/*
- * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
*
- * Licensed under the OpenSSL license (the "License"). You may not use
+ * Licensed under the Apache License 2.0 (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 <string.h>
# include <openssl/err.h>
-# include "ec_lcl.h"
+# include "ec_local.h"
-# if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+# if defined(__SIZEOF_INT128__) && __SIZEOF_INT128__==16
/* even with gcc, the typedef won't work for 32-bit platforms */
typedef __uint128_t uint128_t; /* nonstandard; implemented by gcc on 64-bit
* platforms */
# else
-# error "Need GCC 3.1 or later to define type uint128_t"
+# error "Your compiler doesn't appear to support 128-bit integer types"
# endif
typedef uint8_t u8;
typedef uint64_t u64;
-typedef int64_t s64;
/*
* The underlying field. P521 operates over GF(2^521-1). We can serialise an
(*((limb *) & out[58])) = in[8];
}
-/* To preserve endianness when using BN_bn2bin and BN_bin2bn */
-static void flip_endian(u8 *out, const u8 *in, unsigned len)
-{
- unsigned i;
- for (i = 0; i < len; ++i)
- out[i] = in[len - 1 - i];
-}
-
/* BN_to_felem converts an OpenSSL BIGNUM into an felem */
static int BN_to_felem(felem out, const BIGNUM *bn)
{
- felem_bytearray b_in;
felem_bytearray b_out;
- unsigned num_bytes;
+ int num_bytes;
- /* BN_bn2bin eats leading zeroes */
- memset(b_out, 0, sizeof(b_out));
- num_bytes = BN_num_bytes(bn);
- if (num_bytes > sizeof b_out) {
+ if (BN_is_negative(bn)) {
ECerr(EC_F_BN_TO_FELEM, EC_R_BIGNUM_OUT_OF_RANGE);
return 0;
}
- if (BN_is_negative(bn)) {
+ num_bytes = BN_bn2lebinpad(bn, b_out, sizeof(b_out));
+ if (num_bytes < 0) {
ECerr(EC_F_BN_TO_FELEM, EC_R_BIGNUM_OUT_OF_RANGE);
return 0;
}
- num_bytes = BN_bn2bin(bn, b_in);
- flip_endian(b_out, b_in, num_bytes);
bin66_to_felem(out, b_out);
return 1;
}
/* felem_to_BN converts an felem into an OpenSSL BIGNUM */
static BIGNUM *felem_to_BN(BIGNUM *out, const felem in)
{
- felem_bytearray b_in, b_out;
- felem_to_bin66(b_in, in);
- flip_endian(b_out, b_in, sizeof b_out);
- return BN_bin2bn(b_out, sizeof b_out, out);
+ felem_bytearray b_out;
+ felem_to_bin66(b_out, in);
+ return BN_lebin2bn(b_out, sizeof(b_out), out);
}
/*-
static void felem_diff_128_64(largefelem out, const felem in)
{
/*
- * In order to prevent underflow, we add 0 mod p before subtracting.
+ * In order to prevent underflow, we add 64p mod p (which is equivalent
+ * to 0 mod p) before subtracting. p is 2^521 - 1, i.e. in binary a 521
+ * digit number with all bits set to 1. See "The representation of field
+ * elements" comment above for a description of how limbs are used to
+ * represent a number. 64p is represented with 8 limbs containing a number
+ * with 58 bits set and one limb with a number with 57 bits set.
*/
- static const limb two63m6 = (((limb) 1) << 62) - (((limb) 1) << 5);
- static const limb two63m5 = (((limb) 1) << 62) - (((limb) 1) << 4);
+ static const limb two63m6 = (((limb) 1) << 63) - (((limb) 1) << 6);
+ static const limb two63m5 = (((limb) 1) << 63) - (((limb) 1) << 5);
out[0] += two63m6 - in[0];
out[1] += two63m5 - in[1];
* We know that ftmp[i] < 2^63, therefore the only way that the top bit
* can be set is if is_zero was 0 before the decrement.
*/
- is_zero = ((s64) is_zero) >> 63;
+ is_zero = 0 - (is_zero >> 63);
is_p = ftmp[0] ^ kPrime[0];
is_p |= ftmp[1] ^ kPrime[1];
is_p |= ftmp[8] ^ kPrime[8];
is_p--;
- is_p = ((s64) is_p) >> 63;
+ is_p = 0 - (is_p >> 63);
is_zero |= is_p;
return is_zero;
}
-static int felem_is_zero_int(const felem in)
+static int felem_is_zero_int(const void *in)
{
return (int)(felem_is_zero(in) & ((limb) 1));
}
is_p &= is_p << 4;
is_p &= is_p << 2;
is_p &= is_p << 1;
- is_p = ((s64) is_p) >> 63;
+ is_p = 0 - (is_p >> 63);
is_p = ~is_p;
/* is_p is 0 iff |out| == 2^521-1 and all ones otherwise */
is_greater |= is_greater << 4;
is_greater |= is_greater << 2;
is_greater |= is_greater << 1;
- is_greater = ((s64) is_greater) >> 63;
+ is_greater = 0 - (is_greater >> 63);
out[0] -= kPrime[0] & is_greater;
out[1] -= kPrime[1] & is_greater;
* adapted for mixed addition (z2 = 1, or z2 = 0 for the point at infinity).
*
* This function includes a branch for checking whether the two input points
- * are equal (while not equal to the point at infinity). This case never
- * happens during single point multiplication, so there is no timing leak for
- * ECDH or ECDSA signing. */
+ * are equal (while not equal to the point at infinity). See comment below
+ * on constant-time.
+ */
static void point_add(felem x3, felem y3, felem z3,
const felem x1, const felem y1, const felem z1,
const int mixed, const felem x2, const felem y2,
/* ftmp5[i] < 2^61 */
if (x_equal && y_equal && !z1_is_zero && !z2_is_zero) {
+ /*
+ * This is obviously not constant-time but it will almost-never happen
+ * for ECDH / ECDSA. The case where it can happen is during scalar-mult
+ * where the intermediate value gets very close to the group order.
+ * Since |ec_GFp_nistp_recode_scalar_bits| produces signed digits for
+ * the scalar, it's possible for the intermediate value to be a small
+ * negative multiple of the base point, and for the final signed digit
+ * to be the same value. We believe that this only occurs for the scalar
+ * 1fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+ * ffffffa51868783bf2f966b7fcc0148f709a5d03bb5c9b8899c47aebb6fb
+ * 71e913863f7, in that case the penultimate intermediate is -9G and
+ * the final digit is also -9G. Since this only happens for a single
+ * scalar, the timing leak is irrelevant. (Any attacker who wanted to
+ * check whether a secret scalar was that exact value, can already do
+ * so.)
+ */
point_double(x3, y3, z3, x1, y1, z1);
return;
}
ec_GFp_nist_field_mul,
ec_GFp_nist_field_sqr,
0 /* field_div */ ,
+ ec_GFp_simple_field_inv,
0 /* field_encode */ ,
0 /* field_decode */ ,
0, /* field_set_to_one */
ec_key_simple_generate_public_key,
0, /* keycopy */
0, /* keyfinish */
- ecdh_simple_compute_key
+ ecdh_simple_compute_key,
+ ecdsa_simple_sign_setup,
+ ecdsa_simple_sign_sig,
+ ecdsa_simple_verify_sig,
+ 0, /* field_inverse_mod_ord */
+ 0, /* blind_coordinates */
+ 0, /* ladder_pre */
+ 0, /* ladder_step */
+ 0 /* ladder_post */
};
return &ret;
* FUNCTIONS TO MANAGE PRECOMPUTATION
*/
-static NISTP521_PRE_COMP *nistp521_pre_comp_new()
+static NISTP521_PRE_COMP *nistp521_pre_comp_new(void)
{
NISTP521_PRE_COMP *ret = OPENSSL_zalloc(sizeof(*ret));
BN_CTX *ctx)
{
int ret = 0;
- BN_CTX *new_ctx = NULL;
BIGNUM *curve_p, *curve_a, *curve_b;
+#ifndef FIPS_MODE
+ BN_CTX *new_ctx = NULL;
if (ctx == NULL)
- if ((ctx = new_ctx = BN_CTX_new()) == NULL)
- return 0;
+ ctx = new_ctx = BN_CTX_new();
+#endif
+ if (ctx == NULL)
+ return 0;
+
BN_CTX_start(ctx);
- if (((curve_p = BN_CTX_get(ctx)) == NULL) ||
- ((curve_a = BN_CTX_get(ctx)) == NULL) ||
- ((curve_b = BN_CTX_get(ctx)) == NULL))
+ curve_p = BN_CTX_get(ctx);
+ curve_a = BN_CTX_get(ctx);
+ curve_b = BN_CTX_get(ctx);
+ if (curve_b == NULL)
goto err;
BN_bin2bn(nistp521_curve_params[0], sizeof(felem_bytearray), curve_p);
BN_bin2bn(nistp521_curve_params[1], sizeof(felem_bytearray), curve_a);
ret = ec_GFp_simple_group_set_curve(group, p, a, b, ctx);
err:
BN_CTX_end(ctx);
+#ifndef FIPS_MODE
BN_CTX_free(new_ctx);
+#endif
return ret;
}
sizeof(felem),
tmp_felems,
(void (*)(void *))felem_one,
- (int (*)(const void *))
felem_is_zero_int,
(void (*)(void *, const void *))
felem_assign,
int ret = 0;
int j;
int mixed = 0;
- BN_CTX *new_ctx = NULL;
BIGNUM *x, *y, *z, *tmp_scalar;
felem_bytearray g_secret;
felem_bytearray *secrets = NULL;
felem (*pre_comp)[17][3] = NULL;
felem *tmp_felems = NULL;
- felem_bytearray tmp;
- unsigned i, num_bytes;
+ unsigned i;
+ int num_bytes;
int have_pre_comp = 0;
size_t num_points = num;
felem x_in, y_in, z_in, x_out, y_out, z_out;
const EC_POINT *p = NULL;
const BIGNUM *p_scalar = NULL;
- if (ctx == NULL)
- if ((ctx = new_ctx = BN_CTX_new()) == NULL)
- return 0;
BN_CTX_start(ctx);
- if (((x = BN_CTX_get(ctx)) == NULL) ||
- ((y = BN_CTX_get(ctx)) == NULL) ||
- ((z = BN_CTX_get(ctx)) == NULL) ||
- ((tmp_scalar = BN_CTX_get(ctx)) == NULL))
+ x = BN_CTX_get(ctx);
+ y = BN_CTX_get(ctx);
+ z = BN_CTX_get(ctx);
+ tmp_scalar = BN_CTX_get(ctx);
+ if (tmp_scalar == NULL)
goto err;
if (scalar != NULL) {
* i.e., they contribute nothing to the linear combination
*/
for (i = 0; i < num_points; ++i) {
- if (i == num)
+ if (i == num) {
/*
* we didn't have a valid precomputation, so we pick the
* generator
*/
- {
p = EC_GROUP_get0_generator(group);
p_scalar = scalar;
- } else
+ } else {
/* the i^th point */
- {
p = points[i];
p_scalar = scalars[i];
}
ECerr(EC_F_EC_GFP_NISTP521_POINTS_MUL, ERR_R_BN_LIB);
goto err;
}
- num_bytes = BN_bn2bin(tmp_scalar, tmp);
- } else
- num_bytes = BN_bn2bin(p_scalar, tmp);
- flip_endian(secrets[i], tmp, num_bytes);
+ num_bytes = BN_bn2lebinpad(tmp_scalar,
+ secrets[i], sizeof(secrets[i]));
+ } else {
+ num_bytes = BN_bn2lebinpad(p_scalar,
+ secrets[i], sizeof(secrets[i]));
+ }
+ if (num_bytes < 0) {
+ ECerr(EC_F_EC_GFP_NISTP521_POINTS_MUL, ERR_R_BN_LIB);
+ goto err;
+ }
/* precompute multiples */
if ((!BN_to_felem(x_out, p->X)) ||
(!BN_to_felem(y_out, p->Y)) ||
ECerr(EC_F_EC_GFP_NISTP521_POINTS_MUL, ERR_R_BN_LIB);
goto err;
}
- num_bytes = BN_bn2bin(tmp_scalar, tmp);
- } else
- num_bytes = BN_bn2bin(scalar, tmp);
- flip_endian(g_secret, tmp, num_bytes);
+ num_bytes = BN_bn2lebinpad(tmp_scalar, g_secret, sizeof(g_secret));
+ } else {
+ num_bytes = BN_bn2lebinpad(scalar, g_secret, sizeof(g_secret));
+ }
/* do the multiplication with generator precomputation */
batch_mul(x_out, y_out, z_out,
(const felem_bytearray(*))secrets, num_points,
g_secret,
mixed, (const felem(*)[17][3])pre_comp,
(const felem(*)[3])g_pre_comp);
- } else
+ } else {
/* do the multiplication without generator precomputation */
batch_mul(x_out, y_out, z_out,
(const felem_bytearray(*))secrets, num_points,
NULL, mixed, (const felem(*)[17][3])pre_comp, NULL);
+ }
/* reduce the output to its unique minimal representation */
felem_contract(x_in, x_out);
felem_contract(y_in, y_out);
err:
BN_CTX_end(ctx);
EC_POINT_free(generator);
- BN_CTX_free(new_ctx);
OPENSSL_free(secrets);
OPENSSL_free(pre_comp);
OPENSSL_free(tmp_felems);
int ret = 0;
NISTP521_PRE_COMP *pre = NULL;
int i, j;
- BN_CTX *new_ctx = NULL;
BIGNUM *x, *y;
EC_POINT *generator = NULL;
felem tmp_felems[16];
+#ifndef FIPS_MODE
+ BN_CTX *new_ctx = NULL;
+#endif
/* throw away old precomputation */
EC_pre_comp_free(group);
+
+#ifndef FIPS_MODE
if (ctx == NULL)
- if ((ctx = new_ctx = BN_CTX_new()) == NULL)
- return 0;
+ ctx = new_ctx = BN_CTX_new();
+#endif
+ if (ctx == NULL)
+ return 0;
+
BN_CTX_start(ctx);
- if (((x = BN_CTX_get(ctx)) == NULL) || ((y = BN_CTX_get(ctx)) == NULL))
+ x = BN_CTX_get(ctx);
+ y = BN_CTX_get(ctx);
+ if (y == NULL)
goto err;
/* get the generator */
if (group->generator == NULL)
goto err;
BN_bin2bn(nistp521_curve_params[3], sizeof(felem_bytearray), x);
BN_bin2bn(nistp521_curve_params[4], sizeof(felem_bytearray), y);
- if (!EC_POINT_set_affine_coordinates_GFp(group, generator, x, y, ctx))
+ if (!EC_POINT_set_affine_coordinates(group, generator, x, y, ctx))
goto err;
if ((pre = nistp521_pre_comp_new()) == NULL)
goto err;
err:
BN_CTX_end(ctx);
EC_POINT_free(generator);
+#ifndef FIPS_MODE
BN_CTX_free(new_ctx);
+#endif
EC_nistp521_pre_comp_free(pre);
return ret;
}