generic-library/openssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Move zeroing from bn_expand_internal() to bn_expand2() so that it

Browse Source 
happens reliably, even if the BIGNUM is already sufficiently large.

[Note that the bn_expand()/bn_wexpand() macros call bn_expand2() only
if the BIGNUM actually has to grow, so this change does not add any
new overhead as currently bn_expand2() is never called directly.]
This commit is contained in:
Bodo Möller 2002-07-25 12:12:39 +00:00
parent 819a040f44
commit 12593e6f45
1 changed files with 22 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
crypto/bn/bn_lib.c
View File

@ -363,17 +363,6 @@ static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
}
}
/* Now need to zero any data between b->top and b->max */
/* XXX Why? */
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);
@ -397,6 +386,12 @@ BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
{
BIGNUM *r = NULL;
/* This function does not work if
* words <= b->dmax && top < words
* because BN_dup() does not preserve 'dmax'!
* (But bn_dup_expand() is not used anywhere yet.)
*/
if (words > b->dmax)
{
BN_ULONG *a = bn_expand_internal(b, words);
@ -429,12 +424,16 @@ BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
}
/* 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 ensures that 'b' has enough room for a 'words' word number
* and initialises the unused part of b->d with leading zeros.
* 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)
{
BN_ULONG *A;
int i;
if (words > b->dmax)
{
BN_ULONG *a = bn_expand_internal(b, words);
@ -449,6 +448,17 @@ BIGNUM *bn_expand2(BIGNUM *b, int words)
else
b = NULL;
}
/* NB: bn_wexpand() calls this only if the BIGNUM really has to grow */
A = &(b->d[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;
return b;
}