Commit 73c2522c authored by Bodo Möller's avatar Bodo Möller
Browse files

Handle special cases correctly in exponentation functions. 

test_bn still fails in the BN_sqrt test because
small primes appear to turn into zero for no
obvious reason, leading to "div by zero" errors.
parent 6b5d39e8

crypto/bn/bn_exp.c

+16 −15
Original line number Diff line number Diff line
@@ -240,11 +240,6 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, 
		ret = BN_one(r);

		return ret;

		}

	if (BN_is_zero(a))

		{

		ret = BN_zero(r);

		return ret;

		}



	BN_CTX_start(ctx);

	if ((aa = BN_CTX_get(ctx)) == NULL) goto err;
@@ -256,6 +251,11 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, 
	ts=1;



	if (!BN_nnmod(&(val[0]),a,m,ctx)) goto err;		/* 1 */

	if (BN_is_zero(&(val[0])))

		{

		ret = BN_zero(r);

		goto err;

		}



	window = BN_window_bits_for_exponent_size(bits);

	if (window > 1)
@@ -365,11 +365,7 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p, 
		ret = BN_one(rr);

		return ret;

		}

	if (BN_is_zero(a))

		{

		ret = BN_zero(rr);

		return ret;

		}



	BN_CTX_start(ctx);

	d = BN_CTX_get(ctx);

	r = BN_CTX_get(ctx);
@@ -396,6 +392,11 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p, 
		}

	else

		aa=a;

	if (BN_is_zero(aa))

		{

		ret = BN_zero(rr);

		goto err;

		}

	if (!BN_to_montgomery(&(val[0]),aa,mont,ctx)) goto err; /* 1 */



	window = BN_window_bits_for_exponent_size(bits);
@@ -632,11 +633,6 @@ int BN_mod_exp_simple(BIGNUM *r, 
		ret = BN_one(r);

		return ret;

		}

	if (BN_is_zero(a))

		{

		ret = BN_one(r);

		return ret;

		}



	BN_CTX_start(ctx);

	if ((d = BN_CTX_get(ctx)) == NULL) goto err;
@@ -644,6 +640,11 @@ int BN_mod_exp_simple(BIGNUM *r, 
	BN_init(&(val[0]));

	ts=1;

	if (!BN_nnmod(&(val[0]),a,m,ctx)) goto err;		/* 1 */

	if (BN_is_zero(&(val[0])))

		{

		ret = BN_one(r);

		return ret;

		}



	window = BN_window_bits_for_exponent_size(bits);

	if (window > 1)

crypto/bn/bn_exp2.c

+13 −7
Original line number Diff line number Diff line
@@ -144,11 +144,6 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, 
		ret = BN_one(rr);

		return ret;

		}

	if (BN_is_zero(a1) || BN_is_zero(a2))

		{

		ret = BN_zero(rr);

		return ret;

		}

	

	bits=(bits1 > bits2)?bits1:bits2;
@@ -173,7 +168,7 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, 
	 */

	BN_init(&val1[0]);

	ts1=1;

	if (BN_ucmp(a1,m) >= 0)

	if (a1->neg || BN_ucmp(a1,m) >= 0)

		{

		if (!BN_mod(&(val1[0]),a1,m,ctx))

			goto err;
@@ -181,6 +176,12 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, 
		}

	else

		a_mod_m = a1;

	if (BN_is_zero(&(val1[0])))

		{

		ret = BN_zero(rr);

		goto err;

		}



	if (!BN_to_montgomery(&(val1[0]),a_mod_m,mont,ctx)) goto err;

	if (window1 > 1)

		{
@@ -202,7 +203,7 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, 
	 */

	BN_init(&val2[0]);

	ts2=1;

	if (BN_ucmp(a2,m) >= 0)

	if (a2->neg || BN_ucmp(a2,m) >= 0)

		{

		if (!BN_mod(&(val2[0]),a2,m,ctx))

			goto err;
@@ -210,6 +211,11 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, 
		}

	else

		a_mod_m = a2;

	if (BN_is_zero(&(val2[0])))

		{

		ret = BN_zero(rr);

		goto err;

		}

	if (!BN_to_montgomery(&(val2[0]),a_mod_m,mont,ctx)) goto err;

	if (window2 > 1)

		{