Commit 09338871 authored by Andy Polyakov's avatar Andy Polyakov
Browse files

bn_exp.c: fix corner case in new constant-time code. 

Submitted by: Emilia Kasper
parent b08259cd

crypto/bn/bn_exp.c

+5 −0
Original line number Diff line number Diff line
@@ -693,6 +693,11 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p, 


	BN_ULONG *np=mont->N.d, *n0=mont->n0;



	/* BN_to_montgomery can contaminate words above .top

	 * [in BN_DEBUG[_DEBUG] build]... */

	for (i=am.top; i<top; i++)	am.d[i]=0;

	for (i=tmp.top; i<top; i++)	tmp.d[i]=0;



	bn_scatter5(tmp.d,top,powerbuf,0);

	bn_scatter5(am.d,am.top,powerbuf,1);

	bn_mul_mont(tmp.d,am.d,am.d,np,n0,top);