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Import OpenSSL 1.0.2q

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This commit is contained in:
Steve Dower
2018-12-07 11:08:57 -08:00
parent 4b1c388f4d
commit 4155d3c2bd
75 changed files with 3071 additions and 1937 deletions
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248
crypto/ec/ec_mult.c
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@@ -3,7 +3,7 @@
* Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
*/
/* ====================================================================
* Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
* Copyright (c) 1998-2018 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -310,6 +310,224 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
return r;
}
#define EC_POINT_BN_set_flags(P, flags) do { \
BN_set_flags(&(P)->X, (flags)); \
BN_set_flags(&(P)->Y, (flags)); \
BN_set_flags(&(P)->Z, (flags)); \
} while(0)
/*-
* This functions computes (in constant time) a point multiplication over the
* EC group.
*
* At a high level, it is Montgomery ladder with conditional swaps.
*
* It performs either a fixed scalar point multiplication
* (scalar * generator)
* when point is NULL, or a generic scalar point multiplication
* (scalar * point)
* when point is not NULL.
*
* scalar should be in the range [0,n) otherwise all constant time bets are off.
*
* NB: This says nothing about EC_POINT_add and EC_POINT_dbl,
* which of course are not constant time themselves.
*
* The product is stored in r.
*
* Returns 1 on success, 0 otherwise.
*/
static int ec_mul_consttime(const EC_GROUP *group, EC_POINT *r,
const BIGNUM *scalar, const EC_POINT *point,
BN_CTX *ctx)
{
int i, cardinality_bits, group_top, kbit, pbit, Z_is_one;
EC_POINT *s = NULL;
BIGNUM *k = NULL;
BIGNUM *lambda = NULL;
BIGNUM *cardinality = NULL;
BN_CTX *new_ctx = NULL;
int ret = 0;
if (ctx == NULL && (ctx = new_ctx = BN_CTX_new()) == NULL)
return 0;
BN_CTX_start(ctx);
s = EC_POINT_new(group);
if (s == NULL)
goto err;
if (point == NULL) {
if (!EC_POINT_copy(s, group->generator))
goto err;
} else {
if (!EC_POINT_copy(s, point))
goto err;
}
EC_POINT_BN_set_flags(s, BN_FLG_CONSTTIME);
cardinality = BN_CTX_get(ctx);
lambda = BN_CTX_get(ctx);
k = BN_CTX_get(ctx);
if (k == NULL || !BN_mul(cardinality, &group->order, &group->cofactor, ctx))
goto err;
/*
* Group cardinalities are often on a word boundary.
* So when we pad the scalar, some timing diff might
* pop if it needs to be expanded due to carries.
* So expand ahead of time.
*/
cardinality_bits = BN_num_bits(cardinality);
group_top = cardinality->top;
if ((bn_wexpand(k, group_top + 2) == NULL)
|| (bn_wexpand(lambda, group_top + 2) == NULL))
goto err;
if (!BN_copy(k, scalar))
goto err;
BN_set_flags(k, BN_FLG_CONSTTIME);
if ((BN_num_bits(k) > cardinality_bits) || (BN_is_negative(k))) {
/*-
* this is an unusual input, and we don't guarantee
* constant-timeness
*/
if (!BN_nnmod(k, k, cardinality, ctx))
goto err;
}
if (!BN_add(lambda, k, cardinality))
goto err;
BN_set_flags(lambda, BN_FLG_CONSTTIME);
if (!BN_add(k, lambda, cardinality))
goto err;
/*
* lambda := scalar + cardinality
* k := scalar + 2*cardinality
*/
kbit = BN_is_bit_set(lambda, cardinality_bits);
BN_consttime_swap(kbit, k, lambda, group_top + 2);
group_top = group->field.top;
if ((bn_wexpand(&s->X, group_top) == NULL)
|| (bn_wexpand(&s->Y, group_top) == NULL)
|| (bn_wexpand(&s->Z, group_top) == NULL)
|| (bn_wexpand(&r->X, group_top) == NULL)
|| (bn_wexpand(&r->Y, group_top) == NULL)
|| (bn_wexpand(&r->Z, group_top) == NULL))
goto err;
/* top bit is a 1, in a fixed pos */
if (!EC_POINT_copy(r, s))
goto err;
EC_POINT_BN_set_flags(r, BN_FLG_CONSTTIME);
if (!EC_POINT_dbl(group, s, s, ctx))
goto err;
pbit = 0;
#define EC_POINT_CSWAP(c, a, b, w, t) do { \
BN_consttime_swap(c, &(a)->X, &(b)->X, w); \
BN_consttime_swap(c, &(a)->Y, &(b)->Y, w); \
BN_consttime_swap(c, &(a)->Z, &(b)->Z, w); \
t = ((a)->Z_is_one ^ (b)->Z_is_one) & (c); \
(a)->Z_is_one ^= (t); \
(b)->Z_is_one ^= (t); \
} while(0)
/*-
* The ladder step, with branches, is
*
* k[i] == 0: S = add(R, S), R = dbl(R)
* k[i] == 1: R = add(S, R), S = dbl(S)
*
* Swapping R, S conditionally on k[i] leaves you with state
*
* k[i] == 0: T, U = R, S
* k[i] == 1: T, U = S, R
*
* Then perform the ECC ops.
*
* U = add(T, U)
* T = dbl(T)
*
* Which leaves you with state
*
* k[i] == 0: U = add(R, S), T = dbl(R)
* k[i] == 1: U = add(S, R), T = dbl(S)
*
* Swapping T, U conditionally on k[i] leaves you with state
*
* k[i] == 0: R, S = T, U
* k[i] == 1: R, S = U, T
*
* Which leaves you with state
*
* k[i] == 0: S = add(R, S), R = dbl(R)
* k[i] == 1: R = add(S, R), S = dbl(S)
*
* So we get the same logic, but instead of a branch it's a
* conditional swap, followed by ECC ops, then another conditional swap.
*
* Optimization: The end of iteration i and start of i-1 looks like
*
* ...
* CSWAP(k[i], R, S)
* ECC
* CSWAP(k[i], R, S)
* (next iteration)
* CSWAP(k[i-1], R, S)
* ECC
* CSWAP(k[i-1], R, S)
* ...
*
* So instead of two contiguous swaps, you can merge the condition
* bits and do a single swap.
*
* k[i] k[i-1] Outcome
* 0 0 No Swap
* 0 1 Swap
* 1 0 Swap
* 1 1 No Swap
*
* This is XOR. pbit tracks the previous bit of k.
*/
for (i = cardinality_bits - 1; i >= 0; i--) {
kbit = BN_is_bit_set(k, i) ^ pbit;
EC_POINT_CSWAP(kbit, r, s, group_top, Z_is_one);
if (!EC_POINT_add(group, s, r, s, ctx))
goto err;
if (!EC_POINT_dbl(group, r, r, ctx))
goto err;
/*
* pbit logic merges this cswap with that of the
* next iteration
*/
pbit ^= kbit;
}
/* one final cswap to move the right value into r */
EC_POINT_CSWAP(pbit, r, s, group_top, Z_is_one);
#undef EC_POINT_CSWAP
ret = 1;
err:
EC_POINT_free(s);
BN_CTX_end(ctx);
BN_CTX_free(new_ctx);
return ret;
}
#undef EC_POINT_BN_set_flags
/*
* TODO: table should be optimised for the wNAF-based implementation,
* sometimes smaller windows will give better performance (thus the
@@ -369,6 +587,34 @@ int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
return EC_POINT_set_to_infinity(group, r);
}
if (!BN_is_zero(&group->order) && !BN_is_zero(&group->cofactor)) {
/*-
* Handle the common cases where the scalar is secret, enforcing a constant
* time scalar multiplication algorithm.
*/
if ((scalar != NULL) && (num == 0)) {
/*-
* In this case we want to compute scalar * GeneratorPoint: this
* codepath is reached most prominently by (ephemeral) key generation
* of EC cryptosystems (i.e. ECDSA keygen and sign setup, ECDH
* keygen/first half), where the scalar is always secret. This is why
* we ignore if BN_FLG_CONSTTIME is actually set and we always call the
* constant time version.
*/
return ec_mul_consttime(group, r, scalar, NULL, ctx);
}
if ((scalar == NULL) && (num == 1)) {
/*-
* In this case we want to compute scalar * GenericPoint: this codepath
* is reached most prominently by the second half of ECDH, where the
* secret scalar is multiplied by the peer's public point. To protect
* the secret scalar, we ignore if BN_FLG_CONSTTIME is actually set and
* we always call the constant time version.
*/
return ec_mul_consttime(group, r, scalars[0], points[0], ctx);
}
}
for (i = 0; i < num; i++) {
if (group->meth != points[i]->meth) {
ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);