
+	BN_CTX_start(ctx);
+	xiy = BN_CTX_get(ctx);
+	up = BN_CTX_get(ctx);
+	if (up == NULL) goto err;
 
 	if (!BN_zero(r)) goto err;
 
 	for (i = 0; i < x->top; i++)
-	{
+		{
 		u = (r->d[0] + x->d[i] * y->d[0]) * mont->p_inv_b_neg;
 
 		if (!BN_cpy_mul_word(xiy, y, x->d[i])) goto err;
@@ -246,11 +250,11 @@ int BN_mont_mod_mul(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX
 #ifdef TEST
 		if (r->d[0]) goto err;
 #endif
-		if (!BN_rshift(r, r, BN_BITS2)) goto err; 
-	}
+		if (!BN_rshift(r, r, BN_BITS2)) goto err;
+		}
 
 	for (i = x->top; i < mont->p_num_bytes; i++)
-	{
+		{
 		u = (r->d[0]) * mont->p_inv_b_neg;
 
 		if (!BN_cpy_mul_word(up, mont->p, u)) goto err;
@@ -260,20 +264,20 @@ int BN_mont_mod_mul(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX
 #ifdef TEST
 		if (r->d[0]) goto err;
 #endif
-		if (!BN_rshift(r, r, BN_BITS2)) goto err; 
-	}
+		if (!BN_rshift(r, r, BN_BITS2)) goto err;
+		}
 
 
-	if (BN_cmp(r, mont->p) >= 0) 
-	{
+	if (BN_cmp(r, mont->p) >= 0)
+		{
 		if (!BN_sub(r, r, mont->p)) goto err;
-	}
+		}
 
 
-	ctx->tos -= 2;
+	BN_CTX_end(ctx);
 	return 1;
 
 err:
-	ctx->tos -= 2;
+	BN_CTX_end(ctx);
 	return 0;
-}
+	}