* [including the GNU Public Licence.]
*/
+#define OPENSSL_FIPSAPI
+
#include <stdio.h>
#include <openssl/bn.h>
#include "cryptlib.h"
/* 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)
int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
BN_CTX *ctx)
{
- int norm_shift,i,j,loop;
+ int norm_shift,i,loop;
BIGNUM *tmp,wnum,*snum,*sdiv,*res;
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;
+ }
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;
- tmp->neg=0;
+ 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;
-
/* Lets setup a 'window' into snum
* This is the part that corresponds to the current
* 'area' being divided */
- BN_init(&wnum);
- wnum.d= &(snum->d[loop]);
- wnum.top= div_n;
- wnum.dmax= snum->dmax+1; /* a bit of a lie */
+ wnum.neg = 0;
+ wnum.d = &(snum->d[loop]);
+ wnum.top = div_n;
+ /* only needed when BN_ucmp messes up the values between top and max */
+ wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */
/* Get the top 2 words of sdiv */
- /* i=sdiv->top; */
+ /* div_n=sdiv->top; */
d0=sdiv->d[div_n-1];
d1=(div_n == 1)?0:sdiv->d[div_n-2];
/* 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_usub(&wnum,&wnum,sdiv)) goto err;
- *resp=1;
- res->d[res->top-1]=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)
res->neg = 0;
- resp--;
+ else
+ resp--;
- for (i=0; i<loop-1; i++)
+ for (i=0; i<loop-1; i++, wnump--, resp--)
{
BN_ULONG q,l0;
+ /* the first part of the loop uses the top two words of
+ * snum and sdiv to calculate a BN_ULONG q such that
+ * | wnum - sdiv * q | < sdiv */
#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
q=bn_div_3_words(wnump,d1,d0);
q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
#else
q=bn_div_words(n0,n1,d0);
+#ifdef BN_DEBUG_LEVITTE
+ fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
+X) -> 0x%08X\n",
+ n0, n1, d0, q);
+#endif
#endif
#ifndef REMAINDER_IS_ALREADY_CALCULATED
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
+ fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
+X) -> 0x%08X\n",
+ n0, n1, d0, q);
+#endif
#ifndef REMAINDER_IS_ALREADY_CALCULATED
rem=(n1-q*d0)&BN_MASK2;
#endif
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 (;;)
#endif /* !BN_DIV3W */
l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
- wnum.d--; wnum.top++;
tmp->d[div_n]=l0;
- for (j=div_n+1; j>0; j--)
- if (tmp->d[j-1]) break;
- tmp->top=j;
-
- j=wnum.top;
- if (!BN_sub(&wnum,&wnum,tmp)) goto err;
-
- snum->top=snum->top+wnum.top-j;
-
- if (wnum.neg)
+ wnum.d--;
+ /* ingore top values of the bignums just sub the two
+ * BN_ULONG arrays with bn_sub_words */
+ if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1))
{
+ /* Note: As we have considered only the leading
+ * two BN_ULONGs in the calculation of q, sdiv * q
+ * might be greater than wnum (but then (q-1) * sdiv
+ * is less or equal than wnum)
+ */
q--;
- j=wnum.top;
- if (!BN_add(&wnum,&wnum,sdiv)) goto err;
- snum->top+=wnum.top-j;
+ if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
+ /* we can't have an overflow here (assuming
+ * that q != 0, but if q == 0 then tmp is
+ * zero anyway) */
+ (*wnump)++;
}
- *(resp--)=q;
- wnump--;
+ /* store part of the result */
+ *resp = q;
}
+ bn_correct_top(snum);
if (rm != NULL)
{
/* Keep a copy of the neg flag in num because if rm==num
BN_rshift(rm,snum,norm_shift);
if (!BN_is_zero(rm))
rm->neg = neg;
+ bn_check_top(rm);
}
+ if (no_branch) bn_correct_top(res);
BN_CTX_end(ctx);
return(1);
err:
+ bn_check_top(rm);
BN_CTX_end(ctx);
return(0);
}
-
#endif
projects / openssl.git / blobdiff