/** * Copyright (c) 2018, Nordic Semiconductor ASA * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * 2. Redistributions in binary form, except as embedded into a Nordic * Semiconductor ASA integrated circuit in a product or a software update for * such product, must reproduce the above copyright notice, this list of * conditions and the following disclaimer in the documentation and/or other * materials provided with the distribution. * * 3. Neither the name of Nordic Semiconductor ASA nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * 4. This software, with or without modification, must only be used with a * Nordic Semiconductor ASA integrated circuit. * * 5. Any software provided in binary form under this license must not be reverse * engineered, decompiled, modified and/or disassembled. * * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ #include "sdk_common.h" #if NRF_MODULE_ENABLED(NRF_BLE_LESC) #include "nrf_ble_lesc.h" #include "nrf_crypto.h" #define NRF_LOG_MODULE_NAME nrf_ble_lesc #include "nrf_log.h" NRF_LOG_MODULE_REGISTER(); /**@brief Descriptor of the peer public key. */ typedef struct { nrf_crypto_ecc_public_key_t value; /**< Peer public key. */ volatile bool is_valid; /**< Flag indicating that the public key is valid. */ } nrf_ble_lesc_peer_pub_key_t; /**@brief The maximum number of peripheral and central connections combined. * This value is based on what is configured in the SoftDevice handler sdk_config. */ #define NRF_BLE_LESC_LINK_COUNT (NRF_SDH_BLE_PERIPHERAL_LINK_COUNT + NRF_SDH_BLE_CENTRAL_LINK_COUNT) __ALIGN(4) static ble_gap_lesc_p256_pk_t m_lesc_public_key; /**< LESC ECC Public Key. */ __ALIGN(4) static ble_gap_lesc_dhkey_t m_lesc_dh_key; /**< LESC ECC DH Key. */ static nrf_crypto_ecdh_context_t m_ecdh_context; /**< Context to do the LESC ECDH calculation */ static bool m_ble_lesc_internal_error; /**< Flag indicating that the module encountered an internal error. */ static bool m_keypair_generated; /**< Flag indicating that the local ECDH key pair was generated. */ static nrf_crypto_ecc_key_pair_generate_context_t m_keygen_context; /**< Context to generate private/public key pair. */ static nrf_crypto_ecc_private_key_t m_private_key; /**< Allocated private key type to use for LESC DH generation. */ static nrf_crypto_ecc_public_key_t m_public_key; /**< Allocated public key type to use for LESC DH generation. */ static nrf_ble_lesc_peer_pub_key_t m_peer_keys[NRF_BLE_LESC_LINK_COUNT]; /**< Array of pointers to peer public keys, used for LESC DH generation. */ ret_code_t nrf_ble_lesc_init(void) { ret_code_t err_code; memset((void *) m_peer_keys, 0, sizeof(m_peer_keys)); #if NRF_CRYPTO_ALLOCATOR == NRF_CRYPTO_ALLOCATOR_NRF_MALLOC // Initialize mem_manager if used by nrf_crypto. err_code = nrf_mem_init(); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_mem_init() returned error 0x%x.", err_code); return err_code; } #endif // Ensure that nrf_crypto has been initialized. err_code = nrf_crypto_init(); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_init() returned error 0x%x.", err_code); return err_code; } NRF_LOG_DEBUG("Initialized nrf_crypto."); #if defined(NRF_CRYPTO_RNG_AUTO_INIT_ENABLED) && (NRF_CRYPTO_RNG_AUTO_INIT_ENABLED == 1) // Do nothing. RNG is initialized with nrf_crypto_init call. #elif defined((NRF_CRYPTO_RNG_AUTO_INIT_ENABLED) && (NRF_CRYPTO_RNG_AUTO_INIT_ENABLED == 0) // Initialize the RNG. err_code = nrf_crypto_rng_init(NULL, NULL); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_rng_init() returned error 0x%x.", err_code); return err_code; } #else #error Invalid sdk_config.h (does not contain NRF_CRYPTO_RNG_AUTO_INIT_ENABLED) #endif // defined(NRF_CRYPTO_RNG_AUTO_INIT_ENABLED) && (NRF_CRYPTO_RNG_AUTO_INIT_ENABLED == 1) NRF_LOG_DEBUG("Initialized nrf_ble_lesc."); // Reset module state. m_ble_lesc_internal_error = false; m_keypair_generated = false; // Generate ECC key pair. Only one key pair is automatically generated by this module. err_code = nrf_ble_lesc_keypair_generate(); return err_code; } ret_code_t nrf_ble_lesc_keypair_generate(void) { ret_code_t err_code; size_t public_len = NRF_CRYPTO_ECC_SECP256R1_RAW_PUBLIC_KEY_SIZE; // Check if any DH computation is pending for (uint32_t i = 0; i < ARRAY_SIZE(m_peer_keys); i++) { if (m_peer_keys[i].is_valid) { return NRF_ERROR_BUSY; } } // Update flag to indicate that there is no valid private key. m_keypair_generated = false; NRF_LOG_DEBUG("Generating ECC key pair"); err_code = nrf_crypto_ecc_key_pair_generate(&m_keygen_context, &g_nrf_crypto_ecc_secp256r1_curve_info, &m_private_key, &m_public_key); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_ecc_key_pair_generate() returned error 0x%x.", err_code); return err_code; } // Convert to a raw type. err_code = nrf_crypto_ecc_public_key_to_raw(&m_public_key, m_lesc_public_key.pk, &public_len); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_ecc_public_key_to_raw() returned error 0x%x.", err_code); return err_code; } // Invert the raw type to little-endian (required for BLE). err_code = nrf_crypto_ecc_byte_order_invert(&g_nrf_crypto_ecc_secp256r1_curve_info, m_lesc_public_key.pk, m_lesc_public_key.pk, NRF_CRYPTO_ECC_SECP256R1_RAW_PUBLIC_KEY_SIZE); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_ecc_byte_order_invert() returned error 0x%x.", err_code); } else { // Set the flag to indicate that there is a valid ECDH key pair generated. m_keypair_generated = true; } return err_code; } ble_gap_lesc_p256_pk_t * nrf_ble_lesc_public_key_get(void) { ble_gap_lesc_p256_pk_t * p_lesc_pk = NULL; if (m_keypair_generated) { p_lesc_pk = &m_lesc_public_key; } else { NRF_LOG_ERROR("Trying to access LESC public key that has not been generated yet."); } return p_lesc_pk; } /**@brief Function for calculating a DH key and responding to the DH key request on a given * connection handle. * * @param[in] p_peer_public_key ECC peer public key, used to compute shared secret. * @param[in] conn_handle Connection handle. * * @retval NRF_SUCCESS If the operation was successful. * @retval Other Other error codes might be returned by the @ref nrf_crypto_ecdh_compute, @ref * nrf_crypto_ecc_byte_order_invert, and @ref sd_ble_gap_lesc_dhkey_reply functions. */ static ret_code_t compute_and_give_dhkey(nrf_ble_lesc_peer_pub_key_t * p_peer_public_key, uint16_t conn_handle) { ret_code_t err_code = NRF_ERROR_INTERNAL; size_t shared_secret_size = BLE_GAP_LESC_DHKEY_LEN; uint8_t * p_shared_secret = m_lesc_dh_key.key; // Check if there is a valid generated and set a local ECDH public key. if (!m_keypair_generated) { return NRF_ERROR_INTERNAL; } // Check if the public_key is valid if (p_peer_public_key->is_valid) { err_code = nrf_crypto_ecdh_compute(&m_ecdh_context, &m_private_key, &p_peer_public_key->value, p_shared_secret, &shared_secret_size); } if (err_code == NRF_SUCCESS) { // Invert the shared secret for little endian format. err_code = nrf_crypto_ecc_byte_order_invert(&g_nrf_crypto_ecc_secp256r1_curve_info, p_shared_secret, p_shared_secret, BLE_GAP_LESC_DHKEY_LEN); VERIFY_SUCCESS(err_code); } else { NRF_LOG_WARNING("Creating invalid shared secret to make LESC fail."); err_code = nrf_crypto_rng_vector_generate(p_shared_secret, BLE_GAP_LESC_DHKEY_LEN); VERIFY_SUCCESS(err_code); } NRF_LOG_INFO("Calling sd_ble_gap_lesc_dhkey_reply on conn_handle: %d", conn_handle); err_code = sd_ble_gap_lesc_dhkey_reply(conn_handle, &m_lesc_dh_key); return err_code; } ret_code_t nrf_ble_lesc_request_handler(void) { ret_code_t err_code = NRF_SUCCESS; // If the LESC module is in an invalid state, a restart is required. if (m_ble_lesc_internal_error) { return NRF_ERROR_INTERNAL; } for (uint16_t i = 0; i < NRF_BLE_LESC_LINK_COUNT; i++) { if (m_peer_keys[i].is_valid) { err_code = compute_and_give_dhkey(&m_peer_keys[i], i); m_peer_keys[i].is_valid = false; VERIFY_SUCCESS(err_code); } } return err_code; } /**@brief Function for handling a DH key request event. * * @param[in] conn_handle Connection handle. * @param[in] p_dhkey_request DH key request descriptor. * * @retval NRF_SUCCESS If the operation was successful. * @retval Other Other error codes might be returned by the @ref nrf_crypto_ecc_byte_order_invert * and @ref nrf_crypto_ecc_public_key_from_raw functions. */ static ret_code_t on_dhkey_request(uint16_t conn_handle, ble_gap_evt_lesc_dhkey_request_t const * p_dhkey_request) { ret_code_t err_code = NRF_SUCCESS; uint8_t public_raw[BLE_GAP_LESC_P256_PK_LEN]; uint8_t * p_public_raw; size_t public_raw_len; // Convert the received public key from big-endian to little endian. p_public_raw = p_dhkey_request->p_pk_peer->pk; public_raw_len = BLE_GAP_LESC_P256_PK_LEN; err_code = nrf_crypto_ecc_byte_order_invert(&g_nrf_crypto_ecc_secp256r1_curve_info, p_public_raw, public_raw, public_raw_len); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_ecc_byte_order_invert() returned error 0x%x.", err_code); return err_code; } // Copy peer public key to the allocated context. The dhkey calculation will be performed in // @ref nrf_ble_lesc_request_handler, so it does not block normal operation. err_code = nrf_crypto_ecc_public_key_from_raw(&g_nrf_crypto_ecc_secp256r1_curve_info, &m_peer_keys[conn_handle].value, public_raw, public_raw_len); if (err_code != NRF_SUCCESS) { NRF_LOG_ERROR("nrf_crypto_ecc_public_key_from_raw() returned error 0x%x.", err_code); m_peer_keys[conn_handle].is_valid = false; } else { m_peer_keys[conn_handle].is_valid = true; } return NRF_SUCCESS; } void nrf_ble_lesc_on_ble_evt(ble_evt_t const * p_ble_evt) { ret_code_t err_code = NRF_SUCCESS; uint16_t conn_handle = p_ble_evt->evt.gap_evt.conn_handle; switch (p_ble_evt->header.evt_id) { case BLE_GAP_EVT_DISCONNECTED: m_peer_keys[conn_handle].is_valid = false; break; case BLE_GAP_EVT_LESC_DHKEY_REQUEST: NRF_LOG_DEBUG("BLE_GAP_EVT_LESC_DHKEY_REQUEST"); err_code = on_dhkey_request(conn_handle, &p_ble_evt->evt.gap_evt.params.lesc_dhkey_request); if (err_code != NRF_SUCCESS) { m_ble_lesc_internal_error = true; } break; default: break; } } #endif // NRF_BLE_LESC_ENABLED