* sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
*/
+#define OPENSSL_FIPSAPI
+
#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"
/* mont->ri will be a multiple of the word size and below code
* is kind of BN_rshift(ret,r,mont->ri) equivalent */
- if (r->top < ri)
+ if (r->top <= ri)
{
ret->top=0;
return(1);
rp=ret->d;
ap=&(r->d[ri]);
- nrp=ap;
- /* This 'if' denotes violation of 2*M<r^(n-1) boundary condition
- * formulated by C.D.Walter in "Montgomery exponentiation needs
- * no final subtractions." Incurred branch can disclose only
- * information about modulus length, which is not really secret. */
- if ((mont->N.d[ri-1]>>(BN_BITS2-2))!=0)
- {
- size_t m1,m2;
-
- v=bn_sub_words(rp,ap,mont->N.d,ri);
- /* this -----------------------^^ works even in al<ri case
- * thanks to zealous zeroing of top of the vector in the
- * beginning. */
-
- /* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
- /* in other words if subtraction result is real, then
- * trick unconditional memcpy below to perform in-place
- * "refresh" instead of actual copy. */
- m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
- m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
- m1|=m2; /* (al!=ri) */
- m1|=(0-(size_t)v); /* (al!=ri || v) */
- m1&=~m2; /* (al!=ri || v) && !al>ri */
- nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
- }
+ {
+ size_t m1,m2;
+
+ v=bn_sub_words(rp,ap,np,ri);
+ /* this ----------------^^ works even in al<ri case
+ * thanks to zealous zeroing of top of the vector in the
+ * beginning. */
+
+ /* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
+ /* in other words if subtraction result is real, then
+ * trick unconditional memcpy below to perform in-place
+ * "refresh" instead of actual copy. */
+ m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
+ m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
+ m1|=m2; /* (al!=ri) */
+ m1|=(0-(size_t)v); /* (al!=ri || v) */
+ m1&=~m2; /* (al!=ri || v) && !al>ri */
+ nrp=(BN_ULONG *)(((PTR_SIZE_INT)rp&~m1)|((PTR_SIZE_INT)ap&m1));
+ }
/* 'i<ri' is chosen to eliminate dependency on input data, even
* though it results in redundant copy in al<ri case. */
}
for (ri+=4; i<ri; i++)
rp[i]=nrp[i], ap[i]=0;
+ bn_correct_top(r);
+ bn_correct_top(ret);
#else
if (bn_wexpand(ret,al) == NULL) return(0);
ret->top=al;
BN_init(&(ctx->RR));
BN_init(&(ctx->N));
BN_init(&(ctx->Ni));
+ ctx->n0[0] = ctx->n0[1] = 0;
ctx->flags=0;
}
BIGNUM tmod;
BN_ULONG buf[2];
+ BN_init(&tmod);
tmod.d=buf;
tmod.dmax=2;
tmod.neg=0;
mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)
+ /* Only certain BN_BITS2<=32 platforms actually make use of
+ * n0[1], and we could use the #else case (with a shorter R
+ * value) for the others. However, currently only the assembler
+ * files do know which is which. */
+
BN_zero(R);
if (!(BN_set_bit(R,2*BN_BITS2))) goto err;