summaryrefslogtreecommitdiff
path: root/crypto/bn/bn_exp.c
diff options
context:
space:
mode:
Diffstat (limited to 'crypto/bn/bn_exp.c')
-rw-r--r--crypto/bn/bn_exp.c69
1 files changed, 37 insertions, 32 deletions
diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index 40115fc..36b7ba6 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -290,8 +290,8 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
bits = BN_num_bits(p);
if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ /* x**0 mod 1, or x**0 mod -1 is still zero. */
+ if (BN_abs_is_word(m, 1)) {
ret = 1;
BN_zero(r);
} else {
@@ -432,8 +432,8 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
}
bits = BN_num_bits(p);
if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ /* x**0 mod 1, or x**0 mod -1 is still zero. */
+ if (BN_abs_is_word(m, 1)) {
ret = 1;
BN_zero(rr);
} else {
@@ -473,17 +473,17 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
ret = 1;
goto err;
}
- if (!BN_to_montgomery(val[0], aa, mont, ctx))
+ if (!bn_to_mont_fixed_top(val[0], aa, mont, ctx))
goto err; /* 1 */
window = BN_window_bits_for_exponent_size(bits);
if (window > 1) {
- if (!BN_mod_mul_montgomery(d, val[0], val[0], mont, ctx))
+ if (!bn_mul_mont_fixed_top(d, val[0], val[0], mont, ctx))
goto err; /* 2 */
j = 1 << (window - 1);
for (i = 1; i < j; i++) {
if (((val[i] = BN_CTX_get(ctx)) == NULL) ||
- !BN_mod_mul_montgomery(val[i], val[i - 1], d, mont, ctx))
+ !bn_mul_mont_fixed_top(val[i], val[i - 1], d, mont, ctx))
goto err;
}
}
@@ -505,19 +505,15 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
for (i = 1; i < j; i++)
r->d[i] = (~m->d[i]) & BN_MASK2;
r->top = j;
- /*
- * Upper words will be zero if the corresponding words of 'm' were
- * 0xfff[...], so decrement r->top accordingly.
- */
- bn_correct_top(r);
+ r->flags |= BN_FLG_FIXED_TOP;
} else
#endif
- if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))
+ if (!bn_to_mont_fixed_top(r, BN_value_one(), mont, ctx))
goto err;
for (;;) {
if (BN_is_bit_set(p, wstart) == 0) {
if (!start) {
- if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
+ if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx))
goto err;
}
if (wstart == 0)
@@ -548,12 +544,12 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
/* add the 'bytes above' */
if (!start)
for (i = 0; i < j; i++) {
- if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
+ if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx))
goto err;
}
/* wvalue will be an odd number < 2^window */
- if (!BN_mod_mul_montgomery(r, r, val[wvalue >> 1], mont, ctx))
+ if (!bn_mul_mont_fixed_top(r, r, val[wvalue >> 1], mont, ctx))
goto err;
/* move the 'window' down further */
@@ -563,6 +559,11 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
if (wstart < 0)
break;
}
+ /*
+ * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery
+ * removes padding [if any] and makes return value suitable for public
+ * API consumer.
+ */
#if defined(SPARC_T4_MONT)
if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) {
j = mont->N.top; /* borrow j */
@@ -681,7 +682,7 @@ static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top,
}
b->top = top;
- bn_correct_top(b);
+ b->flags |= BN_FLG_FIXED_TOP;
return 1;
}
@@ -733,8 +734,8 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
*/
bits = p->top * BN_BITS2;
if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ /* x**0 mod 1, or x**0 mod -1 is still zero. */
+ if (BN_abs_is_word(m, 1)) {
ret = 1;
BN_zero(rr);
} else {
@@ -852,16 +853,16 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
tmp.top = top;
} else
#endif
- if (!BN_to_montgomery(&tmp, BN_value_one(), mont, ctx))
+ if (!bn_to_mont_fixed_top(&tmp, BN_value_one(), mont, ctx))
goto err;
/* prepare a^1 in Montgomery domain */
if (a->neg || BN_ucmp(a, m) >= 0) {
if (!BN_mod(&am, a, m, ctx))
goto err;
- if (!BN_to_montgomery(&am, &am, mont, ctx))
+ if (!bn_to_mont_fixed_top(&am, &am, mont, ctx))
goto err;
- } else if (!BN_to_montgomery(&am, a, mont, ctx))
+ } else if (!bn_to_mont_fixed_top(&am, a, mont, ctx))
goto err;
#if defined(SPARC_T4_MONT)
@@ -1128,14 +1129,14 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
* performance advantage of sqr over mul).
*/
if (window > 1) {
- if (!BN_mod_mul_montgomery(&tmp, &am, &am, mont, ctx))
+ if (!bn_mul_mont_fixed_top(&tmp, &am, &am, mont, ctx))
goto err;
if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2,
window))
goto err;
for (i = 3; i < numPowers; i++) {
/* Calculate a^i = a^(i-1) * a */
- if (!BN_mod_mul_montgomery(&tmp, &am, &tmp, mont, ctx))
+ if (!bn_mul_mont_fixed_top(&tmp, &am, &tmp, mont, ctx))
goto err;
if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i,
window))
@@ -1159,7 +1160,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
/* Scan the window, squaring the result as we go */
for (i = 0; i < window; i++, bits--) {
- if (!BN_mod_mul_montgomery(&tmp, &tmp, &tmp, mont, ctx))
+ if (!bn_mul_mont_fixed_top(&tmp, &tmp, &tmp, mont, ctx))
goto err;
wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
}
@@ -1172,12 +1173,16 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
goto err;
/* Multiply the result into the intermediate result */
- if (!BN_mod_mul_montgomery(&tmp, &tmp, &am, mont, ctx))
+ if (!bn_mul_mont_fixed_top(&tmp, &tmp, &am, mont, ctx))
goto err;
}
}
- /* Convert the final result from montgomery to standard format */
+ /*
+ * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery
+ * removes padding [if any] and makes return value suitable for public
+ * API consumer.
+ */
#if defined(SPARC_T4_MONT)
if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) {
am.d[0] = 1; /* borrow am */
@@ -1247,8 +1252,8 @@ int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
bits = BN_num_bits(p);
if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ /* x**0 mod 1, or x**0 mod -1 is still zero. */
+ if (BN_abs_is_word(m, 1)) {
ret = 1;
BN_zero(rr);
} else {
@@ -1369,9 +1374,9 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
}
bits = BN_num_bits(p);
- if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ if (bits == 0) {
+ /* x**0 mod 1, or x**0 mod -1 is still zero. */
+ if (BN_abs_is_word(m, 1)) {
ret = 1;
BN_zero(r);
} else {
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-01 10:51:43 +0000