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/*
* ECC setters for PK.
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "common.h"
#include "mbedtls/pk.h"
#include "mbedtls/error.h"
#include "mbedtls/ecp.h"
#include "pk_internal.h"
#if defined(MBEDTLS_PK_C) && defined(MBEDTLS_PK_HAVE_ECC_KEYS)
int mbedtls_pk_ecc_set_group(mbedtls_pk_context *pk, mbedtls_ecp_group_id grp_id)
{
#if defined(MBEDTLS_PK_USE_PSA_EC_DATA)
size_t ec_bits;
psa_ecc_family_t ec_family = mbedtls_ecc_group_to_psa(grp_id, &ec_bits);
/* group may already be initialized; if so, make sure IDs match */
if ((pk->ec_family != 0 && pk->ec_family != ec_family) ||
(pk->ec_bits != 0 && pk->ec_bits != ec_bits)) {
return MBEDTLS_ERR_PK_KEY_INVALID_FORMAT;
}
/* set group */
pk->ec_family = ec_family;
pk->ec_bits = ec_bits;
return 0;
#else /* MBEDTLS_PK_USE_PSA_EC_DATA */
mbedtls_ecp_keypair *ecp = mbedtls_pk_ec_rw(*pk);
/* grp may already be initialized; if so, make sure IDs match */
if (mbedtls_pk_ec_ro(*pk)->grp.id != MBEDTLS_ECP_DP_NONE &&
mbedtls_pk_ec_ro(*pk)->grp.id != grp_id) {
return MBEDTLS_ERR_PK_KEY_INVALID_FORMAT;
}
/* set group */
return mbedtls_ecp_group_load(&(ecp->grp), grp_id);
#endif /* MBEDTLS_PK_USE_PSA_EC_DATA */
}
int mbedtls_pk_ecc_set_key(mbedtls_pk_context *pk, unsigned char *key, size_t key_len)
{
#if defined(MBEDTLS_PK_USE_PSA_EC_DATA)
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_key_usage_t flags;
psa_status_t status;
psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(pk->ec_family));
if (pk->ec_family == PSA_ECC_FAMILY_MONTGOMERY) {
/* Do not set algorithm here because Montgomery keys cannot do ECDSA and
* the PK module cannot do ECDH. When the key will be used in TLS for
* ECDH, it will be exported and then re-imported with proper flags
* and algorithm. */
flags = PSA_KEY_USAGE_EXPORT;
} else {
psa_set_key_algorithm(&attributes,
MBEDTLS_PK_PSA_ALG_ECDSA_MAYBE_DET(PSA_ALG_ANY_HASH));
flags = PSA_KEY_USAGE_SIGN_HASH | PSA_KEY_USAGE_SIGN_MESSAGE |
PSA_KEY_USAGE_EXPORT;
}
psa_set_key_usage_flags(&attributes, flags);
status = psa_import_key(&attributes, key, key_len, &pk->priv_id);
return psa_pk_status_to_mbedtls(status);
#else /* MBEDTLS_PK_USE_PSA_EC_DATA */
mbedtls_ecp_keypair *eck = mbedtls_pk_ec_rw(*pk);
int ret = mbedtls_ecp_read_key(eck->grp.id, eck, key, key_len);
if (ret != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret);
}
return 0;
#endif /* MBEDTLS_PK_USE_PSA_EC_DATA */
}
int mbedtls_pk_ecc_set_pubkey_from_prv(mbedtls_pk_context *pk,
const unsigned char *prv, size_t prv_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng)
{
#if defined(MBEDTLS_PK_USE_PSA_EC_DATA)
(void) f_rng;
(void) p_rng;
(void) prv;
(void) prv_len;
psa_status_t status;
status = psa_export_public_key(pk->priv_id, pk->pub_raw, sizeof(pk->pub_raw),
&pk->pub_raw_len);
return psa_pk_status_to_mbedtls(status);
#elif defined(MBEDTLS_USE_PSA_CRYPTO) /* && !MBEDTLS_PK_USE_PSA_EC_DATA */
(void) f_rng;
(void) p_rng;
psa_status_t status;
mbedtls_ecp_keypair *eck = (mbedtls_ecp_keypair *) pk->pk_ctx;
size_t curve_bits;
psa_ecc_family_t curve = mbedtls_ecc_group_to_psa(eck->grp.id, &curve_bits);
/* Import private key into PSA, from serialized input */
mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
psa_key_attributes_t key_attr = PSA_KEY_ATTRIBUTES_INIT;
psa_set_key_type(&key_attr, PSA_KEY_TYPE_ECC_KEY_PAIR(curve));
psa_set_key_usage_flags(&key_attr, PSA_KEY_USAGE_EXPORT);
status = psa_import_key(&key_attr, prv, prv_len, &key_id);
if (status != PSA_SUCCESS) {
return psa_pk_status_to_mbedtls(status);
}
/* Export public key from PSA */
unsigned char pub[MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH];
size_t pub_len;
status = psa_export_public_key(key_id, pub, sizeof(pub), &pub_len);
psa_status_t destruction_status = psa_destroy_key(key_id);
if (status != PSA_SUCCESS) {
return psa_pk_status_to_mbedtls(status);
} else if (destruction_status != PSA_SUCCESS) {
return psa_pk_status_to_mbedtls(destruction_status);
}
/* Load serialized public key into ecp_keypair structure */
return mbedtls_ecp_point_read_binary(&eck->grp, &eck->Q, pub, pub_len);
#else /* MBEDTLS_USE_PSA_CRYPTO */
(void) prv;
(void) prv_len;
mbedtls_ecp_keypair *eck = (mbedtls_ecp_keypair *) pk->pk_ctx;
return mbedtls_ecp_mul(&eck->grp, &eck->Q, &eck->d, &eck->grp.G, f_rng, p_rng);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
}
#if defined(MBEDTLS_PK_USE_PSA_EC_DATA)
/*
* Set the public key: fallback using ECP_LIGHT in the USE_PSA_EC_DATA case.
*
* Normally, when MBEDTLS_PK_USE_PSA_EC_DATA is enabled, we only use PSA
* functions to handle keys. However, currently psa_import_key() does not
* support compressed points. In case that support was explicitly requested,
* this fallback uses ECP functions to get the job done. This is the reason
* why MBEDTLS_PK_PARSE_EC_COMPRESSED auto-enables MBEDTLS_ECP_LIGHT.
*
* [in/out] pk: in: must have the group set, see mbedtls_pk_ecc_set_group().
* out: will have the public key set.
* [in] pub, pub_len: the public key as an ECPoint,
* in any format supported by ECP.
*
* Return:
* - 0 on success;
* - MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the format is potentially valid
* but not supported;
* - another error code otherwise.
*/
static int pk_ecc_set_pubkey_psa_ecp_fallback(mbedtls_pk_context *pk,
const unsigned char *pub,
size_t pub_len)
{
#if !defined(MBEDTLS_PK_PARSE_EC_COMPRESSED)
(void) pk;
(void) pub;
(void) pub_len;
return MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
#else /* MBEDTLS_PK_PARSE_EC_COMPRESSED */
mbedtls_ecp_keypair ecp_key;
mbedtls_ecp_group_id ecp_group_id;
int ret;
ecp_group_id = mbedtls_ecc_group_from_psa(pk->ec_family, pk->ec_bits);
mbedtls_ecp_keypair_init(&ecp_key);
ret = mbedtls_ecp_group_load(&(ecp_key.grp), ecp_group_id);
if (ret != 0) {
goto exit;
}
ret = mbedtls_ecp_point_read_binary(&(ecp_key.grp), &ecp_key.Q,
pub, pub_len);
if (ret != 0) {
goto exit;
}
ret = mbedtls_ecp_point_write_binary(&(ecp_key.grp), &ecp_key.Q,
MBEDTLS_ECP_PF_UNCOMPRESSED,
&pk->pub_raw_len, pk->pub_raw,
sizeof(pk->pub_raw));
exit:
mbedtls_ecp_keypair_free(&ecp_key);
return ret;
#endif /* MBEDTLS_PK_PARSE_EC_COMPRESSED */
}
#endif /* MBEDTLS_PK_USE_PSA_EC_DATA */
int mbedtls_pk_ecc_set_pubkey(mbedtls_pk_context *pk, const unsigned char *pub, size_t pub_len)
{
#if defined(MBEDTLS_PK_USE_PSA_EC_DATA)
/* Load the key */
if (!PSA_ECC_FAMILY_IS_WEIERSTRASS(pk->ec_family) || *pub == 0x04) {
/* Format directly supported by PSA:
* - non-Weierstrass curves that only have one format;
* - uncompressed format for Weierstrass curves. */
if (pub_len > sizeof(pk->pub_raw)) {
return MBEDTLS_ERR_PK_BUFFER_TOO_SMALL;
}
memcpy(pk->pub_raw, pub, pub_len);
pk->pub_raw_len = pub_len;
} else {
/* Other format, try the fallback */
int ret = pk_ecc_set_pubkey_psa_ecp_fallback(pk, pub, pub_len);
if (ret != 0) {
return ret;
}
}
/* Validate the key by trying to import it */
mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
psa_key_attributes_t key_attrs = PSA_KEY_ATTRIBUTES_INIT;
psa_set_key_usage_flags(&key_attrs, 0);
psa_set_key_type(&key_attrs, PSA_KEY_TYPE_ECC_PUBLIC_KEY(pk->ec_family));
psa_set_key_bits(&key_attrs, pk->ec_bits);
if ((psa_import_key(&key_attrs, pk->pub_raw, pk->pub_raw_len,
&key_id) != PSA_SUCCESS) ||
(psa_destroy_key(key_id) != PSA_SUCCESS)) {
return MBEDTLS_ERR_PK_INVALID_PUBKEY;
}
return 0;
#else /* MBEDTLS_PK_USE_PSA_EC_DATA */
int ret;
mbedtls_ecp_keypair *ec_key = (mbedtls_ecp_keypair *) pk->pk_ctx;
ret = mbedtls_ecp_point_read_binary(&ec_key->grp, &ec_key->Q, pub, pub_len);
if (ret != 0) {
return ret;
}
return mbedtls_ecp_check_pubkey(&ec_key->grp, &ec_key->Q);
#endif /* MBEDTLS_PK_USE_PSA_EC_DATA */
}
#endif /* MBEDTLS_PK_C && MBEDTLS_PK_HAVE_ECC_KEYS */
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