[openssl-commits] [openssl] OpenSSL_1_0_2-stable update
Andy Polyakov
appro at openssl.org
Tue Aug 28 17:36:09 UTC 2018
The branch OpenSSL_1_0_2-stable has been updated
via bc251459adc14a1a56d0cbe2d372f3d6ffd20cf8 (commit)
via b6f773b8d6c41e86c107b57dabc637c91884150e (commit)
via f9381fd323303316282331a8cced6e030e809794 (commit)
via 387d170b32ceeac450bfa50b81db9db9179dc880 (commit)
from 19096672b48b3282bb9f11c4adadbcdd545f54a3 (commit)
- Log -----------------------------------------------------------------
commit bc251459adc14a1a56d0cbe2d372f3d6ffd20cf8
Author: Andy Polyakov <appro at openssl.org>
Date: Wed Aug 15 15:46:35 2018 +0200
bn/bn_lib.c: conceal even memmory access pattern in bn2binpad.
(cherry picked from commit 324b95605225410763fe63f7cff36eb46ca54ee9)
Reviewed-by: Paul Dale <paul.dale at oracle.com>
(Merged from https://github.com/openssl/openssl/pull/6942)
commit b6f773b8d6c41e86c107b57dabc637c91884150e
Author: Andy Polyakov <appro at openssl.org>
Date: Mon Aug 13 16:59:08 2018 +0200
bn/bn_blind.c: use Montgomery multiplication when possible.
(cherry picked from commit e02c519cd32a55e6ad39a0cfbeeda775f9115f28)
Resolved conflicts:
crypto/bn/bn_blind.c
Reviewed-by: Paul Dale <paul.dale at oracle.com>
(Merged from https://github.com/openssl/openssl/pull/6942)
commit f9381fd323303316282331a8cced6e030e809794
Author: Andy Polyakov <appro at openssl.org>
Date: Mon Aug 13 20:20:28 2018 +0200
rsa/rsa_eay.c: implement variant of "Smooth CRT-RSA."
In [most common] case of p and q being of same width, it's possible to
replace CRT modulo operations with Montgomery reductions. And those are
even fixed-length Montgomery reductions...
(cherry picked from commit 41bfd5e7c8ac3a0874a94e4d15c006ad5eb48e59)
Resolved conflicts:
crypto/rsa/rsa_eay.c
Reviewed-by: Paul Dale <paul.dale at oracle.com>
(Merged from https://github.com/openssl/openssl/pull/6942)
commit 387d170b32ceeac450bfa50b81db9db9179dc880
Author: Andy Polyakov <appro at openssl.org>
Date: Fri Aug 10 19:31:22 2018 +0200
crypto/bn: add more fixed-top routines.
Add bn_mul_fixed_top, bn_from_mont_fixed_top, bn_mod_sub_fixed_top.
Switch to bn_{mul|sqr}_fixed_top in bn_mul_mont_fixed_top and remove
memset in bn_from_montgomery_word.
(cherry picked from commit fcc4ee09473cac511eca90faa003661c7786e4f9)
Resolved conflicts:
crypto/bn/bn_mod.c
crypto/bn_int.h
Reviewed-by: Paul Dale <paul.dale at oracle.com>
(Merged from https://github.com/openssl/openssl/pull/6942)
-----------------------------------------------------------------------
Summary of changes:
crypto/bn/bn_blind.c | 63 ++++++++++++++++++++++----------
crypto/bn/bn_lib.c | 34 ++++++++++++-----
crypto/bn/bn_mod.c | 67 +++++++++++++++++++++++++++++++++-
crypto/bn/bn_mont.c | 29 ++++++++++-----
crypto/bn/bn_mul.c | 12 +++++-
crypto/bn/bn_sqr.c | 12 +++++-
crypto/bn_int.h | 6 +++
crypto/rsa/rsa_eay.c | 101 ++++++++++++++++++++++++++++++++++++++++++---------
8 files changed, 264 insertions(+), 60 deletions(-)
diff --git a/crypto/bn/bn_blind.c b/crypto/bn/bn_blind.c
index d448daa..40e1bb6 100644
--- a/crypto/bn/bn_blind.c
+++ b/crypto/bn/bn_blind.c
@@ -206,10 +206,15 @@ int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
goto err;
} else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
- if (!BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
- goto err;
- if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx))
- goto err;
+ if (b->m_ctx != NULL) {
+ if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
+ || !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
+ goto err;
+ } else {
+ if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
+ || !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
+ goto err;
+ }
}
ret = 1;
@@ -241,13 +246,13 @@ int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
else if (!BN_BLINDING_update(b, ctx))
return (0);
- if (r != NULL) {
- if (!BN_copy(r, b->Ai))
- ret = 0;
- }
+ if (r != NULL && (BN_copy(r, b->Ai) == NULL))
+ return 0;
- if (!BN_mod_mul(n, n, b->A, b->mod, ctx))
- ret = 0;
+ if (b->m_ctx != NULL)
+ ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
+ else
+ ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
return ret;
}
@@ -264,14 +269,29 @@ int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
bn_check_top(n);
- if (r != NULL)
- ret = BN_mod_mul(n, n, r, b->mod, ctx);
- else {
- if (b->Ai == NULL) {
- BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
- return (0);
+ if (r == NULL && (r = b->Ai) == NULL) {
+ BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
+ return 0;
+ }
+
+ if (b->m_ctx != NULL) {
+ /* ensure that BN_mod_mul_montgomery takes pre-defined path */
+ if (n->dmax >= r->top) {
+ size_t i, rtop = r->top, ntop = n->top;
+ BN_ULONG mask;
+
+ for (i = 0; i < rtop; i++) {
+ mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
+ n->d[i] &= mask;
+ }
+ mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
+ /* always true, if (rtop >= ntop) n->top = r->top; */
+ n->top = (int)(rtop & ~mask) | (ntop & mask);
+ n->flags |= (BN_FLG_FIXED_TOP & ~mask);
}
- ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);
+ ret = BN_mod_mul_montgomery(n, n, r, b->m_ctx, ctx);
+ } else {
+ ret = BN_mod_mul(n, n, r, b->mod, ctx);
}
bn_check_top(n);
@@ -366,14 +386,19 @@ BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
} while (1);
if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
- if (!ret->bn_mod_exp
- (ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
+ if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
goto err;
} else {
if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
goto err;
}
+ if (ret->m_ctx != NULL) {
+ if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
+ || !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
+ goto err;
+ }
+
return ret;
err:
if (b == NULL && ret != NULL) {
diff --git a/crypto/bn/bn_lib.c b/crypto/bn/bn_lib.c
index 03bd8cd..8f1042b 100644
--- a/crypto/bn/bn_lib.c
+++ b/crypto/bn/bn_lib.c
@@ -617,26 +617,40 @@ BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
{
int n;
- size_t i, inc, lasti, j;
+ size_t i, lasti, j, atop, mask;
BN_ULONG l;
+ /*
+ * In case |a| is fixed-top, BN_num_bytes can return bogus length,
+ * but it's assumed that fixed-top inputs ought to be "nominated"
+ * even for padded output, so it works out...
+ */
n = BN_num_bytes(a);
- if (tolen == -1)
+ if (tolen == -1) {
tolen = n;
- else if (tolen < n)
- return -1;
+ } else if (tolen < n) { /* uncommon/unlike case */
+ BIGNUM temp = *a;
- if (n == 0) {
+ bn_correct_top(&temp);
+ n = BN_num_bytes(&temp);
+ if (tolen < n)
+ return -1;
+ }
+
+ /* Swipe through whole available data and don't give away padded zero. */
+ atop = a->dmax * BN_BYTES;
+ if (atop == 0) {
OPENSSL_cleanse(to, tolen);
return tolen;
}
- lasti = n - 1;
- for (i = 0, inc = 1, j = tolen; j > 0;) {
+ lasti = atop - 1;
+ atop = a->top * BN_BYTES;
+ for (i = 0, j = 0, to += tolen; j < (size_t)tolen; j++) {
l = a->d[i / BN_BYTES];
- to[--j] = (unsigned char)(l >> (8 * (i % BN_BYTES)) & (0 - inc));
- inc = (i - lasti) >> (8 * sizeof(i) - 1);
- i += inc; /* stay on top limb */
+ mask = 0 - ((j - atop) >> (8 * sizeof(i) - 1));
+ *--to = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask);
+ i += (i - lasti) >> (8 * sizeof(i) - 1); /* stay on last limb */
}
return tolen;
diff --git a/crypto/bn/bn_mod.c b/crypto/bn/bn_mod.c
index 43da462..255e6e4 100644
--- a/crypto/bn/bn_mod.c
+++ b/crypto/bn/bn_mod.c
@@ -172,7 +172,7 @@ int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
if (mtop > sizeof(storage) / sizeof(storage[0])
&& (tp = OPENSSL_malloc(mtop * sizeof(BN_ULONG))) == NULL)
- return 0;
+ return 0;
ap = a->d != NULL ? a->d : tp;
bp = b->d != NULL ? b->d : tp;
@@ -197,6 +197,7 @@ int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
((volatile BN_ULONG *)tp)[i] = 0;
}
r->top = mtop;
+ r->flags |= BN_FLG_FIXED_TOP;
r->neg = 0;
if (tp != storage)
@@ -225,6 +226,70 @@ int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
}
/*
+ * BN_mod_sub variant that may be used if both a and b are non-negative,
+ * a is less than m, while b is of same bit width as m. It's implemented
+ * as subtraction followed by two conditional additions.
+ *
+ * 0 <= a < m
+ * 0 <= b < 2^w < 2*m
+ *
+ * after subtraction
+ *
+ * -2*m < r = a - b < m
+ *
+ * Thus it takes up to two conditional additions to make |r| positive.
+ */
+int bn_mod_sub_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
+ const BIGNUM *m)
+{
+ size_t i, ai, bi, mtop = m->top;
+ BN_ULONG borrow, carry, ta, tb, mask, *rp;
+ const BN_ULONG *ap, *bp;
+
+ if (bn_wexpand(r, m->top) == NULL)
+ return 0;
+
+ rp = r->d;
+ ap = a->d != NULL ? a->d : rp;
+ bp = b->d != NULL ? b->d : rp;
+
+ for (i = 0, ai = 0, bi = 0, borrow = 0; i < mtop;) {
+ mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1));
+ ta = ap[ai] & mask;
+
+ mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1));
+ tb = bp[bi] & mask;
+ rp[i] = ta - tb - borrow;
+ if (ta != tb)
+ borrow = (ta < tb);
+
+ i++;
+ ai += (i - a->dmax) >> (8 * sizeof(i) - 1);
+ bi += (i - b->dmax) >> (8 * sizeof(i) - 1);
+ }
+ ap = m->d;
+ for (i = 0, mask = 0 - borrow, carry = 0; i < mtop; i++) {
+ ta = ((ap[i] & mask) + carry) & BN_MASK2;
+ carry = (ta < carry);
+ rp[i] = (rp[i] + ta) & BN_MASK2;
+ carry += (rp[i] < ta);
+ }
+ borrow -= carry;
+ for (i = 0, mask = 0 - borrow, carry = 0; i < mtop; i++) {
+ ta = ((ap[i] & mask) + carry) & BN_MASK2;
+ carry = (ta < carry);
+ rp[i] = (rp[i] + ta) & BN_MASK2;
+ carry += (rp[i] < ta);
+ }
+
+ r->top = mtop;
+ r->flags |= BN_FLG_FIXED_TOP;
+ r->neg = 0;
+
+ return 1;
+}
+
+/*
* BN_mod_sub variant that may be used if both a and b are non-negative and
* less than m
*/
diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index d41434a..76eca50 100644
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -164,10 +164,10 @@ int bn_mul_mont_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
bn_check_top(tmp);
if (a == b) {
- if (!BN_sqr(tmp, a, ctx))
+ if (!bn_sqr_fixed_top(tmp, a, ctx))
goto err;
} else {
- if (!BN_mul(tmp, a, b, ctx))
+ if (!bn_mul_fixed_top(tmp, a, b, ctx))
goto err;
}
/* reduce from aRR to aR */
@@ -190,6 +190,7 @@ static int bn_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
BIGNUM *n;
BN_ULONG *ap, *np, *rp, n0, v, carry;
int nl, max, i;
+ unsigned int rtop;
n = &(mont->N);
nl = n->top;
@@ -207,12 +208,10 @@ static int bn_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
rp = r->d;
/* clear the top words of T */
-# if 1
- for (i = r->top; i < max; i++) /* memset? XXX */
- rp[i] = 0;
-# else
- memset(&(rp[r->top]), 0, (max - r->top) * sizeof(BN_ULONG));
-# endif
+ for (rtop = r->top, i = 0; i < max; i++) {
+ v = (BN_ULONG)0 - ((i - rtop) >> (8 * sizeof(rtop) - 1));
+ rp[i] &= v;
+ }
r->top = max;
r->flags |= BN_FLG_FIXED_TOP;
@@ -263,6 +262,18 @@ static int bn_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx)
{
+ int retn;
+
+ retn = bn_from_mont_fixed_top(ret, a, mont, ctx);
+ bn_correct_top(ret);
+ bn_check_top(ret);
+
+ return retn;
+}
+
+int bn_from_mont_fixed_top(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
+ BN_CTX *ctx)
+{
int retn = 0;
#ifdef MONT_WORD
BIGNUM *t;
@@ -270,8 +281,6 @@ int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX_start(ctx);
if ((t = BN_CTX_get(ctx)) && BN_copy(t, a)) {
retn = bn_from_montgomery_word(ret, t, mont);
- bn_correct_top(ret);
- bn_check_top(ret);
}
BN_CTX_end(ctx);
#else /* !MONT_WORD */
diff --git a/crypto/bn/bn_mul.c b/crypto/bn/bn_mul.c
index 6b455a7..f44e5e5 100644
--- a/crypto/bn/bn_mul.c
+++ b/crypto/bn/bn_mul.c
@@ -936,6 +936,16 @@ void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l, int n2,
int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
{
+ int ret = bn_mul_fixed_top(r, a, b, ctx);
+
+ bn_correct_top(r);
+ bn_check_top(r);
+
+ return ret;
+}
+
+int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
+{
int ret = 0;
int top, al, bl;
BIGNUM *rr;
@@ -1042,7 +1052,7 @@ int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
end:
#endif
- bn_correct_top(rr);
+ rr->flags |= BN_FLG_FIXED_TOP;
if (r != rr && BN_copy(r, rr) == NULL)
goto err;
diff --git a/crypto/bn/bn_sqr.c b/crypto/bn/bn_sqr.c
index 5e69297..44bc554 100644
--- a/crypto/bn/bn_sqr.c
+++ b/crypto/bn/bn_sqr.c
@@ -66,6 +66,16 @@
*/
int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
{
+ int ret = bn_sqr_fixed_top(r, a, ctx);
+
+ bn_correct_top(r);
+ bn_check_top(r);
+
+ return ret;
+}
+
+int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
+{
int max, al;
int ret = 0;
BIGNUM *tmp, *rr;
@@ -136,7 +146,7 @@ int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
rr->neg = 0;
rr->top = max;
- bn_correct_top(rr);
+ rr->flags |= BN_FLG_FIXED_TOP;
if (r != rr && BN_copy(r, rr) == NULL)
goto err;
diff --git a/crypto/bn_int.h b/crypto/bn_int.h
index 9c42d6f..a552cc2 100644
--- a/crypto/bn_int.h
+++ b/crypto/bn_int.h
@@ -7,9 +7,15 @@
*/
int bn_mul_mont_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
BN_MONT_CTX *mont, BN_CTX *ctx);
+int bn_from_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
+ BN_CTX *ctx);
int bn_to_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx);
int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
const BIGNUM *m);
+int bn_mod_sub_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
+ const BIGNUM *m);
+int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
+int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx);
int bn_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen);
diff --git a/crypto/rsa/rsa_eay.c b/crypto/rsa/rsa_eay.c
index 7ba24e3..1bb121f 100644
--- a/crypto/rsa/rsa_eay.c
+++ b/crypto/rsa/rsa_eay.c
@@ -224,8 +224,8 @@ static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA,
+ rsa->n, ctx))
goto err;
if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
@@ -432,8 +432,8 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
d = rsa->d;
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA,
+ rsa->n, ctx))
goto err;
if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
@@ -554,8 +554,8 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
d = rsa->d;
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA,
+ rsa->n, ctx))
goto err;
if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
rsa->_method_mod_n))
@@ -660,8 +660,8 @@ static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA,
+ rsa->n, ctx))
goto err;
if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
@@ -708,7 +708,7 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
BIGNUM *r1, *m1, *vrfy;
BIGNUM local_dmp1, local_dmq1, local_c, local_r1;
BIGNUM *dmp1, *dmq1, *c, *pr1;
- int ret = 0;
+ int ret = 0, smooth = 0;
BN_CTX_start(ctx);
r1 = BN_CTX_get(ctx);
@@ -737,20 +737,63 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
}
if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_p, CRYPTO_LOCK_RSA, p, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_p, CRYPTO_LOCK_RSA,
+ p, ctx))
goto err;
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_q, CRYPTO_LOCK_RSA, q, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_q, CRYPTO_LOCK_RSA,
+ q, ctx))
goto err;
+
+ smooth = (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
+ && (BN_num_bits(q) == BN_num_bits(p));
}
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
- if (!BN_MONT_CTX_set_locked
- (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
+ if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA,
+ rsa->n, ctx))
+ goto err;
+
+ if (smooth) {
+ /*
+ * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
+ * accepts values in [0-m*2^w) range. w is m's bit width rounded up
+ * to limb width. So that at the very least if |I| is fully reduced,
+ * i.e. less than p*q, we can count on from-to round to perform
+ * below modulo operations on |I|. Unlike BN_mod it's constant time.
+ */
+ if (/* m1 = I moq q */
+ !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
+ || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
+ /* m1 = m1^dmq1 mod q */
+ || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
+ rsa->_method_mod_q)
+ /* r1 = I mod p */
+ || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
+ || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
+ /* r1 = r1^dmp1 mod p */
+ || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
+ rsa->_method_mod_p)
+ /* r1 = (r1 - m1) mod p */
+ /*
+ * bn_mod_sub_fixed_top is not regular modular subtraction,
+ * it can tolerate subtrahend to be larger than modulus, but
+ * not bit-wise wider. This makes up for uncommon q>p case,
+ * when |m1| can be larger than |rsa->p|.
+ */
+ || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
+
+ /* r0 = r0 * iqmp mod p */
+ || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
+ || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
+ ctx)
+ || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
+ || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
goto err;
+ goto tail;
+ }
+
/* compute I mod q */
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
c = &local_c;
@@ -828,10 +871,18 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
if (!BN_add(r0, r1, m1))
goto err;
+ tail:
if (rsa->e && rsa->n) {
- if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
- rsa->_method_mod_n))
- goto err;
+ if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
+ if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
+ rsa->_method_mod_n))
+ goto err;
+ } else {
+ bn_correct_top(r0);
+ if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
+ rsa->_method_mod_n))
+ goto err;
+ }
/*
* If 'I' was greater than (or equal to) rsa->n, the operation will
* be equivalent to using 'I mod n'. However, the result of the
@@ -840,6 +891,11 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
*/
if (!BN_sub(vrfy, vrfy, I))
goto err;
+ if (BN_is_zero(vrfy)) {
+ bn_correct_top(r0);
+ ret = 1;
+ goto err; /* not actually error */
+ }
if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
goto err;
if (BN_is_negative(vrfy))
@@ -865,6 +921,15 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
goto err;
}
}
+ /*
+ * It's unfortunate that we have to bn_correct_top(r0). What hopefully
+ * saves the day is that correction is highly unlike, and private key
+ * operations are customarily performed on blinded message. Which means
+ * that attacker won't observe correlation with chosen plaintext.
+ * Secondly, remaining code would still handle it in same computational
+ * time and even conceal memory access pattern around corrected top.
+ */
+ bn_correct_top(r0);
ret = 1;
err:
BN_CTX_end(ctx);
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