[openssl-commits] [openssl] master update
Andy Polyakov
appro at openssl.org
Wed May 9 11:30:58 UTC 2018
The branch master has been updated
via 60845a0aa4e54f2973bc178daa5ed475ea4e148d (commit)
via 0dae8bafceabc8966383aa1f11ee8622f7dbde2f (commit)
via a7b0b69c6e9fa172aeb1ac0ede5ef306315dd80c (commit)
via fe2d3975880e6a89702f18ec58881307bf862542 (commit)
from 06e0950d20d3110849dea28eb78cac4127618b48 (commit)
- Log -----------------------------------------------------------------
commit 60845a0aa4e54f2973bc178daa5ed475ea4e148d
Author: Nicola Tuveri <nic.tuv at gmail.com>
Date: Wed Apr 25 15:27:59 2018 +0300
Add CHANGES entry for PR#6009
Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Andy Polyakov <appro at openssl.org>
Reviewed-by: Rich Salz <rsalz at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6070)
commit 0dae8bafceabc8966383aa1f11ee8622f7dbde2f
Author: Billy Brumley <bbrumley at gmail.com>
Date: Tue Apr 24 16:03:42 2018 +0300
Add blinding in BN_GF2m_mod_inv for binary field inversions
Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Andy Polyakov <appro at openssl.org>
Reviewed-by: Rich Salz <rsalz at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6070)
commit a7b0b69c6e9fa172aeb1ac0ede5ef306315dd80c
Author: Billy Brumley <bbrumley at gmail.com>
Date: Tue Apr 24 16:01:53 2018 +0300
ECC: unify generic ec2 and ecp scalar multiplication, deprecate ec2_mult.c
Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Andy Polyakov <appro at openssl.org>
Reviewed-by: Rich Salz <rsalz at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6070)
commit fe2d3975880e6a89702f18ec58881307bf862542
Author: Billy Brumley <bbrumley at gmail.com>
Date: Tue Apr 24 16:00:08 2018 +0300
ECDSA: remove nonce padding (delegated to EC_POINT_mul)
* EC_POINT_mul is now responsible for constant time point multiplication
(for single fixed or variable point multiplication, when the scalar is
in the range [0,group_order), so we need to strip the nonce padding
from ECDSA.
* Entry added to CHANGES
* Updated EC_POINT_mul documentation
- Integrate existing EC_POINT_mul and EC_POINTs_mul entries in the
manpage to reflect the shift in constant-time expectations when
performing a single fixed or variable point multiplication;
- Add documentation to ec_method_st to reflect the updated "contract"
between callers and implementations of ec_method_st.mul.
Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Andy Polyakov <appro at openssl.org>
Reviewed-by: Rich Salz <rsalz at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6070)
-----------------------------------------------------------------------
Summary of changes:
CHANGES | 20 +++
crypto/bn/bn_gf2m.c | 132 +++++----------
crypto/ec/build.info | 2 +-
crypto/ec/ec2_mult.c | 404 ----------------------------------------------
crypto/ec/ec2_smpl.c | 11 +-
crypto/ec/ec_lcl.h | 25 ++-
crypto/ec/ec_mult.c | 4 +-
crypto/ec/ecdsa_ossl.c | 17 --
doc/man3/EC_POINT_add.pod | 8 +-
9 files changed, 90 insertions(+), 533 deletions(-)
delete mode 100644 crypto/ec/ec2_mult.c
diff --git a/CHANGES b/CHANGES
index a13183f..e8b92cc 100644
--- a/CHANGES
+++ b/CHANGES
@@ -9,6 +9,26 @@
Changes between 1.1.0h and 1.1.1 [xx XXX xxxx]
+ *) Apply blinding to binary field modular inversion and remove patent
+ pending (OPENSSL_SUN_GF2M_DIV) BN_GF2m_mod_div implementation.
+ [Billy Bob Brumley]
+
+ *) Deprecate ec2_mult.c and unify scalar multiplication code paths for
+ binary and prime elliptic curves.
+ [Billy Bob Brumley]
+
+ *) Remove ECDSA nonce padding: EC_POINT_mul is now responsible for
+ constant time fixed point multiplication.
+ [Billy Bob Brumley]
+
+ *) Revise elliptic curve scalar multiplication with timing attack
+ defenses: ec_wNAF_mul redirects to a constant time implementation
+ when computing fixed point and variable point multiplication (which
+ in OpenSSL are mostly used with secret scalars in keygen, sign,
+ ECDH derive operations).
+ [Billy Bob Brumley, Nicola Tuveri, Cesar Pereida García,
+ Sohaib ul Hassan]
+
*) Updated CONTRIBUTING
[Rich Salz]
diff --git a/crypto/bn/bn_gf2m.c b/crypto/bn/bn_gf2m.c
index 16868f7..287adf3 100644
--- a/crypto/bn/bn_gf2m.c
+++ b/crypto/bn/bn_gf2m.c
@@ -547,7 +547,8 @@ int BN_GF2m_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
* Hernandez, J.L., and Menezes, A. "Software Implementation of Elliptic
* Curve Cryptography Over Binary Fields".
*/
-int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
+static int BN_GF2m_mod_inv_vartime(BIGNUM *r, const BIGNUM *a,
+ const BIGNUM *p, BN_CTX *ctx)
{
BIGNUM *b, *c = NULL, *u = NULL, *v = NULL, *tmp;
int ret = 0;
@@ -713,6 +714,46 @@ int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
return ret;
}
+/*-
+ * Wrapper for BN_GF2m_mod_inv_vartime that blinds the input before calling.
+ * This is not constant time.
+ * But it does eliminate first order deduction on the input.
+ */
+int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
+{
+ BIGNUM *b = NULL;
+ int ret = 0;
+
+ BN_CTX_start(ctx);
+ if ((b = BN_CTX_get(ctx)) == NULL)
+ goto err;
+
+ /* generate blinding value */
+ do {
+ if (!BN_priv_rand(b, BN_num_bits(p) - 1,
+ BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
+ goto err;
+ } while (BN_is_zero(b));
+
+ /* r := a * b */
+ if (!BN_GF2m_mod_mul(r, a, b, p, ctx))
+ goto err;
+
+ /* r := 1/(a * b) */
+ if (!BN_GF2m_mod_inv_vartime(r, r, p, ctx))
+ goto err;
+
+ /* r := b/(a * b) = 1/a */
+ if (!BN_GF2m_mod_mul(r, r, b, p, ctx))
+ goto err;
+
+ ret = 1;
+
+ err:
+ BN_CTX_end(ctx);
+ return ret;
+}
+
/*
* Invert xx, reduce modulo p, and store the result in r. r could be xx.
* This function calls down to the BN_GF2m_mod_inv implementation; this
@@ -740,7 +781,6 @@ int BN_GF2m_mod_inv_arr(BIGNUM *r, const BIGNUM *xx, const int p[],
return ret;
}
-# ifndef OPENSSL_SUN_GF2M_DIV
/*
* Divide y by x, reduce modulo p, and store the result in r. r could be x
* or y, x could equal y.
@@ -771,94 +811,6 @@ int BN_GF2m_mod_div(BIGNUM *r, const BIGNUM *y, const BIGNUM *x,
BN_CTX_end(ctx);
return ret;
}
-# else
-/*
- * Divide y by x, reduce modulo p, and store the result in r. r could be x
- * or y, x could equal y. Uses algorithm Modular_Division_GF(2^m) from
- * Chang-Shantz, S. "From Euclid's GCD to Montgomery Multiplication to the
- * Great Divide".
- */
-int BN_GF2m_mod_div(BIGNUM *r, const BIGNUM *y, const BIGNUM *x,
- const BIGNUM *p, BN_CTX *ctx)
-{
- BIGNUM *a, *b, *u, *v;
- int ret = 0;
-
- bn_check_top(y);
- bn_check_top(x);
- bn_check_top(p);
-
- BN_CTX_start(ctx);
-
- a = BN_CTX_get(ctx);
- b = BN_CTX_get(ctx);
- u = BN_CTX_get(ctx);
- v = BN_CTX_get(ctx);
- if (v == NULL)
- goto err;
-
- /* reduce x and y mod p */
- if (!BN_GF2m_mod(u, y, p))
- goto err;
- if (!BN_GF2m_mod(a, x, p))
- goto err;
- if (!BN_copy(b, p))
- goto err;
-
- while (!BN_is_odd(a)) {
- if (!BN_rshift1(a, a))
- goto err;
- if (BN_is_odd(u))
- if (!BN_GF2m_add(u, u, p))
- goto err;
- if (!BN_rshift1(u, u))
- goto err;
- }
-
- do {
- if (BN_GF2m_cmp(b, a) > 0) {
- if (!BN_GF2m_add(b, b, a))
- goto err;
- if (!BN_GF2m_add(v, v, u))
- goto err;
- do {
- if (!BN_rshift1(b, b))
- goto err;
- if (BN_is_odd(v))
- if (!BN_GF2m_add(v, v, p))
- goto err;
- if (!BN_rshift1(v, v))
- goto err;
- } while (!BN_is_odd(b));
- } else if (BN_abs_is_word(a, 1))
- break;
- else {
- if (!BN_GF2m_add(a, a, b))
- goto err;
- if (!BN_GF2m_add(u, u, v))
- goto err;
- do {
- if (!BN_rshift1(a, a))
- goto err;
- if (BN_is_odd(u))
- if (!BN_GF2m_add(u, u, p))
- goto err;
- if (!BN_rshift1(u, u))
- goto err;
- } while (!BN_is_odd(a));
- }
- } while (1);
-
- if (!BN_copy(r, u))
- goto err;
- bn_check_top(r);
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- return ret;
-}
-# endif
/*
* Divide yy by xx, reduce modulo p, and store the result in r. r could be xx
diff --git a/crypto/ec/build.info b/crypto/ec/build.info
index 1e7814f..db506c5 100644
--- a/crypto/ec/build.info
+++ b/crypto/ec/build.info
@@ -2,7 +2,7 @@ LIBS=../../libcrypto
SOURCE[../../libcrypto]=\
ec_lib.c ecp_smpl.c ecp_mont.c ecp_nist.c ec_cvt.c ec_mult.c \
ec_err.c ec_curve.c ec_check.c ec_print.c ec_asn1.c ec_key.c \
- ec2_smpl.c ec2_mult.c ec_ameth.c ec_pmeth.c eck_prn.c \
+ ec2_smpl.c ec_ameth.c ec_pmeth.c eck_prn.c \
ecp_nistp224.c ecp_nistp256.c ecp_nistp521.c ecp_nistputil.c \
ecp_oct.c ec2_oct.c ec_oct.c ec_kmeth.c ecdh_ossl.c ecdh_kdf.c \
ecdsa_ossl.c ecdsa_sign.c ecdsa_vrf.c curve25519.c ecx_meth.c \
diff --git a/crypto/ec/ec2_mult.c b/crypto/ec/ec2_mult.c
deleted file mode 100644
index 891e810..0000000
--- a/crypto/ec/ec2_mult.c
+++ /dev/null
@@ -1,404 +0,0 @@
-/*
- * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
- * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
- *
- * Licensed under the OpenSSL license (the "License"). You may not use
- * this file except in compliance with the License. You can obtain a copy
- * in the file LICENSE in the source distribution or at
- * https://www.openssl.org/source/license.html
- */
-
-#include <openssl/err.h>
-
-#include "internal/bn_int.h"
-#include "ec_lcl.h"
-
-#ifndef OPENSSL_NO_EC2M
-
-/*-
- * Compute the x-coordinate x/z for the point 2*(x/z) in Montgomery projective
- * coordinates.
- * Uses algorithm Mdouble in appendix of
- * Lopez, J. and Dahab, R. "Fast multiplication on elliptic curves over
- * GF(2^m) without precomputation" (CHES '99, LNCS 1717).
- * modified to not require precomputation of c=b^{2^{m-1}}.
- */
-static int gf2m_Mdouble(const EC_GROUP *group, BIGNUM *x, BIGNUM *z,
- BN_CTX *ctx)
-{
- BIGNUM *t1;
- int ret = 0;
-
- /* Since Mdouble is static we can guarantee that ctx != NULL. */
- BN_CTX_start(ctx);
- t1 = BN_CTX_get(ctx);
- if (t1 == NULL)
- goto err;
-
- if (!group->meth->field_sqr(group, x, x, ctx))
- goto err;
- if (!group->meth->field_sqr(group, t1, z, ctx))
- goto err;
- if (!group->meth->field_mul(group, z, x, t1, ctx))
- goto err;
- if (!group->meth->field_sqr(group, x, x, ctx))
- goto err;
- if (!group->meth->field_sqr(group, t1, t1, ctx))
- goto err;
- if (!group->meth->field_mul(group, t1, group->b, t1, ctx))
- goto err;
- if (!BN_GF2m_add(x, x, t1))
- goto err;
-
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- return ret;
-}
-
-/*-
- * Compute the x-coordinate x1/z1 for the point (x1/z1)+(x2/x2) in Montgomery
- * projective coordinates.
- * Uses algorithm Madd in appendix of
- * Lopez, J. and Dahab, R. "Fast multiplication on elliptic curves over
- * GF(2^m) without precomputation" (CHES '99, LNCS 1717).
- */
-static int gf2m_Madd(const EC_GROUP *group, const BIGNUM *x, BIGNUM *x1,
- BIGNUM *z1, const BIGNUM *x2, const BIGNUM *z2,
- BN_CTX *ctx)
-{
- BIGNUM *t1, *t2;
- int ret = 0;
-
- /* Since Madd is static we can guarantee that ctx != NULL. */
- BN_CTX_start(ctx);
- t1 = BN_CTX_get(ctx);
- t2 = BN_CTX_get(ctx);
- if (t2 == NULL)
- goto err;
-
- if (!BN_copy(t1, x))
- goto err;
- if (!group->meth->field_mul(group, x1, x1, z2, ctx))
- goto err;
- if (!group->meth->field_mul(group, z1, z1, x2, ctx))
- goto err;
- if (!group->meth->field_mul(group, t2, x1, z1, ctx))
- goto err;
- if (!BN_GF2m_add(z1, z1, x1))
- goto err;
- if (!group->meth->field_sqr(group, z1, z1, ctx))
- goto err;
- if (!group->meth->field_mul(group, x1, z1, t1, ctx))
- goto err;
- if (!BN_GF2m_add(x1, x1, t2))
- goto err;
-
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- return ret;
-}
-
-/*-
- * Compute the x, y affine coordinates from the point (x1, z1) (x2, z2)
- * using Montgomery point multiplication algorithm Mxy() in appendix of
- * Lopez, J. and Dahab, R. "Fast multiplication on elliptic curves over
- * GF(2^m) without precomputation" (CHES '99, LNCS 1717).
- * Returns:
- * 0 on error
- * 1 if return value should be the point at infinity
- * 2 otherwise
- */
-static int gf2m_Mxy(const EC_GROUP *group, const BIGNUM *x, const BIGNUM *y,
- BIGNUM *x1, BIGNUM *z1, BIGNUM *x2, BIGNUM *z2,
- BN_CTX *ctx)
-{
- BIGNUM *t3, *t4, *t5;
- int ret = 0;
-
- if (BN_is_zero(z1)) {
- BN_zero(x2);
- BN_zero(z2);
- return 1;
- }
-
- if (BN_is_zero(z2)) {
- if (!BN_copy(x2, x))
- return 0;
- if (!BN_GF2m_add(z2, x, y))
- return 0;
- return 2;
- }
-
- /* Since Mxy is static we can guarantee that ctx != NULL. */
- BN_CTX_start(ctx);
- t3 = BN_CTX_get(ctx);
- t4 = BN_CTX_get(ctx);
- t5 = BN_CTX_get(ctx);
- if (t5 == NULL)
- goto err;
-
- if (!BN_one(t5))
- goto err;
-
- if (!group->meth->field_mul(group, t3, z1, z2, ctx))
- goto err;
-
- if (!group->meth->field_mul(group, z1, z1, x, ctx))
- goto err;
- if (!BN_GF2m_add(z1, z1, x1))
- goto err;
- if (!group->meth->field_mul(group, z2, z2, x, ctx))
- goto err;
- if (!group->meth->field_mul(group, x1, z2, x1, ctx))
- goto err;
- if (!BN_GF2m_add(z2, z2, x2))
- goto err;
-
- if (!group->meth->field_mul(group, z2, z2, z1, ctx))
- goto err;
- if (!group->meth->field_sqr(group, t4, x, ctx))
- goto err;
- if (!BN_GF2m_add(t4, t4, y))
- goto err;
- if (!group->meth->field_mul(group, t4, t4, t3, ctx))
- goto err;
- if (!BN_GF2m_add(t4, t4, z2))
- goto err;
-
- if (!group->meth->field_mul(group, t3, t3, x, ctx))
- goto err;
- if (!group->meth->field_div(group, t3, t5, t3, ctx))
- goto err;
- if (!group->meth->field_mul(group, t4, t3, t4, ctx))
- goto err;
- if (!group->meth->field_mul(group, x2, x1, t3, ctx))
- goto err;
- if (!BN_GF2m_add(z2, x2, x))
- goto err;
-
- if (!group->meth->field_mul(group, z2, z2, t4, ctx))
- goto err;
- if (!BN_GF2m_add(z2, z2, y))
- goto err;
-
- ret = 2;
-
- err:
- BN_CTX_end(ctx);
- return ret;
-}
-
-/*-
- * Computes scalar*point and stores the result in r.
- * point can not equal r.
- * Uses a modified algorithm 2P of
- * Lopez, J. and Dahab, R. "Fast multiplication on elliptic curves over
- * GF(2^m) without precomputation" (CHES '99, LNCS 1717).
- *
- * To protect against side-channel attack the function uses constant time swap,
- * avoiding conditional branches.
- */
-static int ec_GF2m_montgomery_point_multiply(const EC_GROUP *group,
- EC_POINT *r,
- const BIGNUM *scalar,
- const EC_POINT *point,
- BN_CTX *ctx)
-{
- BIGNUM *x1, *x2, *z1, *z2;
- int ret = 0, i, group_top;
- BN_ULONG mask, word;
-
- if (r == point) {
- ECerr(EC_F_EC_GF2M_MONTGOMERY_POINT_MULTIPLY, EC_R_INVALID_ARGUMENT);
- return 0;
- }
-
- /* if result should be point at infinity */
- if ((scalar == NULL) || BN_is_zero(scalar) || (point == NULL) ||
- EC_POINT_is_at_infinity(group, point)) {
- return EC_POINT_set_to_infinity(group, r);
- }
-
- /* only support affine coordinates */
- if (!point->Z_is_one)
- return 0;
-
- /*
- * Since point_multiply is static we can guarantee that ctx != NULL.
- */
- BN_CTX_start(ctx);
- x1 = BN_CTX_get(ctx);
- z1 = BN_CTX_get(ctx);
- if (z1 == NULL)
- goto err;
-
- x2 = r->X;
- z2 = r->Y;
-
- group_top = bn_get_top(group->field);
- if (bn_wexpand(x1, group_top) == NULL
- || bn_wexpand(z1, group_top) == NULL
- || bn_wexpand(x2, group_top) == NULL
- || bn_wexpand(z2, group_top) == NULL)
- goto err;
-
- if (!BN_GF2m_mod_arr(x1, point->X, group->poly))
- goto err; /* x1 = x */
- if (!BN_one(z1))
- goto err; /* z1 = 1 */
- if (!group->meth->field_sqr(group, z2, x1, ctx))
- goto err; /* z2 = x1^2 = x^2 */
- if (!group->meth->field_sqr(group, x2, z2, ctx))
- goto err;
- if (!BN_GF2m_add(x2, x2, group->b))
- goto err; /* x2 = x^4 + b */
-
- /* find top most bit and go one past it */
- i = bn_get_top(scalar) - 1;
- mask = BN_TBIT;
- word = bn_get_words(scalar)[i];
- while (!(word & mask))
- mask >>= 1;
- mask >>= 1;
- /* if top most bit was at word break, go to next word */
- if (!mask) {
- i--;
- mask = BN_TBIT;
- }
-
- for (; i >= 0; i--) {
- word = bn_get_words(scalar)[i];
- while (mask) {
- BN_consttime_swap(word & mask, x1, x2, group_top);
- BN_consttime_swap(word & mask, z1, z2, group_top);
- if (!gf2m_Madd(group, point->X, x2, z2, x1, z1, ctx))
- goto err;
- if (!gf2m_Mdouble(group, x1, z1, ctx))
- goto err;
- BN_consttime_swap(word & mask, x1, x2, group_top);
- BN_consttime_swap(word & mask, z1, z2, group_top);
- mask >>= 1;
- }
- mask = BN_TBIT;
- }
-
- /* convert out of "projective" coordinates */
- i = gf2m_Mxy(group, point->X, point->Y, x1, z1, x2, z2, ctx);
- if (i == 0)
- goto err;
- else if (i == 1) {
- if (!EC_POINT_set_to_infinity(group, r))
- goto err;
- } else {
- if (!BN_one(r->Z))
- goto err;
- r->Z_is_one = 1;
- }
-
- /* GF(2^m) field elements should always have BIGNUM::neg = 0 */
- BN_set_negative(r->X, 0);
- BN_set_negative(r->Y, 0);
-
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- return ret;
-}
-
-/*-
- * Computes the sum
- * scalar*group->generator + scalars[0]*points[0] + ... + scalars[num-1]*points[num-1]
- * gracefully ignoring NULL scalar values.
- */
-int ec_GF2m_simple_mul(const EC_GROUP *group, EC_POINT *r,
- const BIGNUM *scalar, size_t num,
- const EC_POINT *points[], const BIGNUM *scalars[],
- BN_CTX *ctx)
-{
- BN_CTX *new_ctx = NULL;
- int ret = 0;
- size_t i;
- EC_POINT *p = NULL;
- EC_POINT *acc = NULL;
-
- if (ctx == NULL) {
- ctx = new_ctx = BN_CTX_new();
- if (ctx == NULL)
- return 0;
- }
-
- /*
- * This implementation is more efficient than the wNAF implementation for
- * 2 or fewer points. Use the ec_wNAF_mul implementation for 3 or more
- * points, or if we can perform a fast multiplication based on
- * precomputation.
- */
- if ((scalar && (num > 1)) || (num > 2)
- || (num == 0 && EC_GROUP_have_precompute_mult(group))) {
- ret = ec_wNAF_mul(group, r, scalar, num, points, scalars, ctx);
- goto err;
- }
-
- if ((p = EC_POINT_new(group)) == NULL)
- goto err;
- if ((acc = EC_POINT_new(group)) == NULL)
- goto err;
-
- if (!EC_POINT_set_to_infinity(group, acc))
- goto err;
-
- if (scalar) {
- if (!ec_GF2m_montgomery_point_multiply
- (group, p, scalar, group->generator, ctx))
- goto err;
- if (BN_is_negative(scalar))
- if (!group->meth->invert(group, p, ctx))
- goto err;
- if (!group->meth->add(group, acc, acc, p, ctx))
- goto err;
- }
-
- for (i = 0; i < num; i++) {
- if (!ec_GF2m_montgomery_point_multiply
- (group, p, scalars[i], points[i], ctx))
- goto err;
- if (BN_is_negative(scalars[i]))
- if (!group->meth->invert(group, p, ctx))
- goto err;
- if (!group->meth->add(group, acc, acc, p, ctx))
- goto err;
- }
-
- if (!EC_POINT_copy(r, acc))
- goto err;
-
- ret = 1;
-
- err:
- EC_POINT_free(p);
- EC_POINT_free(acc);
- BN_CTX_free(new_ctx);
- return ret;
-}
-
-/*
- * Precomputation for point multiplication: fall back to wNAF methods because
- * ec_GF2m_simple_mul() uses ec_wNAF_mul() if appropriate
- */
-
-int ec_GF2m_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
-{
- return ec_wNAF_precompute_mult(group, ctx);
-}
-
-int ec_GF2m_have_precompute_mult(const EC_GROUP *group)
-{
- return ec_wNAF_have_precompute_mult(group);
-}
-
-#endif
diff --git a/crypto/ec/ec2_smpl.c b/crypto/ec/ec2_smpl.c
index 6bd5f9d..b73805a 100644
--- a/crypto/ec/ec2_smpl.c
+++ b/crypto/ec/ec2_smpl.c
@@ -47,14 +47,9 @@ const EC_METHOD *EC_GF2m_simple_method(void)
ec_GF2m_simple_cmp,
ec_GF2m_simple_make_affine,
ec_GF2m_simple_points_make_affine,
-
- /*
- * the following three method functions are defined in ec2_mult.c
- */
- ec_GF2m_simple_mul,
- ec_GF2m_precompute_mult,
- ec_GF2m_have_precompute_mult,
-
+ 0 /* mul */,
+ 0 /* precompute_mul */,
+ 0 /* have_precompute_mul */,
ec_GF2m_simple_field_mul,
ec_GF2m_simple_field_sqr,
ec_GF2m_simple_field_div,
diff --git a/crypto/ec/ec_lcl.h b/crypto/ec/ec_lcl.h
index 413a906..36c65c5 100644
--- a/crypto/ec/ec_lcl.h
+++ b/crypto/ec/ec_lcl.h
@@ -120,6 +120,23 @@ struct ec_method_st {
* EC_POINT_have_precompute_mult (default implementations are used if the
* 'mul' pointer is 0):
*/
+ /*-
+ * mul() calculates the value
+ *
+ * r := generator * scalar
+ * + points[0] * scalars[0]
+ * + ...
+ * + points[num-1] * scalars[num-1].
+ *
+ * For a fixed point multiplication (scalar != NULL, num == 0)
+ * or a variable point multiplication (scalar == NULL, num == 1),
+ * mul() must use a constant time algorithm: in both cases callers
+ * should provide an input scalar (either scalar or scalars[0])
+ * in the range [0, ec_group_order); for robustness, implementers
+ * should handle the case when the scalar has not been reduced, but
+ * may treat it as an unusual input, without any constant-timeness
+ * guarantee.
+ */
int (*mul) (const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
size_t num, const EC_POINT *points[], const BIGNUM *scalars[],
BN_CTX *);
@@ -426,14 +443,6 @@ int ec_GF2m_simple_field_sqr(const EC_GROUP *, BIGNUM *r, const BIGNUM *a,
int ec_GF2m_simple_field_div(const EC_GROUP *, BIGNUM *r, const BIGNUM *a,
const BIGNUM *b, BN_CTX *);
-/* method functions in ec2_mult.c */
-int ec_GF2m_simple_mul(const EC_GROUP *group, EC_POINT *r,
- const BIGNUM *scalar, size_t num,
- const EC_POINT *points[], const BIGNUM *scalars[],
- BN_CTX *);
-int ec_GF2m_precompute_mult(EC_GROUP *group, BN_CTX *ctx);
-int ec_GF2m_have_precompute_mult(const EC_GROUP *group);
-
#ifndef OPENSSL_NO_EC_NISTP_64_GCC_128
/* method functions in ecp_nistp224.c */
int ec_GFp_nistp224_group_init(EC_GROUP *group);
diff --git a/crypto/ec/ec_mult.c b/crypto/ec/ec_mult.c
index 6b5553c..1f34329 100644
--- a/crypto/ec/ec_mult.c
+++ b/crypto/ec/ec_mult.c
@@ -113,9 +113,9 @@ void EC_ec_pre_comp_free(EC_PRE_COMP *pre)
*
* At a high level, it is Montgomery ladder with conditional swaps.
*
- * It performs either a fixed scalar point multiplication
+ * It performs either a fixed point multiplication
* (scalar * generator)
- * when point is NULL, or a generic scalar point multiplication
+ * when point is NULL, or a variable point multiplication
* (scalar * point)
* when point is not NULL.
*
diff --git a/crypto/ec/ecdsa_ossl.c b/crypto/ec/ecdsa_ossl.c
index 2c9e5a8..7842851 100644
--- a/crypto/ec/ecdsa_ossl.c
+++ b/crypto/ec/ecdsa_ossl.c
@@ -105,23 +105,6 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
}
while (BN_is_zero(k));
- /*
- * We do not want timing information to leak the length of k, so we
- * compute G*k using an equivalent scalar of fixed bit-length.
- *
- * We unconditionally perform both of these additions to prevent a
- * small timing information leakage. We then choose the sum that is
- * one bit longer than the order. This guarantees the code
- * path used in the constant time implementations elsewhere.
- *
- * TODO: revisit the BN_copy aiming for a memory access agnostic
- * conditional copy.
- */
- if (!BN_add(r, k, order)
- || !BN_add(X, r, order)
- || !BN_copy(k, BN_num_bits(r) > order_bits ? r : X))
- goto err;
-
/* compute r the x-coordinate of generator * k */
if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
diff --git a/doc/man3/EC_POINT_add.pod b/doc/man3/EC_POINT_add.pod
index 3c047e1..21abf46 100644
--- a/doc/man3/EC_POINT_add.pod
+++ b/doc/man3/EC_POINT_add.pod
@@ -43,10 +43,12 @@ The functions EC_POINT_make_affine and EC_POINTs_make_affine force the internal
co-ordinate system. In the case of EC_POINTs_make_affine the value B<num> provides the number of points in the array B<points> to be
forced.
-EC_POINT_mul calculates the value generator * B<n> + B<q> * B<m> and stores the result in B<r>. The value B<n> may be NULL in which case the result is just B<q> * B<m>.
+EC_POINT_mul is a convenient interface to EC_POINTs_mul: it calculates the value generator * B<n> + B<q> * B<m> and stores the result in B<r>.
+The value B<n> may be NULL in which case the result is just B<q> * B<m> (variable point multiplication). Alternatively, both B<q> and B<m> may be NULL, and B<n> non-NULL, in which case the result is just generator * B<n> (fixed point multiplication).
+When performing a single fixed or variable point multiplication, the underlying implementation uses a constant time algorithm, when the input scalar (either B<n> or B<m>) is in the range [0, ec_group_order).
-EC_POINTs_mul calculates the value generator * B<n> + B<q[0]> * B<m[0]> + ... + B<q[num-1]> * B<m[num-1]>. As for EC_POINT_mul the value
-B<n> may be NULL.
+EC_POINTs_mul calculates the value generator * B<n> + B<q[0]> * B<m[0]> + ... + B<q[num-1]> * B<m[num-1]>. As for EC_POINT_mul the value B<n> may be NULL or B<num> may be zero.
+When performing a fixed point multiplication (B<n> is non-NULL and B<num> is 0) or a variable point multiplication (B<n> is NULL and B<num> is 1), the underlying implementation uses a constant time algorithm, when the input scalar (either B<n> or B<m[0]>) is in the range [0, ec_group_order).
The function EC_GROUP_precompute_mult stores multiples of the generator for faster point multiplication, whilst
EC_GROUP_have_precompute_mult tests whether precomputation has already been done. See L<EC_GROUP_copy(3)> for information
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