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components/wpa_supplicant/esp_supplicant/src/crypto/crypto_mbedtls-ec.c
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/*
* SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#ifdef ESP_PLATFORM
#include "esp_system.h"
#include "mbedtls/bignum.h"
#endif
#include "utils/includes.h"
#include "utils/common.h"
#include "crypto.h"
#include "sha256.h"
#include "random.h"
#include "mbedtls/ecp.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/pk.h"
#include "mbedtls/ecdh.h"
#include "mbedtls/sha256.h"
#include "mbedtls/asn1write.h"
#include "mbedtls/error.h"
#include "mbedtls/oid.h"
#define ECP_PRV_DER_MAX_BYTES ( 29 + 3 * MBEDTLS_ECP_MAX_BYTES )
#define ECP_PUB_DER_MAX_BYTES ( 30 + 2 * MBEDTLS_ECP_MAX_BYTES )
#ifdef CONFIG_MBEDTLS_ECDH_LEGACY_CONTEXT
#define ACCESS_ECDH(S, var) S->MBEDTLS_PRIVATE(var)
#else
#define ACCESS_ECDH(S, var) S->MBEDTLS_PRIVATE(ctx).MBEDTLS_PRIVATE(mbed_ecdh).MBEDTLS_PRIVATE(var)
#endif
#ifdef CONFIG_ECC
static int crypto_rng_wrapper(void *ctx, unsigned char *buf, size_t len)
{
return random_get_bytes(buf, len);
}
struct crypto_ec *crypto_ec_init(int group)
{
mbedtls_ecp_group *e;
mbedtls_ecp_group_id grp_id;
/* IANA registry to mbedtls internal mapping*/
switch (group) {
case IANA_SECP256R1:
/* For now just support NIST-P256.
* This is of type "short Weierstrass".
*/
grp_id = MBEDTLS_ECP_DP_SECP256R1;
break;
default:
return NULL;
}
e = os_zalloc(sizeof(*e));
if (!e) {
return NULL;
}
mbedtls_ecp_group_init(e);
if (mbedtls_ecp_group_load(e, grp_id)) {
mbedtls_ecp_group_free(e);
os_free(e);
e = NULL;
}
return (struct crypto_ec *)e;
}
void crypto_ec_deinit(struct crypto_ec *e)
{
if (!e) {
return;
}
mbedtls_ecp_group_free((mbedtls_ecp_group *)e);
os_free(e);
}
struct crypto_ec_point *crypto_ec_point_init(struct crypto_ec *e)
{
mbedtls_ecp_point *pt;
if (!e) {
return NULL;
}
pt = os_zalloc(sizeof(mbedtls_ecp_point));
if (!pt) {
return NULL;
}
mbedtls_ecp_point_init(pt);
return (struct crypto_ec_point *) pt;
}
size_t crypto_ec_prime_len(struct crypto_ec *e)
{
return mbedtls_mpi_size(&((mbedtls_ecp_group *)e)->P);
}
size_t crypto_ec_order_len(struct crypto_ec *e)
{
return mbedtls_mpi_size(&((mbedtls_ecp_group *)e)->N);
}
size_t crypto_ec_prime_len_bits(struct crypto_ec *e)
{
return mbedtls_mpi_bitlen(&((mbedtls_ecp_group *)e)->P);
}
struct crypto_ec_group *crypto_ec_get_group_byname(const char *name)
{
mbedtls_ecp_group *e;
const mbedtls_ecp_curve_info *curve = mbedtls_ecp_curve_info_from_name(name);
e = os_zalloc(sizeof(*e));
if (!e) {
return NULL;
}
mbedtls_ecp_group_init(e);
if (mbedtls_ecp_group_load(e, curve->grp_id)) {
mbedtls_ecp_group_free(e);
os_free(e);
e = NULL;
}
return (struct crypto_ec_group *)e;
}
const struct crypto_bignum *crypto_ec_get_prime(struct crypto_ec *e)
{
return (const struct crypto_bignum *) & ((mbedtls_ecp_group *)e)->P;
}
const struct crypto_bignum *crypto_ec_get_order(struct crypto_ec *e)
{
return (const struct crypto_bignum *) & ((mbedtls_ecp_group *)e)->N;
}
const struct crypto_bignum * crypto_ec_get_b(struct crypto_ec *e)
{
return (const struct crypto_bignum *) & ((mbedtls_ecp_group *)e)->B;
}
void crypto_ec_point_deinit(struct crypto_ec_point *p, int clear)
{
mbedtls_ecp_point_free((mbedtls_ecp_point *) p);
os_free(p);
}
int crypto_ec_point_to_bin(struct crypto_ec *e,
const struct crypto_ec_point *point, u8 *x, u8 *y)
{
int len = mbedtls_mpi_size(&((mbedtls_ecp_group *)e)->P);
if (x) {
if (crypto_bignum_to_bin((struct crypto_bignum *) & ((mbedtls_ecp_point *) point)->MBEDTLS_PRIVATE(X),
x, len, len) < 0) {
return -1;
}
}
if (y) {
if (crypto_bignum_to_bin((struct crypto_bignum *) & ((mbedtls_ecp_point *) point)->MBEDTLS_PRIVATE(Y),
y, len, len) < 0) {
return -1;
}
}
return 0;
}
int crypto_ec_get_affine_coordinates(struct crypto_ec *e, struct crypto_ec_point *pt,
struct crypto_bignum *x, struct crypto_bignum *y)
{
int ret = -1;
mbedtls_ecp_point *point = (mbedtls_ecp_point *)pt;
if (!mbedtls_ecp_is_zero(point) && (mbedtls_mpi_cmp_int(&point->MBEDTLS_PRIVATE(Z), 1) == 0)) {
// Affine coordinates mean that z should be 1,
wpa_printf(MSG_ERROR, "Z coordinate is neither 0 or 1");
return -1;
}
if (x) {
MBEDTLS_MPI_CHK(mbedtls_mpi_copy((mbedtls_mpi*) x, &((mbedtls_ecp_point*)point)->MBEDTLS_PRIVATE(X)));
}
if (y) {
MBEDTLS_MPI_CHK(mbedtls_mpi_copy((mbedtls_mpi*) y, &((mbedtls_ecp_point*)point)->MBEDTLS_PRIVATE(Y)));
}
return 0;
cleanup:
return ret;
}
struct crypto_ec_point *crypto_ec_point_from_bin(struct crypto_ec *e,
const u8 *val)
{
mbedtls_ecp_point *pt;
int len, ret;
if (!e) {
return NULL;
}
len = mbedtls_mpi_size(&((mbedtls_ecp_group *)e)->P);
pt = os_zalloc(sizeof(mbedtls_ecp_point));
if (!pt) {
return NULL;
}
mbedtls_ecp_point_init(pt);
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&pt->MBEDTLS_PRIVATE(X), val, len));
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&pt->MBEDTLS_PRIVATE(Y), val + len, len));
MBEDTLS_MPI_CHK(mbedtls_mpi_lset((&pt->MBEDTLS_PRIVATE(Z)), 1));
return (struct crypto_ec_point *) pt;
cleanup:
mbedtls_ecp_point_free(pt);
os_free(pt);
return NULL;
}
int crypto_ec_point_add(struct crypto_ec *e, const struct crypto_ec_point *a,
const struct crypto_ec_point *b,
struct crypto_ec_point *c)
{
int ret;
mbedtls_mpi one;
mbedtls_mpi_init(&one);
MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&one, 1));
MBEDTLS_MPI_CHK(mbedtls_ecp_muladd((mbedtls_ecp_group *)e, (mbedtls_ecp_point *)c, &one, (const mbedtls_ecp_point *)a, &one, (const mbedtls_ecp_point *)b));
cleanup:
mbedtls_mpi_free(&one);
return ret ? -1 : 0;
}
int crypto_ec_point_mul(struct crypto_ec *e, const struct crypto_ec_point *p,
const struct crypto_bignum *b,
struct crypto_ec_point *res)
{
int ret;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_entropy_init(&entropy);
mbedtls_ctr_drbg_init(&ctr_drbg);
MBEDTLS_MPI_CHK(mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
NULL, 0));
MBEDTLS_MPI_CHK(mbedtls_ecp_mul((mbedtls_ecp_group *)e,
(mbedtls_ecp_point *) res,
(const mbedtls_mpi *)b,
(const mbedtls_ecp_point *)p,
mbedtls_ctr_drbg_random,
&ctr_drbg));
cleanup:
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
return ret ? -1 : 0;
}
/* Currently mbedtls does not have any function for inverse
* This function calculates inverse of a point.
* Set R = -P
*/
static int ecp_opp(const mbedtls_ecp_group *grp, mbedtls_ecp_point *R, const mbedtls_ecp_point *P)
{
int ret = 0;
/* Copy */
if (R != P) {
MBEDTLS_MPI_CHK(mbedtls_ecp_copy(R, P));
}
/* In-place opposite */
if (mbedtls_mpi_cmp_int(&R->MBEDTLS_PRIVATE(Y), 0) != 0) {
MBEDTLS_MPI_CHK(mbedtls_mpi_sub_mpi(&R->MBEDTLS_PRIVATE(Y), &grp->P, &R->MBEDTLS_PRIVATE(Y)));
}
cleanup:
return (ret);
}
int crypto_ec_point_invert(struct crypto_ec *e, struct crypto_ec_point *p)
{
return ecp_opp((mbedtls_ecp_group *)e, (mbedtls_ecp_point *) p, (mbedtls_ecp_point *) p) ? -1 : 0;
}
int crypto_ec_point_solve_y_coord(struct crypto_ec *e,
struct crypto_ec_point *p,
const struct crypto_bignum *x, int y_bit)
{
mbedtls_mpi temp;
mbedtls_mpi *y_sqr, *y;
mbedtls_mpi_init(&temp);
int ret = 0;
y = &((mbedtls_ecp_point *)p)->MBEDTLS_PRIVATE(Y);
/* Faster way to find sqrt
* Works only with curves having prime p
* such that p ≡ 3 (mod 4)
* y_ = (y2 ^ ((p+1)/4)) mod p
*
* if LSB of both x and y are same: y = y_
* else y = p - y_
* y_bit is LSB of x
*/
y_bit = (y_bit != 0);
y_sqr = (mbedtls_mpi *) crypto_ec_point_compute_y_sqr(e, x);
if (y_sqr) {
MBEDTLS_MPI_CHK(mbedtls_mpi_add_int(&temp, &((mbedtls_ecp_group *)e)->P, 1));
MBEDTLS_MPI_CHK(mbedtls_mpi_div_int(&temp, NULL, &temp, 4));
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(y, y_sqr, &temp, &((mbedtls_ecp_group *)e)->P, NULL));
if (y_bit != mbedtls_mpi_get_bit(y, 0)) {
MBEDTLS_MPI_CHK(mbedtls_mpi_sub_mpi(y, &((mbedtls_ecp_group *)e)->P, y));
}
MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&((mbedtls_ecp_point*)p)->MBEDTLS_PRIVATE(X), (const mbedtls_mpi*) x));
MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&((mbedtls_ecp_point *)p)->MBEDTLS_PRIVATE(Z), 1));
} else {
ret = 1;
}
cleanup:
mbedtls_mpi_free(&temp);
mbedtls_mpi_free(y_sqr);
os_free(y_sqr);
return ret ? -1 : 0;
}
int crypto_get_order(struct crypto_ec_group *group, struct crypto_bignum *x)
{
return mbedtls_mpi_copy((mbedtls_mpi *) x, &((mbedtls_ecp_group *)group)->N);
}
struct crypto_bignum *crypto_ec_point_compute_y_sqr(struct crypto_ec *e,
const struct crypto_bignum *x)
{
mbedtls_mpi temp, temp2, num;
int ret = 0;
mbedtls_mpi *y_sqr = os_zalloc(sizeof(mbedtls_mpi));
if (!y_sqr) {
return NULL;
}
mbedtls_mpi_init(&temp);
mbedtls_mpi_init(&temp2);
mbedtls_mpi_init(&num);
mbedtls_mpi_init(y_sqr);
/* y^2 = x^3 + ax + b mod P */
/* X*X*X is faster on esp32 whereas X^3 is faster on other chips */
#if CONFIG_IDF_TARGET_ESP32
/* Calculate x*x*x mod P*/
MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&temp, (const mbedtls_mpi *) x, (const mbedtls_mpi *) x));
MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&temp, &temp, (const mbedtls_mpi *) x));
MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&temp, &temp, &((mbedtls_ecp_group *)e)->P));
#else
/* Calculate x^3 mod P*/
MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&num, 3));
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&temp, (const mbedtls_mpi *) x, &num, &((mbedtls_ecp_group *)e)->P, NULL));
#endif
/* Calculate ax mod P*/
MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&num, -3));
MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&temp2, (const mbedtls_mpi *) x, &num));
MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&temp2, &temp2, &((mbedtls_ecp_group *)e)->P));
/* Calculate ax + b mod P. Note that b is already < P*/
MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&temp2, &temp2, &((mbedtls_ecp_group *)e)->B));
MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&temp2, &temp2, &((mbedtls_ecp_group *)e)->P));
/* Calculate x^3 + ax + b mod P*/
MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&temp2, &temp2, &temp));
MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(y_sqr, &temp2, &((mbedtls_ecp_group *)e)->P));
cleanup:
mbedtls_mpi_free(&temp);
mbedtls_mpi_free(&temp2);
mbedtls_mpi_free(&num);
if (ret) {
mbedtls_mpi_free(y_sqr);
os_free(y_sqr);
return NULL;
} else {
return (struct crypto_bignum *) y_sqr;
}
}
int crypto_ec_point_is_at_infinity(struct crypto_ec *e,
const struct crypto_ec_point *p)
{
return mbedtls_ecp_is_zero((mbedtls_ecp_point *) p);
}
int crypto_ec_point_is_on_curve(struct crypto_ec *e,
const struct crypto_ec_point *p)
{
mbedtls_mpi y_sqr_lhs, *y_sqr_rhs = NULL, two;
int ret = 0, on_curve = 0;
mbedtls_mpi_init(&y_sqr_lhs);
mbedtls_mpi_init(&two);
/* Calculate y^2 mod P*/
MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&two, 2));
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&y_sqr_lhs, &((const mbedtls_ecp_point *)p)->MBEDTLS_PRIVATE(Y), &two, &((mbedtls_ecp_group *)e)->P, NULL));
y_sqr_rhs = (mbedtls_mpi *) crypto_ec_point_compute_y_sqr(e, (const struct crypto_bignum *) & ((const mbedtls_ecp_point *)p)->MBEDTLS_PRIVATE(X));
if (y_sqr_rhs && (mbedtls_mpi_cmp_mpi(y_sqr_rhs, &y_sqr_lhs) == 0)) {
on_curve = 1;
}
cleanup:
mbedtls_mpi_free(&y_sqr_lhs);
mbedtls_mpi_free(&two);
mbedtls_mpi_free(y_sqr_rhs);
os_free(y_sqr_rhs);
return (ret == 0) && (on_curve == 1);
}
int crypto_ec_point_cmp(const struct crypto_ec *e,
const struct crypto_ec_point *a,
const struct crypto_ec_point *b)
{
return mbedtls_ecp_point_cmp((const mbedtls_ecp_point *) a,
(const mbedtls_ecp_point *) b);
}
int crypto_ec_key_compare(struct crypto_ec_key *key1, struct crypto_ec_key *key2)
{
int ret = 0;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_entropy_init(&entropy);
mbedtls_ctr_drbg_init(&ctr_drbg);
MBEDTLS_MPI_CHK(mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0));
if (mbedtls_pk_check_pair((mbedtls_pk_context *)key1, (mbedtls_pk_context *)key2, mbedtls_ctr_drbg_random, &ctr_drbg) < 0) {
goto cleanup;
}
ret = 1;
cleanup:
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
return ret;
}
void crypto_debug_print_point(const char *title, struct crypto_ec *e,
const struct crypto_ec_point *point)
{
u8 x[32], y[32];
if (crypto_ec_point_to_bin(e, point, x, y) < 0) {
wpa_printf(MSG_ERROR, "error: failed to get corrdinates");
return;
}
wpa_hexdump(MSG_ERROR, "x:", x, 32);
wpa_hexdump(MSG_ERROR, "y:", y, 32);
}
static struct crypto_ec_key *crypto_alloc_key(void)
{
mbedtls_pk_context *key = os_malloc(sizeof(*key));
if (!key) {
wpa_printf(MSG_ERROR, "%s: memory allocation failed", __func__);
return NULL;
}
mbedtls_pk_init(key);
return (struct crypto_ec_key *)key;
}
struct crypto_ec_key * crypto_ec_key_set_pub(const struct crypto_ec_group *group,
const u8 *buf, size_t len)
{
mbedtls_ecp_point *point = NULL;
struct crypto_ec_key *pkey = NULL;
int ret;
mbedtls_pk_context *key = (mbedtls_pk_context *)crypto_alloc_key();
mbedtls_ecp_group *ecp_grp = (mbedtls_ecp_group *)group;
if (!key) {
wpa_printf(MSG_ERROR, "%s: memory allocation failed", __func__);
return NULL;
}
point = (mbedtls_ecp_point *)crypto_ec_point_from_bin((struct crypto_ec *)group, buf);
if (!point) {
wpa_printf(MSG_ERROR, "%s: Point initialization failed", __func__);
goto fail;
}
if (crypto_ec_point_is_at_infinity((struct crypto_ec *)group, (struct crypto_ec_point *)point)) {
wpa_printf(MSG_ERROR, "Point is at infinity");
goto fail;
}
if (!crypto_ec_point_is_on_curve((struct crypto_ec *)group, (struct crypto_ec_point *)point)) {
wpa_printf(MSG_ERROR, "Point not on curve");
goto fail;
}
if (mbedtls_ecp_check_pubkey(ecp_grp, point) < 0) {
// ideally should have failed in upper condition, duplicate code??
wpa_printf(MSG_ERROR, "Invalid key");
goto fail;
}
/* Assign values */
if ((ret = mbedtls_pk_setup(key,
mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY))) != 0) {
goto fail;
}
mbedtls_ecp_copy(&mbedtls_pk_ec(*key)->MBEDTLS_PRIVATE(Q), point);
mbedtls_ecp_group_load(&mbedtls_pk_ec(*key)->MBEDTLS_PRIVATE(grp), ecp_grp->id);
pkey = (struct crypto_ec_key *)key;
crypto_ec_point_deinit((struct crypto_ec_point *)point, 0);
return pkey;
fail:
if (point) {
crypto_ec_point_deinit((struct crypto_ec_point *)point, 0);
}
if (key) {
mbedtls_pk_free(key);
}
pkey = NULL;
return pkey;
}
struct crypto_ec_point *crypto_ec_key_get_public_key(struct crypto_ec_key *key)
{
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
return (struct crypto_ec_point *)&mbedtls_pk_ec(*pkey)->MBEDTLS_PRIVATE(Q);
}
int crypto_ec_get_priv_key_der(struct crypto_ec_key *key, unsigned char **key_data, int *key_len)
{
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
char *der_data = os_malloc(ECP_PRV_DER_MAX_BYTES);
if (!der_data) {
wpa_printf(MSG_ERROR, "memory allocation failed");
return -1;
}
*key_len = mbedtls_pk_write_key_der(pkey, (unsigned char *)der_data, ECP_PRV_DER_MAX_BYTES);
if (*key_len <= 0) {
wpa_printf(MSG_ERROR, "Failed to write priv key");
os_free(der_data);
return -1;
}
*key_data = os_malloc(*key_len);
if (!*key_data) {
wpa_printf(MSG_ERROR, "memory allocation failed");
os_free(der_data);
return -1;
}
os_memcpy(*key_data, der_data + ECP_PRV_DER_MAX_BYTES - *key_len, *key_len);
os_free(der_data);
return 0;
}
struct crypto_ec_group *crypto_ec_get_group_from_key(struct crypto_ec_key *key)
{
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
return (struct crypto_ec_group *) & (mbedtls_pk_ec(*pkey)->MBEDTLS_PRIVATE(grp));
}
int crypto_ec_key_group(struct crypto_ec_key *key)
{
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
int iana_group = (int)crypto_ec_get_mbedtls_to_nist_group_id(mbedtls_pk_ec(*pkey)->MBEDTLS_PRIVATE(grp).id);
return iana_group;
}
struct crypto_bignum *crypto_ec_key_get_private_key(struct crypto_ec_key *key)
{
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
return ((struct crypto_bignum *) & (mbedtls_pk_ec(*pkey)->MBEDTLS_PRIVATE(d)));
}
int crypto_ec_get_publickey_buf(struct crypto_ec_key *key, u8 *key_buf, int len)
{
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE + 10]; /* tag, length + MPI */
unsigned char *c = buf + sizeof(buf);
int pk_len = 0;
memset(buf, 0, sizeof(buf));
pk_len = mbedtls_pk_write_pubkey(&c, buf, pkey);
if (pk_len < 0) {
return -1;
}
if (len == 0) {
return pk_len;
}
os_memcpy(key_buf, buf + MBEDTLS_MPI_MAX_SIZE + 10 - pk_len, pk_len);
return pk_len;
}
int crypto_write_pubkey_der(struct crypto_ec_key *key, unsigned char **key_buf)
{
unsigned char *buf = os_malloc(ECP_PUB_DER_MAX_BYTES);
if (!buf) {
wpa_printf(MSG_ERROR, "memory allocation failed");
return -1;
}
int len = mbedtls_pk_write_pubkey_der((mbedtls_pk_context *)key, buf, ECP_PUB_DER_MAX_BYTES);
if (len <= 0) {
os_free(buf);
return -1;
}
*key_buf = os_malloc(len);
if (!*key_buf) {
os_free(buf);
return -1;
}
os_memcpy(*key_buf, buf + ECP_PUB_DER_MAX_BYTES - len, len);
os_free(buf);
return len;
}
struct crypto_ec_key *crypto_ec_key_parse_priv(const u8 *privkey, size_t privkey_len)
{
int ret;
mbedtls_pk_context *kctx = (mbedtls_pk_context *)crypto_alloc_key();
if (!kctx) {
wpa_printf(MSG_ERROR, "memory allocation failed");
return NULL;
}
ret = mbedtls_pk_parse_key(kctx, privkey, privkey_len, NULL, 0, crypto_rng_wrapper, NULL);
if (ret < 0) {
//crypto_print_error_string(ret);
goto fail;
}
return (struct crypto_ec_key *)kctx;
fail:
mbedtls_pk_free(kctx);
os_free(kctx);
return NULL;
}
unsigned int crypto_ec_get_mbedtls_to_nist_group_id(int id)
{
unsigned int nist_grpid = 0;
switch (id) {
case MBEDTLS_ECP_DP_SECP256R1:
nist_grpid = 19;
break;
case MBEDTLS_ECP_DP_SECP384R1:
nist_grpid = 20;
break;
case MBEDTLS_ECP_DP_SECP521R1:
nist_grpid = 21;
break;
case MBEDTLS_ECP_DP_BP256R1:
nist_grpid = 28;
break;
case MBEDTLS_ECP_DP_BP384R1:
nist_grpid = 29;
break;
case MBEDTLS_ECP_DP_BP512R1:
nist_grpid = 30;
break;
default:
break;
}
return nist_grpid;
}
int crypto_ec_get_curve_id(const struct crypto_ec_group *group)
{
mbedtls_ecp_group *grp = (mbedtls_ecp_group *)group;
return (crypto_ec_get_mbedtls_to_nist_group_id(grp->id));
}
int crypto_ecdh(struct crypto_ec_key *key_own, struct crypto_ec_key *key_peer,
u8 *secret, size_t *secret_len)
{
mbedtls_ecdh_context *ctx = NULL;
mbedtls_pk_context *own = (mbedtls_pk_context *)key_own;
mbedtls_pk_context *peer = (mbedtls_pk_context *)key_peer;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
int ret = -1;
mbedtls_entropy_init(&entropy);
mbedtls_ctr_drbg_init(&ctr_drbg);
if (mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0) < 0) {
goto fail;
}
*secret_len = 0;
ctx = os_malloc(sizeof(*ctx));
if (!ctx) {
wpa_printf(MSG_ERROR, "DPP: EVP_PKEY_CTX_new failed: %s",
__func__);
goto fail;
}
mbedtls_ecdh_init(ctx);
/* No need to setup, done through mbedtls_ecdh_get_params */
/* set params from our key */
if (mbedtls_ecdh_get_params(ctx, mbedtls_pk_ec(*own), MBEDTLS_ECDH_OURS) < 0) {
wpa_printf(MSG_ERROR, "failed to set our ecdh params");
goto fail;
}
#ifndef DPP_MAX_SHARED_SECRET_LEN
#define DPP_MAX_SHARED_SECRET_LEN 66
#endif
/* set params from peers key */
if (mbedtls_ecdh_get_params(ctx, mbedtls_pk_ec(*peer), MBEDTLS_ECDH_THEIRS) < 0) {
wpa_printf(MSG_ERROR, "failed to set peer's ecdh params");
goto fail;
}
if (mbedtls_ecdh_calc_secret(ctx, secret_len, secret, DPP_MAX_SHARED_SECRET_LEN,
mbedtls_ctr_drbg_random, &ctr_drbg) < 0) {
wpa_printf(MSG_ERROR, "failed to calculate secret");
goto fail;
}
if (*secret_len > DPP_MAX_SHARED_SECRET_LEN) {
wpa_printf(MSG_ERROR, "secret len=%d is too big", *secret_len);
goto fail;
}
ret = 0;
fail:
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
if (ctx) {
mbedtls_ecdh_free(ctx);
os_free(ctx);
}
return ret;
}
int crypto_ecdsa_get_sign(unsigned char *hash,
const struct crypto_bignum *r, const struct crypto_bignum *s, struct crypto_ec_key *csign, int hash_len)
{
int ret = -1;
mbedtls_pk_context *pkey = (mbedtls_pk_context *)csign;
mbedtls_ecdsa_context *ctx = os_malloc(sizeof(*ctx));
if (!ctx) {
wpa_printf(MSG_ERROR, "failed to allcate memory");
return -1;
}
mbedtls_ecdsa_init(ctx);
if (mbedtls_ecdsa_from_keypair(ctx, mbedtls_pk_ec(*pkey)) < 0) {
goto fail;
}
ret = mbedtls_ecdsa_sign(&ctx->MBEDTLS_PRIVATE(grp), (mbedtls_mpi *)r, (mbedtls_mpi *)s,
&ctx->MBEDTLS_PRIVATE(d), hash, SHA256_MAC_LEN, crypto_rng_wrapper, NULL);
fail:
mbedtls_ecdsa_free(ctx);
os_free(ctx);
return ret;
}
int crypto_ec_key_verify_signature_r_s(struct crypto_ec_key *csign,
const unsigned char *hash, int hlen,
const u8 *r, size_t r_len,
const u8 *s, size_t s_len)
{
/* (mbedtls_ecdsa_context *) */
mbedtls_ecp_keypair *ecp_kp = mbedtls_pk_ec(*(mbedtls_pk_context *)csign);
if (!ecp_kp) {
return -1;
}
struct crypto_bignum *rb = NULL, *sb = NULL;
rb = crypto_bignum_init_set(r, r_len);
sb = crypto_bignum_init_set(s, s_len);
mbedtls_ecp_group *ecp_kp_grp = &ecp_kp->MBEDTLS_PRIVATE(grp);
mbedtls_ecp_point *ecp_kp_q = &ecp_kp->MBEDTLS_PRIVATE(Q);
int ret = mbedtls_ecdsa_verify(ecp_kp_grp, hash, hlen,
ecp_kp_q, (mbedtls_mpi *)rb, (mbedtls_mpi *)sb);
if (ret != 0) {
wpa_printf(MSG_ERROR, "ecdsa verification failed");
crypto_bignum_deinit(rb, 0);
crypto_bignum_deinit(sb, 0);
return ret;
}
return ret;
}
void crypto_ec_key_debug_print(struct crypto_ec_key *key, const char *title)
{
#ifdef DEBUG_PRINT
mbedtls_pk_context *pkey = (mbedtls_pk_context *)key;
mbedtls_ecp_keypair *ecp = mbedtls_pk_ec(*pkey);
u8 x[32], y[32], d[32];
wpa_printf(MSG_INFO, "curve: %s",
mbedtls_ecp_curve_info_from_grp_id(ecp->MBEDTLS_PRIVATE(grp).id)->name);
int len = mbedtls_mpi_size((mbedtls_mpi *)crypto_ec_get_prime((struct crypto_ec *)crypto_ec_get_group_from_key(key)));
wpa_printf(MSG_INFO, "prime len is %d", len);
crypto_ec_point_to_bin((struct crypto_ec *)crypto_ec_get_group_from_key(key), crypto_ec_key_get_public_key(key), x, y);
crypto_bignum_to_bin(crypto_ec_key_get_private_key(key),
d, len, len);
wpa_hexdump(MSG_INFO, "Q_x:", x, 32);
wpa_hexdump(MSG_INFO, "Q_y:", y, 32);
wpa_hexdump(MSG_INFO, "d: ", d, 32);
#endif
}
struct crypto_ec_key *crypto_ec_parse_subpub_key(const unsigned char *p, size_t len)
{
int ret;
mbedtls_pk_context *pkey = (mbedtls_pk_context *)crypto_alloc_key();
if (!pkey) {
return NULL;
}
ret = mbedtls_pk_parse_subpubkey((unsigned char **)&p, p + len, pkey);
if (ret == 0) {
return (struct crypto_ec_key *)pkey;
}
mbedtls_pk_free(pkey);
os_free(pkey);
return NULL;
}
int crypto_is_ec_key(struct crypto_ec_key *key)
{
int ret = mbedtls_pk_can_do((mbedtls_pk_context *)key, MBEDTLS_PK_ECKEY);
return ret;
}
struct crypto_ec_key * crypto_ec_key_gen(u16 ike_group)
{
mbedtls_pk_context *kctx = (mbedtls_pk_context *)crypto_alloc_key();
if (!kctx) {
wpa_printf(MSG_ERROR, "%s: memory allocation failed", __func__);
return NULL;
}
if (mbedtls_pk_setup(kctx,
mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY)) != 0) {
goto fail;
}
mbedtls_ecp_gen_key(MBEDTLS_ECP_DP_SECP256R1, mbedtls_pk_ec(*kctx), //get this from argument
crypto_rng_wrapper, NULL);
return (struct crypto_ec_key *)kctx;
fail:
mbedtls_pk_free(kctx);
os_free(kctx);
return NULL;
}
/*
* ECParameters ::= CHOICE {
* namedCurve OBJECT IDENTIFIER
* }
*/
static int pk_write_ec_param(unsigned char **p, unsigned char *start,
mbedtls_ecp_keypair *ec)
{
int ret;
size_t len = 0;
const char *oid;
size_t oid_len;
if ((ret = mbedtls_oid_get_oid_by_ec_grp(ec->MBEDTLS_PRIVATE(grp).id, &oid, &oid_len)) != 0) {
return (ret);
}
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len));
return ((int) len);
}
static int pk_write_ec_pubkey_formatted(unsigned char **p, unsigned char *start,
mbedtls_ecp_keypair *ec, int format)
{
int ret;
size_t len = 0;
unsigned char buf[MBEDTLS_ECP_MAX_PT_LEN];
if ((ret = mbedtls_ecp_point_write_binary(&ec->MBEDTLS_PRIVATE(grp), &ec->MBEDTLS_PRIVATE(Q),
format,
&len, buf, sizeof(buf))) != 0) {
return (ret);
}
if (*p < start || (size_t)(*p - start) < len) {
return (MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);
}
*p -= len;
memcpy(*p, buf, len);
return ((int) len);
}
int mbedtls_pk_write_pubkey_formatted(unsigned char **p, unsigned char *start,
const mbedtls_pk_context *key, int format)
{
int ret;
size_t len = 0;
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_pubkey_formatted(p, start, mbedtls_pk_ec(*key), format));
} else {
return (MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE);
}
return ((int) len);
}
int crypto_pk_write_formatted_pubkey_der(mbedtls_pk_context *key, unsigned char *buf, size_t size, int format)
{
int ret;
unsigned char *c;
size_t len = 0, par_len = 0, oid_len;
const char *oid;
if (size == 0) {
return (MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);
}
c = buf + size;
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_pk_write_pubkey_formatted(&c, buf, key, format));
if (c - buf < 1) {
return (MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);
}
/*
* SubjectPublicKeyInfo ::= SEQUENCE {
* algorithm AlgorithmIdentifier,
* subjectPublicKey BIT STRING }
*/
*--c = 0;
len += 1;
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_BIT_STRING));
if ((ret = mbedtls_oid_get_oid_by_pk_alg(mbedtls_pk_get_type(key),
&oid, &oid_len)) != 0) {
return (ret);
}
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(&c, buf, mbedtls_pk_ec(*key)));
}
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_algorithm_identifier(&c, buf, oid, oid_len,
par_len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
return ((int) len);
}
int crypto_ec_write_pub_key(struct crypto_ec_key *key, unsigned char **key_buf)
{
unsigned char output_buf[1600] = {0};
int len = crypto_pk_write_formatted_pubkey_der((mbedtls_pk_context *)key, output_buf, 1600, 1);
if (len <= 0) {
return 0;
}
*key_buf = os_malloc(len);
if (!*key_buf) {
wpa_printf(MSG_ERROR, "%s: memory allocation failed", __func__);
return 0;
}
os_memcpy(*key_buf, output_buf + 1600 - len, len);
return len;
}
struct wpabuf * crypto_ec_key_get_subject_public_key(struct crypto_ec_key *key)
{
unsigned char *der = NULL;
struct wpabuf *ret = NULL;
int der_len;
der_len = crypto_ec_write_pub_key(key, &der);
if (!der) {
wpa_printf(MSG_ERROR, "failed to get der for bootstrapping key\n");
return NULL;
}
ret = wpabuf_alloc_copy(der, der_len);
os_free(der);
return ret;
}
int crypto_mbedtls_get_grp_id(int group)
{
switch (group) {
case IANA_SECP256R1:
return MBEDTLS_ECP_DP_SECP256R1;
case IANA_SECP384R1:
return MBEDTLS_ECP_DP_SECP384R1;
case IANA_SECP521R1:
return MBEDTLS_ECP_DP_SECP521R1;
default:
return MBEDTLS_ECP_DP_NONE;
}
}
void crypto_ecdh_deinit(struct crypto_ecdh *ecdh)
{
mbedtls_ecdh_context *ctx = (mbedtls_ecdh_context *)ecdh;
if (!ctx) {
return;
}
mbedtls_ecdh_free(ctx);
os_free(ctx);
ctx = NULL;
}
struct crypto_ecdh * crypto_ecdh_init(int group)
{
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_entropy_context entropy;
mbedtls_ecdh_context *ctx;
ctx = os_zalloc(sizeof(*ctx));
if (!ctx) {
wpa_printf(MSG_ERROR, "Memory allocation failed for ecdh context");
goto fail;
}
mbedtls_ecdh_init(ctx);
#ifndef CONFIG_MBEDTLS_ECDH_LEGACY_CONTEXT
ctx->MBEDTLS_PRIVATE(var) = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
#endif
if ((mbedtls_ecp_group_load(ACCESS_ECDH(&ctx, grp), crypto_mbedtls_get_grp_id(group))) != 0) {
wpa_printf(MSG_ERROR, "Failed to set up ECDH context with group info");
goto fail;
}
/* Initialize CTR_DRBG context */
mbedtls_ctr_drbg_init(&ctr_drbg);
mbedtls_entropy_init(&entropy);
/* Seed and setup CTR_DRBG entropy source for future reseeds */
if (mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0) != 0) {
wpa_printf(MSG_ERROR, "Seeding entropy source failed");
goto fail;
}
/* Generates ECDH keypair on elliptic curve */
if (mbedtls_ecdh_gen_public(ACCESS_ECDH(&ctx, grp), ACCESS_ECDH(&ctx, d), ACCESS_ECDH(&ctx, Q), mbedtls_ctr_drbg_random, &ctr_drbg) != 0) {
wpa_printf(MSG_ERROR, "ECDH keypair on curve failed");
goto fail;
}
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
return (struct crypto_ecdh *)ctx;
fail:
if (ctx) {
mbedtls_ecdh_free(ctx);
os_free(ctx);
ctx = NULL;
}
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
return NULL;
}
struct wpabuf * crypto_ecdh_get_pubkey(struct crypto_ecdh *ecdh, int y)
{
struct wpabuf *public_key = NULL;
uint8_t *buf = NULL;
mbedtls_ecdh_context *ctx = (mbedtls_ecdh_context *)ecdh;
size_t prime_len = ACCESS_ECDH(ctx, grp).pbits / 8;
buf = os_zalloc(y ? prime_len : 2 * prime_len);
if (!buf) {
wpa_printf(MSG_ERROR, "Memory allocation failed");
return NULL;
}
/* Export an MPI into unsigned big endian binary data of fixed size */
mbedtls_mpi_write_binary(ACCESS_ECDH(&ctx, Q).MBEDTLS_PRIVATE(X), buf, prime_len);
public_key = wpabuf_alloc_copy(buf, 32);
os_free(buf);
return public_key;
}
struct wpabuf * crypto_ecdh_set_peerkey(struct crypto_ecdh *ecdh, int inc_y,
const u8 *key, size_t len)
{
uint8_t *secret = 0;
size_t olen = 0, len_prime = 0;
struct crypto_bignum *bn_x = NULL;
struct crypto_ec_point *ec_pt = NULL;
uint8_t *px = NULL, *py = NULL, *buf = NULL;
struct crypto_ec_key *pkey = NULL;
struct wpabuf *sh_secret = NULL;
int secret_key = 0;
mbedtls_ecdh_context *ctx = (mbedtls_ecdh_context *)ecdh;
if (!ctx) {
wpa_printf(MSG_ERROR, "ECDH Context is NULL");
return 0;
}
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_entropy_context entropy;
/* Initialize CTR_DRBG context */
mbedtls_ctr_drbg_init(&ctr_drbg);
mbedtls_entropy_init(&entropy);
/* Seed and setup CTR_DRBG entropy source for future reseeds */
if (mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0) != 0) {
wpa_printf(MSG_ERROR, "Seeding entropy source failed");
goto cleanup;
}
len_prime = ACCESS_ECDH(ctx, grp).pbits / 8;
bn_x = crypto_bignum_init_set(key, len);
/* Initialize data for EC point */
ec_pt = crypto_ec_point_init((struct crypto_ec*)ACCESS_ECDH(&ctx, grp));
if (!ec_pt) {
wpa_printf(MSG_ERROR, "Initializing for EC point failed");
goto cleanup;
}
if (crypto_ec_point_solve_y_coord((struct crypto_ec *)ACCESS_ECDH(&ctx, grp), ec_pt, bn_x, inc_y) != 0) {
wpa_printf(MSG_ERROR, "Failed to solve for y coordinate");
goto cleanup;
}
px = os_zalloc(len);
py = os_zalloc(len);
buf = os_zalloc(2 * len);
if (!px || !py || !buf) {
wpa_printf(MSG_ERROR, "Memory allocation failed");
goto cleanup;
}
if (crypto_ec_point_to_bin((struct crypto_ec *)ACCESS_ECDH(&ctx, grp), ec_pt, px, py) != 0) {
wpa_printf(MSG_ERROR, "Failed to write EC point value as binary data");
goto cleanup;
}
os_memcpy(buf, px, len);
os_memcpy(buf + len, py, len);
pkey = crypto_ec_key_set_pub((struct crypto_ec_group*)ACCESS_ECDH(&ctx, grp), buf, len);
if (!pkey) {
wpa_printf(MSG_ERROR, "Failed to set point for peer's public key");
goto cleanup;
}
mbedtls_pk_context *peer = (mbedtls_pk_context*)pkey;
/* Setup ECDH context from EC key */
/* Call to mbedtls_ecdh_get_params() will initialize the context when not LEGACY context */
if (peer != NULL) {
mbedtls_ecp_copy(ACCESS_ECDH(&ctx, Qp), &(mbedtls_pk_ec(*peer))->MBEDTLS_PRIVATE(Q));
#ifndef CONFIG_MBEDTLS_ECDH_LEGACY_CONTEXT
ctx->MBEDTLS_PRIVATE(var) = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
#endif
} else {
wpa_printf(MSG_ERROR, "Failed to set peer's ECDH context");
goto cleanup;
}
int len_secret = inc_y ? 2 * len : len;
secret = os_zalloc(len_secret);
if (!secret) {
wpa_printf(MSG_ERROR, "Allocation failed for secret");
goto cleanup;
}
/* Calculate secret
z = F(DH(x,Y)) */
secret_key = mbedtls_ecdh_calc_secret(ctx, &olen, secret, len_prime, mbedtls_ctr_drbg_random, &ctr_drbg);
if (secret_key != 0) {
wpa_printf(MSG_ERROR, "Calculation of secret failed");
goto cleanup;
}
sh_secret = wpabuf_alloc_copy(secret, len_secret);
cleanup:
os_free(px);
os_free(py);
os_free(buf);
os_free(secret);
crypto_ec_key_deinit(pkey);
crypto_bignum_deinit(bn_x, 1);
crypto_ec_point_deinit(ec_pt, 1);
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
return sh_secret;
}
struct crypto_ec_key *crypto_ec_key_parse_pub(const u8 *der, size_t der_len)
{
int ret;
mbedtls_pk_context *pkey = os_zalloc(sizeof(*pkey));
if (!pkey) {
return NULL;
}
mbedtls_pk_init(pkey);
ret = mbedtls_pk_parse_public_key(pkey, der, der_len);
if (ret < 0) {
wpa_printf(MSG_ERROR, "failed to parse ec public key");
os_free(pkey);
return NULL;
}
return (struct crypto_ec_key *)pkey;
}
void crypto_ec_key_deinit(struct crypto_ec_key *key)
{
mbedtls_pk_free((mbedtls_pk_context *)key);
os_free(key);
}
int crypto_ec_key_verify_signature(struct crypto_ec_key *key, const u8 *data,
size_t len, const u8 *sig, size_t sig_len)
{
int ret = 0;
mbedtls_ecdsa_context *ctx_verify = os_malloc(sizeof(mbedtls_ecdsa_context));
if (!ctx_verify) {
return -1;
}
mbedtls_ecdsa_init(ctx_verify);
mbedtls_ecp_keypair *ec_key = mbedtls_pk_ec(*((mbedtls_pk_context *)key));
mbedtls_ecp_group *grp = &ec_key->MBEDTLS_PRIVATE(grp);
if ((ret = mbedtls_ecp_group_copy(&ctx_verify->MBEDTLS_PRIVATE(grp), grp)) != 0) {
goto cleanup;
}
if ((ret = mbedtls_ecp_copy(&ctx_verify->MBEDTLS_PRIVATE(Q), &ec_key->MBEDTLS_PRIVATE(Q))) != 0) {
goto cleanup;
}
if ((ret = mbedtls_ecdsa_read_signature(ctx_verify,
data, len,
sig, sig_len)) != 0) {
goto cleanup;
}
ret = 1;
cleanup:
mbedtls_ecdsa_free(ctx_verify);
os_free(ctx_verify);
return ret;
}
#endif /* CONFIG_ECC */
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