/* The next 2 are needed so we can do a dv->d[0]|=1 later
* since BN_lshift1 will only work once there is a value :-) */
BN_zero(dv);
- bn_wexpand(dv,1);
+ if(bn_wexpand(dv,1) == NULL) goto end;
dv->top=1;
if (!BN_lshift(D,D,nm-nd)) goto end;
*
* <appro@fy.chalmers.se>
*/
+#undef bn_div_words
# define bn_div_words(n0,n1,d0) \
({ asm volatile ( \
"divl %4" \
* Same story here, but it's 128-bit by 64-bit division. Wow!
* <appro@fy.chalmers.se>
*/
+# undef bn_div_words
# define bn_div_words(n0,n1,d0) \
({ asm volatile ( \
"divq %4" \
#endif /* OPENSSL_NO_ASM */
-/* BN_div computes dv := num / divisor, rounding towards zero, and sets up
- * rm such that dv*divisor + rm = num holds.
+/* BN_div computes dv := num / divisor, rounding towards
+ * zero, and sets up rm such that dv*divisor + rm = num holds.
* Thus:
* dv->neg == num->neg ^ divisor->neg (unless the result is zero)
* rm->neg == num->neg (unless the remainder is zero)
BN_ULONG *resp,*wnump;
BN_ULONG d0,d1;
int num_n,div_n;
+ int no_branch=0;
+
+ /* Invalid zero-padding would have particularly bad consequences
+ * in the case of 'num', so don't just rely on bn_check_top() for this one
+ * (bn_check_top() works only for BN_DEBUG builds) */
+ if (num->top > 0 && num->d[num->top - 1] == 0)
+ {
+ BNerr(BN_F_BN_DIV,BN_R_NOT_INITIALIZED);
+ return 0;
+ }
- if (dv)
- bn_check_top(dv);
- if (rm)
- bn_check_top(rm);
bn_check_top(num);
+
+ if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0))
+ {
+ no_branch=1;
+ }
+
+ bn_check_top(dv);
+ bn_check_top(rm);
+ /* bn_check_top(num); */ /* 'num' has been checked already */
bn_check_top(divisor);
if (BN_is_zero(divisor))
return(0);
}
- if (BN_ucmp(num,divisor) < 0)
+ if (!no_branch && BN_ucmp(num,divisor) < 0)
{
if (rm != NULL)
{ if (BN_copy(rm,num) == NULL) return(0); }
if (dv == NULL)
res=BN_CTX_get(ctx);
else res=dv;
- if (sdiv == NULL || res == NULL) goto err;
+ if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL)
+ goto err;
/* First we normalise the numbers */
norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
norm_shift+=BN_BITS2;
if (!(BN_lshift(snum,num,norm_shift))) goto err;
snum->neg=0;
+
+ if (no_branch)
+ {
+ /* Since we don't know whether snum is larger than sdiv,
+ * we pad snum with enough zeroes without changing its
+ * value.
+ */
+ if (snum->top <= sdiv->top+1)
+ {
+ if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err;
+ for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0;
+ snum->top = sdiv->top + 2;
+ }
+ else
+ {
+ if (bn_wexpand(snum, snum->top + 1) == NULL) goto err;
+ snum->d[snum->top] = 0;
+ snum->top ++;
+ }
+ }
+
div_n=sdiv->top;
num_n=snum->top;
loop=num_n-div_n;
/* Setup to 'res' */
res->neg= (num->neg^divisor->neg);
if (!bn_wexpand(res,(loop+1))) goto err;
- res->top=loop;
+ res->top=loop-no_branch;
resp= &(res->d[loop-1]);
/* space for temp */
if (!bn_wexpand(tmp,(div_n+1))) goto err;
- if (BN_ucmp(&wnum,sdiv) >= 0)
+ if (!no_branch)
{
- /* If BN_DEBUG_RAND is defined BN_ucmp changes (via
- * bn_pollute) the const bignum arguments =>
- * clean the values between top and max again */
- bn_clear_top2max(&wnum);
- bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
- *resp=1;
+ if (BN_ucmp(&wnum,sdiv) >= 0)
+ {
+ /* If BN_DEBUG_RAND is defined BN_ucmp changes (via
+ * bn_pollute) the const bignum arguments =>
+ * clean the values between top and max again */
+ bn_clear_top2max(&wnum);
+ bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
+ *resp=1;
+ }
+ else
+ res->top--;
}
- else
- res->top--;
+
/* if res->top == 0 then clear the neg value otherwise decrease
* the resp pointer */
if (res->top == 0)
t2 -= d1;
}
#else /* !BN_LLONG */
- BN_ULONG t2l,t2h,ql,qh;
+ BN_ULONG t2l,t2h;
q=bn_div_words(n0,n1,d0);
#ifdef BN_DEBUG_LEVITTE
t2l = d1 * q;
t2h = BN_UMULT_HIGH(d1,q);
#else
+ {
+ BN_ULONG ql, qh;
t2l=LBITS(d1); t2h=HBITS(d1);
ql =LBITS(q); qh =HBITS(q);
mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
+ }
#endif
for (;;)
rm->neg = neg;
bn_check_top(rm);
}
+ if (no_branch) bn_correct_top(res);
BN_CTX_end(ctx);
return(1);
err:
- if (rm)
- bn_check_top(rm);
+ bn_check_top(rm);
BN_CTX_end(ctx);
return(0);
}
-
#endif
projects / openssl.git / blobdiff