/* * Copyright (C) 2011-2012 BlueKitchen GmbH * * 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 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 the copyright holders nor the names of * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * 4. Any redistribution, use, or modification is done solely for * personal benefit and not for any commercial purpose or for * monetary gain. * * THIS SOFTWARE IS PROVIDED BY MATTHIAS RINGWALD AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS * RINGWALD 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. * * Please inquire about commercial licensing options at contact@bluekitchen-gmbh.com * */ #include #include #include "debug.h" #include "hci.h" #include "l2cap.h" #include "central_device_db.h" #include "sm.h" #include "gap_le.h" // // SM internal types and globals // typedef enum { SM_STATE_IDLE, SM_STATE_SEND_SECURITY_REQUEST, SM_STATE_SEND_LTK_REQUESTED_NEGATIVE_REPLY, // Phase 1: Pairing Feature Exchange SM_STATE_PH1_SEND_PAIRING_RESPONSE, SM_STATE_PH1_W4_PAIRING_CONFIRM, SM_STATE_PH1_W4_USER_RESPONSE, SM_STATE_SEND_PAIRING_FAILED, SM_STATE_SEND_PAIRING_RANDOM, // Phase 2: Authenticating and Encrypting // get random number for TK if we show it SM_STATE_PH2_GET_RANDOM_TK, SM_STATE_PH2_W4_RANDOM_TK, // calculate confirm values for local and remote connection SM_STATE_PH2_C1_GET_RANDOM_A, SM_STATE_PH2_C1_W4_RANDOM_A, SM_STATE_PH2_C1_GET_RANDOM_B, SM_STATE_PH2_C1_W4_RANDOM_B, SM_STATE_PH2_C1_GET_ENC_A, SM_STATE_PH2_C1_W4_ENC_A, SM_STATE_PH2_C1_GET_ENC_B, SM_STATE_PH2_C1_W4_ENC_B, SM_STATE_PH2_C1_SEND_PAIRING_CONFIRM, SM_STATE_PH2_W4_PAIRING_RANDOM, SM_STATE_PH2_C1_GET_ENC_C, SM_STATE_PH2_C1_W4_ENC_C, SM_STATE_PH2_C1_GET_ENC_D, SM_STATE_PH2_C1_W4_ENC_D, // calc STK SM_STATE_PH2_CALC_STK, SM_STATE_PH2_W4_STK, SM_STATE_PH2_SEND_STK, SM_STATE_PH2_W4_LTK_REQUEST, SM_STATE_PH2_W4_CONNECTION_ENCRYPTED, // Phase 3: Transport Specific Key Distribution // calculate DHK, Y, EDIV, and LTK SM_STATE_PH3_GET_RANDOM, SM_STATE_PH3_W4_RANDOM, SM_STATE_PH3_GET_DIV, SM_STATE_PH3_W4_DIV, SM_STATE_PH3_Y_GET_ENC, SM_STATE_PH3_Y_W4_ENC, SM_STATE_PH3_LTK_GET_ENC, SM_STATE_PH3_LTK_W4_ENC, // SM_STATE_DISTRIBUTE_KEYS, // re establish previously distribued LTK SM_STATE_PH4_Y_GET_ENC, SM_STATE_PH4_Y_W4_ENC, SM_STATE_PH4_LTK_GET_ENC, SM_STATE_PH4_LTK_W4_ENC, SM_STATE_PH4_SEND_LTK, SM_STATE_TIMEOUT, // no other security messages are exchanged } security_manager_state_t; typedef enum { DKG_W4_WORKING, DKG_CALC_IRK, DKG_W4_IRK, DKG_CALC_DHK, DKG_W4_DHK, DKG_READY } derived_key_generation_t; typedef enum { RAU_IDLE, RAU_GET_RANDOM, RAU_W4_RANDOM, RAU_GET_ENC, RAU_W4_ENC, RAU_SET_ADDRESS, } random_address_update_t; typedef enum { CMAC_IDLE, CMAC_CALC_SUBKEYS, CMAC_W4_SUBKEYS, CMAC_CALC_MI, CMAC_W4_MI, CMAC_CALC_MLAST, CMAC_W4_MLAST } cmac_state_t; typedef enum { JUST_WORKS, PK_RESP_INPUT, // Initiator displays PK, initiator inputs PK PK_INIT_INPUT, // Responder displays PK, responder inputs PK OK_BOTH_INPUT, // Only input on both, both input PK OOB // OOB available on both sides } stk_generation_method_t; typedef enum { SM_USER_RESPONSE_IDLE, SM_USER_RESPONSE_PENDING, SM_USER_RESPONSE_CONFIRM, SM_USER_RESPONSE_PASSKEY, SM_USER_RESPONSE_DECLINE } sm_user_response_t; // // GLOBAL DATA // // Security Manager Master Keys, please use sm_set_er(er) and sm_set_ir(ir) with your own 128 bit random values static sm_key_t sm_persistent_er; static sm_key_t sm_persistent_ir; // derived from sm_persistent_ir static sm_key_t sm_persistent_dhk; static sm_key_t sm_persistent_irk; // derived from sm_persistent_er // .. static uint8_t sm_accepted_stk_generation_methods; static uint8_t sm_max_encryption_key_size; static uint8_t sm_min_encryption_key_size; static uint8_t sm_s_auth_req = 0; static uint8_t sm_s_io_capabilities = IO_CAPABILITY_UNKNOWN; static uint8_t sm_s_request_security = 0; // static derived_key_generation_t dkg_state = DKG_W4_WORKING; // random address update static random_address_update_t rau_state = RAU_IDLE; static bd_addr_t sm_random_address; // resolvable private address lookup static int sm_central_device_test; static int sm_central_device_matched; static int sm_central_ah_calculation_active; // static uint8_t sm_s_addr_type; static bd_addr_t sm_s_address; static uint8_t sm_actual_encryption_key_size; static uint8_t sm_connection_encrypted; static uint8_t sm_connection_authenticated; // [0..1] static uint8_t sm_connection_authorization_state; // PER INSTANCE DATA static security_manager_state_t sm_state_responding = SM_STATE_IDLE; static uint16_t sm_response_handle = 0; static uint8_t sm_pairing_failed_reason = 0; // SM timeout static timer_source_t sm_timeout; // data to send to aes128 crypto engine, see sm_aes128_set_key and sm_aes128_set_plaintext static sm_key_t sm_aes128_key; static sm_key_t sm_aes128_plaintext; static uint8_t sm_aes128_active; // generation method and temporary key for STK - STK is stored in sm_s_ltk static stk_generation_method_t sm_stk_generation_method; static sm_key_t sm_tk; // user response static uint8_t sm_user_response; // defines which keys will be send after connection is encrypted static int sm_key_distribution_send_set; static int sm_key_distribution_received_set; // // Volume 3, Part H, Chapter 24 // "Security shall be initiated by the Security Manager in the device in the master role. // The device in the slave role shall be the responding device." // -> master := initiator, slave := responder // static uint8_t sm_m_io_capabilities; static uint8_t sm_m_have_oob_data; static uint8_t sm_m_auth_req; static uint8_t sm_m_max_encryption_key_size; static uint8_t sm_m_key_distribution; static uint8_t sm_m_preq[7]; static sm_key_t sm_m_random; static sm_key_t sm_m_confirm; static sm_key_t sm_s_random; static uint8_t sm_s_have_oob_data; static sm_key_t sm_s_confirm; static uint8_t sm_s_pres[7]; // key distribution, slave sends static sm_key_t sm_s_ltk; static uint16_t sm_s_y; static uint16_t sm_s_div; static uint16_t sm_s_ediv; static uint8_t sm_s_rand[8]; // commented keys are not used in Perihperal role // static sm_key_t sm_s_csrk; // key distribution, received from master // commented keys that are not stored or used by Peripheral role // static sm_key_t sm_m_ltk; // static uint16_t sm_m_ediv; // static uint8_t sm_m_rand[8]; static uint8_t sm_m_addr_type; static bd_addr_t sm_m_address; static sm_key_t sm_m_csrk; static sm_key_t sm_m_irk; // CMAC calculation - only used by signed writes static cmac_state_t sm_cmac_state; static sm_key_t sm_cmac_k; static uint16_t sm_cmac_message_len; static uint8_t * sm_cmac_message; static sm_key_t sm_cmac_m_last; static sm_key_t sm_cmac_x; static uint8_t sm_cmac_block_current; static uint8_t sm_cmac_block_count; static void (*sm_cmac_done_handler)(uint8_t hash[8]); // @returns 1 if oob data is available // stores oob data in provided 16 byte buffer if not null static int (*sm_get_oob_data)(uint8_t addres_type, bd_addr_t * addr, uint8_t * oob_data) = NULL; // used to notify applicationss that user interaction is neccessary, see sm_notify_t below static btstack_packet_handler_t sm_client_packet_handler = NULL; // horizontal: initiator capabilities // vertial: responder capabilities static const stk_generation_method_t stk_generation_method[5][5] = { { JUST_WORKS, JUST_WORKS, PK_INIT_INPUT, JUST_WORKS, PK_INIT_INPUT }, { JUST_WORKS, JUST_WORKS, PK_INIT_INPUT, JUST_WORKS, PK_INIT_INPUT }, { PK_RESP_INPUT, PK_RESP_INPUT, OK_BOTH_INPUT, JUST_WORKS, PK_RESP_INPUT }, { JUST_WORKS, JUST_WORKS, JUST_WORKS, JUST_WORKS, JUST_WORKS }, { PK_RESP_INPUT, PK_RESP_INPUT, PK_INIT_INPUT, JUST_WORKS, PK_RESP_INPUT }, }; static void sm_run(); // Utils static inline void swapX(uint8_t *src, uint8_t *dst, int len){ int i; for (i = 0; i < len; i++) dst[len - 1 - i] = src[i]; } static inline void swap24(uint8_t src[3], uint8_t dst[3]){ swapX(src, dst, 3); } static inline void swap56(uint8_t src[7], uint8_t dst[7]){ swapX(src, dst, 7); } static inline void swap64(uint8_t src[8], uint8_t dst[8]){ swapX(src, dst, 8); } static inline void swap128(uint8_t src[16], uint8_t dst[16]){ swapX(src, dst, 16); } static void print_hex16(const char * name, uint16_t value){ printf("%-6s 0x%04x\n", name, value); } // @returns 1 if all bytes are 0 static int sm_is_null_random(uint8_t random[8]){ int i; for (i=0; i < 8 ; i++){ if (random[i]) return 0; } return 1; } // Key utils static void sm_reset_tk(){ int i; for (i=0;i<16;i++){ sm_tk[i] = 0; } } // "For example, if a 128-bit encryption key is 0x123456789ABCDEF0123456789ABCDEF0 // and it is reduced to 7 octets (56 bits), then the resulting key is 0x0000000000000000003456789ABCDEF0."" static void sm_truncate_key(sm_key_t key, int max_encryption_size){ int i; for (i = max_encryption_size ; i < 16 ; i++){ key[15-i] = 0; } } // SMP Timeout implementation // Upon transmission of the Pairing Request command or reception of the Pairing Request command, // the Security Manager Timer shall be reset and started. // // The Security Manager Timer shall be reset when an L2CAP SMP command is queued for transmission. // // If the Security Manager Timer reaches 30 seconds, the procedure shall be considered to have failed, // and the local higher layer shall be notified. No further SMP commands shall be sent over the L2CAP // Security Manager Channel. A new SM procedure shall only be performed when a new physical link has been // established. static void sm_timeout_handler(timer_source_t * timer){ printf("SM timeout\n"); sm_state_responding = SM_STATE_TIMEOUT; } static void sm_timeout_start(){ run_loop_remove_timer(&sm_timeout); run_loop_set_timer_handler(&sm_timeout, sm_timeout_handler); run_loop_set_timer(&sm_timeout, 30000); // 30 seconds sm timeout run_loop_add_timer(&sm_timeout); } static void sm_timeout_stop(){ run_loop_remove_timer(&sm_timeout); } static void sm_timeout_reset(){ sm_timeout_stop(); sm_timeout_start(); } // end of sm timeout // GAP Random Address updates static gap_random_address_type_t gap_random_adress_type; static timer_source_t gap_random_address_update_timer; static uint32_t gap_random_adress_update_period; static void gap_random_address_update_handler(timer_source_t * timer){ printf("GAP Random Address Update due\n"); run_loop_set_timer(&gap_random_address_update_timer, gap_random_adress_update_period); run_loop_add_timer(&gap_random_address_update_timer); if (rau_state != RAU_IDLE) return; rau_state = RAU_GET_RANDOM; sm_run(); } static void gap_random_address_update_start(){ run_loop_set_timer_handler(&gap_random_address_update_timer, gap_random_address_update_handler); run_loop_set_timer(&gap_random_address_update_timer, gap_random_adress_update_period); run_loop_add_timer(&gap_random_address_update_timer); } static void gap_random_address_update_stop(){ run_loop_remove_timer(&gap_random_address_update_timer); } static inline void sm_aes128_set_key(sm_key_t key){ memcpy(sm_aes128_key, key, 16); } static inline void sm_aes128_set_plaintext(sm_key_t plaintext){ memcpy(sm_aes128_plaintext, plaintext, 16); } // asserts: sm_aes128_active == 0, hci_can_send_command == 1 static void sm_aes128_start(sm_key_t key, sm_key_t plaintext){ sm_aes128_active = 1; sm_key_t key_flipped, plaintext_flipped; swap128(key, key_flipped); swap128(plaintext, plaintext_flipped); hci_send_cmd(&hci_le_encrypt, key_flipped, plaintext_flipped); } static void sm_ah_r_prime(uint8_t r[3], sm_key_t d1_prime){ // r'= padding || r memset(d1_prime, 0, 16); memcpy(&d1_prime[13], r, 3); } static void sm_d1_d_prime(uint16_t d, uint16_t r, sm_key_t d1_prime){ // d'= padding || r || d memset(d1_prime, 0, 16); net_store_16(d1_prime, 12, r); net_store_16(d1_prime, 14, d); } static void sm_dm_r_prime(uint8_t r[8], sm_key_t r_prime){ // r’ = padding || r memset(r_prime, 0, 16); memcpy(&r_prime[8], r, 8); } // calculate arguments for first AES128 operation in C1 function static void sm_c1_t1(sm_key_t r, uint8_t preq[7], uint8_t pres[7], uint8_t iat, uint8_t rat, sm_key_t t1){ // p1 = pres || preq || rat’ || iat’ // "The octet of iat’ becomes the least significant octet of p1 and the most signifi- // cant octet of pres becomes the most significant octet of p1. // For example, if the 8-bit iat’ is 0x01, the 8-bit rat’ is 0x00, the 56-bit preq // is 0x07071000000101 and the 56 bit pres is 0x05000800000302 then // p1 is 0x05000800000302070710000001010001." sm_key_t p1; swap56(pres, &p1[0]); swap56(preq, &p1[7]); p1[14] = rat; p1[15] = iat; print_key("p1", p1); print_key("r", r); // t1 = r xor p1 int i; for (i=0;i<16;i++){ t1[i] = r[i] ^ p1[i]; } print_key("t1", t1); } // calculate arguments for second AES128 operation in C1 function static void sm_c1_t3(sm_key_t t2, bd_addr_t ia, bd_addr_t ra, sm_key_t t3){ // p2 = padding || ia || ra // "The least significant octet of ra becomes the least significant octet of p2 and // the most significant octet of padding becomes the most significant octet of p2. // For example, if 48-bit ia is 0xA1A2A3A4A5A6 and the 48-bit ra is // 0xB1B2B3B4B5B6 then p2 is 0x00000000A1A2A3A4A5A6B1B2B3B4B5B6. sm_key_t p2; memset(p2, 0, 16); memcpy(&p2[4], ia, 6); memcpy(&p2[10], ra, 6); print_key("p2", p2); // c1 = e(k, t2_xor_p2) int i; for (i=0;i<16;i++){ t3[i] = t2[i] ^ p2[i]; } print_key("t3", t3); } static void sm_s1_r_prime(sm_key_t r1, sm_key_t r2, sm_key_t r_prime){ print_key("r1", r1); print_key("r2", r2); memcpy(&r_prime[8], &r2[8], 8); memcpy(&r_prime[0], &r1[8], 8); } static void sm_notify_client(uint8_t type, uint8_t addr_type, bd_addr_t address, uint32_t passkey, uint16_t index){ sm_event_t event; event.type = type; event.addr_type = addr_type; BD_ADDR_COPY(event.address, address); event.passkey = passkey; event.central_device_db_index = index; log_info("sm_notify_client %02x, addres_type %u, address %s, num '%06u', index %u", event.type, event.addr_type, bd_addr_to_str(event.address), event.passkey, event.central_device_db_index); if (!sm_client_packet_handler) return; sm_client_packet_handler(HCI_EVENT_PACKET, 0, (uint8_t*) &event, sizeof(event)); } static void sm_notify_client_authorization(uint8_t type, uint8_t addr_type, bd_addr_t address, uint8_t result){ sm_event_t event; event.type = type; event.addr_type = addr_type; BD_ADDR_COPY(event.address, address); event.authorization_result = result; log_info("sm_notify_client_authorization %02x, address_type %u, address %s, result %u", event.type, event.addr_type, bd_addr_to_str(event.address), event.authorization_result); if (!sm_client_packet_handler) return; sm_client_packet_handler(HCI_EVENT_PACKET, 0, (uint8_t*) &event, sizeof(event)); } // decide on stk generation based on // - pairing request // - io capabilities // - OOB data availability static void sm_tk_setup(){ // default: just works sm_stk_generation_method = JUST_WORKS; sm_reset_tk(); // query client for OOB data sm_s_have_oob_data = (*sm_get_oob_data)(sm_m_addr_type, &sm_m_address, sm_tk); // If both devices have out of band authentication data, then the Authentication // Requirements Flags shall be ignored when selecting the pairing method and the // Out of Band pairing method shall be used. if (sm_m_have_oob_data && sm_s_have_oob_data){ printf("SM: have OOB data"); print_key("OOB", sm_tk); sm_stk_generation_method = OOB; return; } // If both devices have not set the MITM option in the Authentication Requirements // Flags, then the IO capabilities shall be ignored and the Just Works association // model shall be used. if ( ((sm_m_auth_req & SM_AUTHREQ_MITM_PROTECTION) == 0x00) && ((sm_s_auth_req & SM_AUTHREQ_MITM_PROTECTION) == 0)){ return; } // Also use just works if unknown io capabilites if ((sm_m_io_capabilities > IO_CAPABILITY_KEYBOARD_DISPLAY) || (sm_m_io_capabilities > IO_CAPABILITY_KEYBOARD_DISPLAY)){ return; } // Otherwise the IO capabilities of the devices shall be used to determine the // pairing method as defined in Table 2.4. sm_stk_generation_method = stk_generation_method[sm_s_io_capabilities][sm_m_io_capabilities]; printf("sm_tk_setup: master io cap: %u, slave io cap: %u -> method %u\n", sm_m_io_capabilities, sm_s_io_capabilities, sm_stk_generation_method); } static int sm_key_distribution_flags_for_set(uint8_t key_set){ int flags = 0; if (key_set & SM_KEYDIST_ENC_KEY){ flags |= SM_KEYDIST_FLAG_ENCRYPTION_INFORMATION; flags |= SM_KEYDIST_FLAG_MASTER_IDENTIFICATION; } if (key_set & SM_KEYDIST_ID_KEY){ flags |= SM_KEYDIST_FLAG_IDENTITY_INFORMATION; flags |= SM_KEYDIST_FLAG_IDENTITY_ADDRESS_INFORMATION; } if (key_set & SM_KEYDIST_SIGN){ flags |= SM_KEYDIST_FLAG_SIGNING_IDENTIFICATION; } return flags; } static void sm_setup_key_distribution(uint8_t key_set){ // TODO: handle initiator case here // distribute keys as requested by initiator sm_key_distribution_received_set = 0; sm_key_distribution_send_set = sm_key_distribution_flags_for_set(key_set); } // CMAC Implementation using AES128 engine static void sm_shift_left_by_one_bit_inplace(int len, uint8_t * data){ int i; int carry = 0; for (i=len-1; i >= 0 ; i--){ int new_carry = data[i] >> 7; data[i] = data[i] << 1 | carry; carry = new_carry; } } static int sm_cmac_last_block_complete(){ if (sm_cmac_message_len == 0) return 0; return (sm_cmac_message_len & 0x0f) == 0; } void sm_cmac_start(sm_key_t k, uint16_t message_len, uint8_t * message, void (*done_handler)(uint8_t hash[8])){ memcpy(sm_cmac_k, k, 16); sm_cmac_message_len = message_len; sm_cmac_message = message; sm_cmac_done_handler = done_handler; sm_cmac_block_current = 0; memset(sm_cmac_x, 0, 16); // step 2: n := ceil(len/const_Bsize); sm_cmac_block_count = (message_len + 15) / 16; // step 3: .. if (sm_cmac_block_count==0){ sm_cmac_block_count = 1; } // first, we need to compute l for k1, k2, and m_last sm_cmac_state = CMAC_CALC_SUBKEYS; // let's go sm_run(); } int sm_cmac_ready(){ return sm_cmac_state == CMAC_IDLE; } static void sm_cmac_handle_aes_engine_ready(){ switch (sm_cmac_state){ case CMAC_CALC_SUBKEYS: { sm_key_t const_zero; memset(const_zero, 0, 16); sm_aes128_start(sm_cmac_k, const_zero); sm_cmac_state++; break; } case CMAC_CALC_MI: { int j; sm_key_t y; for (j=0;j<16;j++){ y[j] = sm_cmac_x[j] ^ sm_cmac_message[sm_cmac_block_current*16 + j]; } sm_cmac_block_current++; sm_aes128_start(sm_cmac_k, y); sm_cmac_state++; break; } case CMAC_CALC_MLAST: { int i; sm_key_t y; for (i=0;i<16;i++){ y[i] = sm_cmac_x[i] ^ sm_cmac_m_last[i]; } print_key("Y", y); sm_cmac_block_current++; sm_aes128_start(sm_cmac_k, y); sm_cmac_state++; break; } default: printf("sm_cmac_handle_aes_engine_ready called in state %u\n", sm_cmac_state); break; } } static void sm_cmac_handle_encryption_result(sm_key_t data){ switch (sm_cmac_state){ case CMAC_W4_SUBKEYS: { sm_key_t k1; memcpy(k1, data, 16); sm_shift_left_by_one_bit_inplace(16, k1); if (data[0] & 0x80){ k1[15] ^= 0x87; } sm_key_t k2; memcpy(k2, k1, 16); sm_shift_left_by_one_bit_inplace(16, k2); if (k1[0] & 0x80){ k2[15] ^= 0x87; } print_key("k", sm_cmac_k); print_key("k1", k1); print_key("k2", k2); // step 4: set m_last int i; if (sm_cmac_last_block_complete()){ for (i=0;i<16;i++){ sm_cmac_m_last[i] = sm_cmac_message[sm_cmac_message_len - 16 + i] ^ k1[i]; } } else { int valid_octets_in_last_block = sm_cmac_message_len & 0x0f; for (i=0;i<16;i++){ if (i < valid_octets_in_last_block){ sm_cmac_m_last[i] = sm_cmac_message[(sm_cmac_message_len & 0xfff0) + i] ^ k2[i]; continue; } if (i == valid_octets_in_last_block){ sm_cmac_m_last[i] = 0x80 ^ k2[i]; continue; } sm_cmac_m_last[i] = k2[i]; } } // next sm_cmac_state = sm_cmac_block_current < sm_cmac_block_count - 1 ? CMAC_CALC_MI : CMAC_CALC_MLAST; break; } case CMAC_W4_MI: memcpy(sm_cmac_x, data, 16); sm_cmac_state = sm_cmac_block_current < sm_cmac_block_count - 1 ? CMAC_CALC_MI : CMAC_CALC_MLAST; break; case CMAC_W4_MLAST: // done print_key("CMAC", data); sm_cmac_done_handler(data); break; default: printf("sm_cmac_handle_encryption_result called in state %u\n", sm_cmac_state); break; } } static int sm_key_distribution_done(){ if (sm_key_distribution_send_set) return 0; int recv_flags = sm_key_distribution_flags_for_set(sm_m_key_distribution); return recv_flags == sm_key_distribution_received_set; } static void sm_pdu_received_in_wrong_state(){ sm_pairing_failed_reason = SM_REASON_UNSPECIFIED_REASON; sm_state_responding = SM_STATE_SEND_PAIRING_FAILED; } static void sm_run(void){ // assert that we can send either one if (!hci_can_send_packet_now(HCI_COMMAND_DATA_PACKET)) return; if (!hci_can_send_packet_now(HCI_ACL_DATA_PACKET)) return; // distributed key generation switch (dkg_state){ case DKG_CALC_IRK: // already busy? if (sm_aes128_active) break; { // IRK = d1(IR, 1, 0) sm_key_t d1_prime; sm_d1_d_prime(1, 0, d1_prime); // plaintext sm_aes128_start(sm_persistent_ir, d1_prime); dkg_state++; } case DKG_CALC_DHK: // already busy? if (sm_aes128_active) break; { // DHK = d1(IR, 3, 0) sm_key_t d1_prime; sm_d1_d_prime(3, 0, d1_prime); // plaintext sm_aes128_start(sm_persistent_ir, d1_prime); dkg_state++; } return; default: break; } // random address updates switch (rau_state){ case RAU_GET_RANDOM: hci_send_cmd(&hci_le_rand); rau_state++; return; case RAU_GET_ENC: // already busy? if (sm_aes128_active) break; { sm_key_t r_prime; sm_ah_r_prime(sm_random_address, r_prime); sm_aes128_start(sm_persistent_irk, r_prime); rau_state++; return; } case RAU_SET_ADDRESS: printf("New random address: %s\n", bd_addr_to_str(sm_random_address)); hci_send_cmd(&hci_le_set_random_address, sm_random_address); rau_state = RAU_IDLE; return; default: break; } // CSRK device lookup by public or resolvable private address if (sm_central_device_test >= 0){ printf("Central Device Lookup: device %u/%u\n", sm_central_device_test, central_device_db_count()); while (sm_central_device_test < central_device_db_count()){ int addr_type; bd_addr_t addr; sm_key_t irk; central_device_db_info(sm_central_device_test, &addr_type, addr, irk); printf("device type %u, addr: %s\n", addr_type, bd_addr_to_str(addr)); if (sm_m_addr_type == addr_type && memcmp(addr, sm_m_address, 6) == 0){ printf("Central Device Lookup: found CSRK by { addr_type, address} \n"); sm_central_device_matched = sm_central_device_test; sm_central_device_test = -1; central_device_db_csrk(sm_central_device_matched, sm_m_csrk); sm_notify_client(SM_IDENTITY_RESOLVING_SUCCEEDED, sm_m_addr_type, sm_m_address, 0, sm_central_device_matched); break; } if (sm_m_addr_type == 0){ sm_central_device_test++; continue; } if (sm_aes128_active) break; printf("Central Device Lookup: calculate AH\n"); print_key("IRK", irk); sm_key_t r_prime; sm_ah_r_prime(sm_m_address, r_prime); sm_aes128_start(irk, r_prime); sm_central_ah_calculation_active = 1; return; } if (sm_central_device_test >= central_device_db_count()){ printf("Central Device Lookup: not found\n"); sm_central_device_test = -1; sm_notify_client(SM_IDENTITY_RESOLVING_FAILED, sm_m_addr_type, sm_m_address, 0, 0); } } // cmac switch (sm_cmac_state){ case CMAC_CALC_SUBKEYS: case CMAC_CALC_MI: case CMAC_CALC_MLAST: // already busy? if (sm_aes128_active) break; sm_cmac_handle_aes_engine_ready(); return; default: break; } // responding state switch (sm_state_responding){ case SM_STATE_SEND_SECURITY_REQUEST: { uint8_t buffer[2]; buffer[0] = SM_CODE_SECURITY_REQUEST; buffer[1] = SM_AUTHREQ_BONDING; l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_state_responding = SM_STATE_IDLE; return; } case SM_STATE_PH1_SEND_PAIRING_RESPONSE: { uint8_t buffer[7]; memcpy(buffer, sm_m_preq, 7); buffer[0] = SM_CODE_PAIRING_RESPONSE; buffer[1] = sm_s_io_capabilities; buffer[2] = sm_s_have_oob_data; buffer[3] = sm_s_auth_req; buffer[4] = sm_max_encryption_key_size; memcpy(sm_s_pres, buffer, 7); // for validate l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); // notify client for: JUST WORKS confirm, PASSKEY display or input sm_user_response = SM_USER_RESPONSE_IDLE; switch (sm_stk_generation_method){ case PK_RESP_INPUT: sm_user_response = SM_USER_RESPONSE_PENDING; sm_notify_client(SM_PASSKEY_INPUT_NUMBER, sm_m_addr_type, sm_m_address, 0, 0); break; case PK_INIT_INPUT: sm_notify_client(SM_PASSKEY_DISPLAY_NUMBER, sm_m_addr_type, sm_m_address, READ_NET_32(sm_tk, 12), 0); break; case JUST_WORKS: switch (sm_s_io_capabilities){ case IO_CAPABILITY_KEYBOARD_DISPLAY: case IO_CAPABILITY_DISPLAY_YES_NO: sm_user_response = SM_USER_RESPONSE_PENDING; sm_notify_client(SM_JUST_WORKS_REQUEST, sm_m_addr_type, sm_m_address, READ_NET_32(sm_tk, 12), 0); break; default: // cannot ask user break; } break; default: break; } sm_state_responding = SM_STATE_PH1_W4_PAIRING_CONFIRM; return; } case SM_STATE_SEND_LTK_REQUESTED_NEGATIVE_REPLY: hci_send_cmd(&hci_le_long_term_key_negative_reply, sm_response_handle); sm_state_responding = SM_STATE_IDLE; return; case SM_STATE_SEND_PAIRING_FAILED: { uint8_t buffer[2]; buffer[0] = SM_CODE_PAIRING_FAILED; buffer[1] = sm_pairing_failed_reason; l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_stop(); sm_state_responding = SM_STATE_IDLE; break; } case SM_STATE_SEND_PAIRING_RANDOM: { uint8_t buffer[17]; buffer[0] = SM_CODE_PAIRING_RANDOM; swap128(sm_s_random, &buffer[1]); l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); sm_state_responding = SM_STATE_PH2_W4_LTK_REQUEST; break; } case SM_STATE_PH2_GET_RANDOM_TK: case SM_STATE_PH2_C1_GET_RANDOM_A: case SM_STATE_PH2_C1_GET_RANDOM_B: case SM_STATE_PH3_GET_RANDOM: case SM_STATE_PH3_GET_DIV: hci_send_cmd(&hci_le_rand); sm_state_responding++; return; case SM_STATE_PH2_C1_GET_ENC_A: case SM_STATE_PH2_C1_GET_ENC_B: case SM_STATE_PH2_C1_GET_ENC_C: case SM_STATE_PH2_C1_GET_ENC_D: case SM_STATE_PH2_CALC_STK: case SM_STATE_PH3_Y_GET_ENC: case SM_STATE_PH3_LTK_GET_ENC: case SM_STATE_PH4_Y_GET_ENC: case SM_STATE_PH4_LTK_GET_ENC: // already busy? if (sm_aes128_active) break; sm_aes128_start(sm_aes128_key, sm_aes128_plaintext); sm_state_responding++; return; case SM_STATE_PH2_C1_SEND_PAIRING_CONFIRM: { uint8_t buffer[17]; buffer[0] = SM_CODE_PAIRING_CONFIRM; swap128(sm_s_confirm, &buffer[1]); l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); sm_state_responding = SM_STATE_PH2_W4_PAIRING_RANDOM; return; } case SM_STATE_PH2_SEND_STK: { sm_key_t stk_flipped; swap128(sm_s_ltk, stk_flipped); hci_send_cmd(&hci_le_long_term_key_request_reply, sm_response_handle, stk_flipped); sm_state_responding = SM_STATE_PH2_W4_CONNECTION_ENCRYPTED; return; } case SM_STATE_PH4_SEND_LTK: { sm_key_t ltk_flipped; swap128(sm_s_ltk, ltk_flipped); hci_send_cmd(&hci_le_long_term_key_request_reply, sm_response_handle, ltk_flipped); sm_state_responding = SM_STATE_IDLE; return; } case SM_STATE_DISTRIBUTE_KEYS: if (sm_key_distribution_send_set & SM_KEYDIST_FLAG_ENCRYPTION_INFORMATION){ sm_key_distribution_send_set &= ~SM_KEYDIST_FLAG_ENCRYPTION_INFORMATION; uint8_t buffer[17]; buffer[0] = SM_CODE_ENCRYPTION_INFORMATION; swap128(sm_s_ltk, &buffer[1]); l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); return; } if (sm_key_distribution_send_set & SM_KEYDIST_FLAG_MASTER_IDENTIFICATION){ sm_key_distribution_send_set &= ~SM_KEYDIST_FLAG_MASTER_IDENTIFICATION; uint8_t buffer[11]; buffer[0] = SM_CODE_MASTER_IDENTIFICATION; bt_store_16(buffer, 1, sm_s_ediv); swap64(sm_s_rand, &buffer[3]); l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); return; } if (sm_key_distribution_send_set & SM_KEYDIST_FLAG_IDENTITY_INFORMATION){ sm_key_distribution_send_set &= ~SM_KEYDIST_FLAG_IDENTITY_INFORMATION; uint8_t buffer[17]; buffer[0] = SM_CODE_IDENTITY_INFORMATION; swap128(sm_persistent_irk, &buffer[1]); l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); return; } if (sm_key_distribution_send_set & SM_KEYDIST_FLAG_IDENTITY_ADDRESS_INFORMATION){ sm_key_distribution_send_set &= ~SM_KEYDIST_FLAG_IDENTITY_ADDRESS_INFORMATION; uint8_t buffer[8]; buffer[0] = SM_CODE_IDENTITY_ADDRESS_INFORMATION; buffer[1] = sm_s_addr_type; bt_flip_addr(&buffer[2], sm_s_address); l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); return; } if (sm_key_distribution_send_set & SM_KEYDIST_FLAG_SIGNING_IDENTIFICATION){ sm_key_distribution_send_set &= ~SM_KEYDIST_FLAG_SIGNING_IDENTIFICATION; uint8_t buffer[17]; buffer[0] = SM_CODE_SIGNING_INFORMATION; // swap128(sm_s_csrk, &buffer[1]); memset(&buffer[1], 0, 16); // csrk not calculated l2cap_send_connectionless(sm_response_handle, L2CAP_CID_SECURITY_MANAGER_PROTOCOL, (uint8_t*) buffer, sizeof(buffer)); sm_timeout_reset(); return; } if (sm_key_distribution_done()){ sm_timeout_stop(); sm_state_responding = SM_STATE_IDLE; } break; default: break; } } static void sm_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ if (packet_type != SM_DATA_PACKET) return; if (handle != sm_response_handle){ printf("sm_packet_handler: packet from handle %u, but expecting from %u\n", handle, sm_response_handle); return; } if (packet[0] == SM_CODE_PAIRING_FAILED){ sm_state_responding = SM_STATE_IDLE; return; } switch (sm_state_responding){ // a sm timeout requries a new physical connection case SM_STATE_TIMEOUT: return; case SM_STATE_IDLE: { if (packet[0] != SM_CODE_PAIRING_REQUEST){ sm_pdu_received_in_wrong_state(); break;; } // store key distribtion request sm_m_io_capabilities = packet[1]; sm_m_have_oob_data = packet[2]; sm_m_auth_req = packet[3]; sm_m_max_encryption_key_size = packet[4]; // assert max encryption size above our minimum if (sm_m_max_encryption_key_size < sm_min_encryption_key_size){ sm_pairing_failed_reason = SM_REASON_ENCRYPTION_KEY_SIZE; sm_state_responding = SM_STATE_SEND_PAIRING_FAILED; break; } // min{} sm_actual_encryption_key_size = sm_max_encryption_key_size; if (sm_m_max_encryption_key_size < sm_max_encryption_key_size){ sm_actual_encryption_key_size = sm_m_max_encryption_key_size; } // setup key distribution sm_m_key_distribution = packet[5]; sm_setup_key_distribution(packet[6]); // for validate memcpy(sm_m_preq, packet, 7); // start SM timeout sm_timeout_start(); // decide on STK generation method sm_tk_setup(); printf("SMP: generation method %u\n", sm_stk_generation_method); // check if STK generation method is acceptable by client int ok = 0; switch (sm_stk_generation_method){ case JUST_WORKS: ok = (sm_accepted_stk_generation_methods & SM_STK_GENERATION_METHOD_JUST_WORKS) != 0; break; case PK_RESP_INPUT: case PK_INIT_INPUT: case OK_BOTH_INPUT: ok = (sm_accepted_stk_generation_methods & SM_STK_GENERATION_METHOD_PASSKEY) != 0; break; case OOB: ok = (sm_accepted_stk_generation_methods & SM_STK_GENERATION_METHOD_OOB) != 0; break; } if (!ok){ sm_pairing_failed_reason = SM_REASON_AUTHENTHICATION_REQUIREMENTS; sm_state_responding = SM_STATE_SEND_PAIRING_FAILED; break; } // JUST WORKS doens't provide authentication sm_connection_authenticated = sm_stk_generation_method == JUST_WORKS ? 0 : 1; // generate random number first, if we need to show passkey if (sm_stk_generation_method == PK_INIT_INPUT){ sm_state_responding = SM_STATE_PH2_GET_RANDOM_TK; break; } sm_state_responding = SM_STATE_PH1_SEND_PAIRING_RESPONSE; break; } case SM_STATE_PH1_W4_PAIRING_CONFIRM: if (packet[0] != SM_CODE_PAIRING_CONFIRM){ sm_pdu_received_in_wrong_state(); break;; } // received confirm value swap128(&packet[1], sm_m_confirm); // notify client to hide shown passkey if (sm_stk_generation_method == PK_INIT_INPUT){ sm_notify_client(SM_PASSKEY_DISPLAY_CANCEL, sm_m_addr_type, sm_m_address, 0, 0); } // handle user cancel pairing? if (sm_user_response == SM_USER_RESPONSE_DECLINE){ sm_pairing_failed_reason = SM_REASON_PASSKEYT_ENTRY_FAILED; sm_state_responding = SM_STATE_SEND_PAIRING_FAILED; break; } // wait for user action? if (sm_user_response == SM_USER_RESPONSE_PENDING){ sm_state_responding = SM_STATE_PH1_W4_USER_RESPONSE; break; } // calculate and send s_confirm sm_state_responding = SM_STATE_PH2_C1_GET_RANDOM_A; break; case SM_STATE_PH2_W4_PAIRING_RANDOM: if (packet[0] != SM_CODE_PAIRING_RANDOM){ sm_pdu_received_in_wrong_state(); break;; } // received random value swap128(&packet[1], sm_m_random); // use aes128 engine // calculate m_confirm using aes128 engine - step 1 sm_aes128_set_key(sm_tk); sm_c1_t1(sm_m_random, sm_m_preq, sm_s_pres, sm_m_addr_type, sm_s_addr_type, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH2_C1_GET_ENC_C; break; case SM_STATE_DISTRIBUTE_KEYS: switch(packet[0]){ case SM_CODE_ENCRYPTION_INFORMATION: sm_key_distribution_received_set |= SM_KEYDIST_FLAG_ENCRYPTION_INFORMATION; // swap128(&packet[1], sm_m_ltk); break; case SM_CODE_MASTER_IDENTIFICATION: sm_key_distribution_received_set |= SM_KEYDIST_FLAG_MASTER_IDENTIFICATION; // sm_m_ediv = READ_BT_16(packet, 1); // swap64(&packet[3], sm_m_rand); break; case SM_CODE_IDENTITY_INFORMATION: sm_key_distribution_received_set |= SM_KEYDIST_FLAG_IDENTITY_INFORMATION; swap128(&packet[1], sm_m_irk); break; case SM_CODE_IDENTITY_ADDRESS_INFORMATION: sm_key_distribution_received_set |= SM_KEYDIST_FLAG_IDENTITY_ADDRESS_INFORMATION; // note: we don't update addr_type and address as higher layer would get confused // note: if needed, we could use a different variable pair // sm_m_addr_type = packet[1]; // BD_ADDR_COPY(sm_m_address, &packet[2]); break; case SM_CODE_SIGNING_INFORMATION: sm_key_distribution_received_set |= SM_KEYDIST_FLAG_SIGNING_IDENTIFICATION; swap128(&packet[1], sm_m_csrk); // store, if: it's a public address, or, we got an IRK if (sm_m_addr_type == 0 || (sm_key_distribution_received_set & SM_KEYDIST_FLAG_IDENTITY_INFORMATION)) { sm_central_device_matched = central_device_db_add(sm_m_addr_type, sm_m_address, sm_m_irk, sm_m_csrk); // also tell client about it if (sm_central_device_matched >= 0){ sm_notify_client(SM_IDENTITY_RESOLVING_SUCCEEDED, sm_m_addr_type, sm_m_address, 0, sm_central_device_matched); } break; } break; default: // Unexpected PDU printf("Unexpected PDU %u in SM_STATE_DISTRIBUTE_KEYS\n", packet[0]); break; } // done with key distribution? if (sm_key_distribution_done()){ sm_timeout_stop(); sm_state_responding = SM_STATE_IDLE; } break; default: // Unexpected PDU printf("Unexpected PDU %u in state %u\n", packet[0], sm_state_responding); break; } // try to send preparared packet sm_run(); } static void sm_event_packet_handler (void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ sm_run(); switch (packet_type) { case HCI_EVENT_PACKET: switch (packet[0]) { case BTSTACK_EVENT_STATE: // bt stack activated, get started if (packet[2] == HCI_STATE_WORKING) { printf("HCI Working!\n"); dkg_state = DKG_CALC_IRK; sm_run(); return; // don't notify app packet handler just yet } break; case HCI_EVENT_LE_META: switch (packet[2]) { case HCI_SUBEVENT_LE_CONNECTION_COMPLETE: // only single connection for peripheral if (sm_response_handle){ printf("Already connected, ignoring incoming connection\n"); return; } sm_response_handle = READ_BT_16(packet, 4); sm_m_addr_type = packet[7]; bt_flip_addr(sm_m_address, &packet[8]); sm_reset_tk(); hci_le_advertisement_address(&sm_s_addr_type, &sm_s_address); printf("Incoming connection, own address %s\n", bd_addr_to_str(sm_s_address)); // reset security properties sm_connection_encrypted = 0; sm_connection_authenticated = 0; sm_connection_authorization_state = AUTHORIZATION_UNKNOWN; // request security if (sm_s_request_security){ sm_state_responding = SM_STATE_SEND_SECURITY_REQUEST; } // try to lookup device sm_central_device_test = 0; sm_central_device_matched = -1; sm_notify_client(SM_IDENTITY_RESOLVING_STARTED, sm_m_addr_type, sm_m_address, 0, 0); break; case HCI_SUBEVENT_LE_LONG_TERM_KEY_REQUEST: log_info("LTK Request: state %u", sm_state_responding); if (sm_state_responding == SM_STATE_PH2_W4_LTK_REQUEST){ // calculate STK log_info("LTK Request: calculating STK"); sm_aes128_set_key(sm_tk); sm_s1_r_prime(sm_s_random, sm_m_random, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH2_CALC_STK; break; } // re-establish previously used LTK using Rand and EDIV swap64(&packet[5], sm_s_rand); sm_s_ediv = READ_BT_16(packet, 13); // assume that we don't have a LTK for ediv == 0 and random == null if (sm_s_ediv == 0 && sm_is_null_random(sm_s_rand)){ printf("LTK Request: ediv & random are empty\n"); sm_state_responding = SM_STATE_SEND_LTK_REQUESTED_NEGATIVE_REPLY; break; } // re-establish used key encryption size // no db for encryption size hack: encryption size is stored in lowest nibble of sm_s_rand sm_actual_encryption_key_size = (sm_s_rand[7] & 0x0f) + 1; // no db for authenticated flag hack: flag is stored in bit 4 of LSB sm_connection_authenticated = (sm_s_rand[7] & 0x10) >> 4; log_info("LTK Request: recalculating with ediv 0x%04x", sm_s_ediv); // dhk = d1(IR, 3, 0) - enc // y = dm(dhk, rand) - enc // div = y xor ediv // ltk = d1(ER, div, 0) - enc // Y = dm(DHK, Rand) sm_aes128_set_key(sm_persistent_dhk); sm_dm_r_prime(sm_s_rand, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH4_Y_GET_ENC; // sm_s_div = sm_div(sm_persistent_dhk, sm_s_rand, sm_s_ediv); // sm_s_ltk(sm_persistent_er, sm_s_div, sm_s_ltk); break; default: break; } break; case HCI_EVENT_ENCRYPTION_CHANGE: if (sm_response_handle != READ_BT_16(packet, 3)) break; sm_connection_encrypted = packet[5]; log_info("Eencryption state change: %u", sm_connection_encrypted); if (!sm_connection_encrypted) break; if (sm_state_responding == SM_STATE_PH2_W4_CONNECTION_ENCRYPTED) { sm_state_responding = SM_STATE_PH3_GET_RANDOM; } break; case HCI_EVENT_DISCONNECTION_COMPLETE: sm_state_responding = SM_STATE_IDLE; sm_response_handle = 0; break; case HCI_EVENT_COMMAND_COMPLETE: if (COMMAND_COMPLETE_EVENT(packet, hci_le_encrypt)){ sm_aes128_active = 0; if (sm_central_ah_calculation_active){ sm_central_ah_calculation_active = 0; // compare calulated address against connecting device uint8_t hash[3]; swap24(&packet[6], hash); if (memcmp(&sm_m_address[3], hash, 3) == 0){ // found sm_central_device_matched = sm_central_device_test; sm_central_device_test = -1; central_device_db_csrk(sm_central_device_matched, sm_m_csrk); sm_notify_client(SM_IDENTITY_RESOLVING_SUCCEEDED, sm_m_addr_type, sm_m_address, 0, sm_central_device_matched); log_info("Central Device Lookup: matched resolvable private address"); break; } // no match sm_central_device_test++; break; } switch (dkg_state){ case DKG_W4_IRK: swap128(&packet[6], sm_persistent_irk); print_key("irk", sm_persistent_irk); dkg_state++; break; case DKG_W4_DHK: swap128(&packet[6], sm_persistent_dhk); print_key("dhk", sm_persistent_dhk); dkg_state ++; // SM INIT FINISHED, start application code - TODO untangle that if (sm_client_packet_handler) { uint8_t event[] = { BTSTACK_EVENT_STATE, 0, HCI_STATE_WORKING }; sm_client_packet_handler(HCI_EVENT_PACKET, 0, (uint8_t*) event, sizeof(event)); } break; default: break; } switch (rau_state){ case RAU_W4_ENC: swap24(&packet[6], &sm_random_address[3]); rau_state++; break; default: break; } switch (sm_cmac_state){ case CMAC_W4_SUBKEYS: case CMAC_W4_MI: case CMAC_W4_MLAST: { sm_key_t t; swap128(&packet[6], t); sm_cmac_handle_encryption_result(t); } break; default: break; } switch (sm_state_responding){ case SM_STATE_PH2_C1_W4_ENC_A: case SM_STATE_PH2_C1_W4_ENC_C: { sm_aes128_set_key(sm_tk); sm_key_t t2; swap128(&packet[6], t2); sm_c1_t3(t2, sm_m_address, sm_s_address, sm_aes128_plaintext); } sm_state_responding++; break; case SM_STATE_PH2_C1_W4_ENC_B: swap128(&packet[6], sm_s_confirm); print_key("c1!", sm_s_confirm); sm_state_responding++; break; case SM_STATE_PH2_C1_W4_ENC_D: { sm_key_t m_confirm_test; swap128(&packet[6], m_confirm_test); print_key("c1!", m_confirm_test); if (memcmp(sm_m_confirm, m_confirm_test, 16) == 0){ // send s_random sm_state_responding = SM_STATE_SEND_PAIRING_RANDOM; break; } sm_pairing_failed_reason = SM_REASON_CONFIRM_VALUE_FAILED; sm_state_responding = SM_STATE_SEND_PAIRING_FAILED; } break; case SM_STATE_PH2_W4_STK: swap128(&packet[6], sm_s_ltk); sm_truncate_key(sm_s_ltk, sm_actual_encryption_key_size); print_key("stk", sm_s_ltk); sm_state_responding = SM_STATE_PH2_SEND_STK; break; case SM_STATE_PH3_Y_W4_ENC:{ sm_key_t y128; swap128(&packet[6], y128); sm_s_y = READ_NET_16(y128, 14); print_hex16("y", sm_s_y); // PH3B3 - calculate EDIV sm_s_ediv = sm_s_y ^ sm_s_div; print_hex16("ediv", sm_s_ediv); // PH3B4 - calculate LTK - enc // LTK = d1(ER, DIV, 0)) sm_aes128_set_key(sm_persistent_er); sm_d1_d_prime(sm_s_div, 0, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH3_LTK_GET_ENC; break; } case SM_STATE_PH4_Y_W4_ENC:{ sm_key_t y128; swap128(&packet[6], y128); sm_s_y = READ_NET_16(y128, 14); print_hex16("y", sm_s_y); // PH3B3 - calculate DIV sm_s_div = sm_s_y ^ sm_s_ediv; print_hex16("ediv", sm_s_ediv); // PH3B4 - calculate LTK - enc // LTK = d1(ER, DIV, 0)) sm_aes128_set_key(sm_persistent_er); sm_d1_d_prime(sm_s_div, 0, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH4_LTK_GET_ENC; break; } case SM_STATE_PH3_LTK_W4_ENC: swap128(&packet[6], sm_s_ltk); print_key("ltk", sm_s_ltk); // distribute keys sm_state_responding = SM_STATE_DISTRIBUTE_KEYS; break; case SM_STATE_PH4_LTK_W4_ENC: swap128(&packet[6], sm_s_ltk); sm_truncate_key(sm_s_ltk, sm_actual_encryption_key_size); print_key("ltk", sm_s_ltk); sm_state_responding = SM_STATE_PH4_SEND_LTK; break; default: break; } } if (COMMAND_COMPLETE_EVENT(packet, hci_le_rand)){ switch (rau_state){ case RAU_W4_RANDOM: // non-resolvable vs. resolvable switch (gap_random_adress_type){ case GAP_RANDOM_ADDRESS_RESOLVABLE: // resolvable: use random as prand and calc address hash // "The two most significant bits of prand shall be equal to ‘0’ and ‘1" memcpy(sm_random_address, &packet[6], 3); sm_random_address[0] &= 0x3f; sm_random_address[0] |= 0x40; rau_state = RAU_GET_ENC; break; case GAP_RANDOM_ADDRESS_NON_RESOLVABLE: default: // "The two most significant bits of the address shall be equal to ‘0’"" memcpy(sm_random_address, &packet[6], 6); sm_random_address[0] &= 0x3f; rau_state = RAU_SET_ADDRESS; break; } break; default: break; } switch (sm_state_responding){ case SM_STATE_PH2_W4_RANDOM_TK: { // map random to 0-999999 without speding much cycles on a modulus operation uint32_t tk = * (uint32_t*) &packet[6]; // random endianess tk = tk & 0xfffff; // 1048575 if (tk >= 999999){ tk = tk - 999999; } sm_reset_tk(); net_store_32(sm_tk, 12, tk); // continue with phase 1 sm_state_responding = SM_STATE_PH1_SEND_PAIRING_RESPONSE; break; } case SM_STATE_PH2_C1_W4_RANDOM_A: memcpy(&sm_s_random[0], &packet[6], 8); // random endinaness sm_state_responding = SM_STATE_PH2_C1_GET_RANDOM_B; break; case SM_STATE_PH2_C1_W4_RANDOM_B: memcpy(&sm_s_random[8], &packet[6], 8); // random endinaness // calculate s_confirm manually // sm_c1(sm_tk, sm_s_random, sm_m_preq, sm_s_pres, sm_m_addr_type, sm_s_addr_type, sm_m_address, sm_s_address, sm_s_confirm); // calculate s_confirm using aes128 engine - step 1 sm_aes128_set_key(sm_tk); sm_c1_t1(sm_s_random, sm_m_preq, sm_s_pres, sm_m_addr_type, sm_s_addr_type, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH2_C1_GET_ENC_A; break; case SM_STATE_PH3_W4_RANDOM: swap64(&packet[6], sm_s_rand); // no db for encryption size hack: encryption size is stored in lowest nibble of sm_s_rand sm_s_rand[7] = (sm_s_rand[7] & 0xf0) + (sm_actual_encryption_key_size - 1); // no db for authenticated flag hack: store flag in bit 4 of LSB sm_s_rand[7] = (sm_s_rand[7] & 0xef) + (sm_connection_authenticated << 4); sm_state_responding = SM_STATE_PH3_GET_DIV; break; case SM_STATE_PH3_W4_DIV: // use 16 bit from random value as div sm_s_div = READ_NET_16(packet, 6); print_hex16("div", sm_s_div); // PH3B2 - calculate Y from - enc // Y = dm(DHK, Rand) sm_aes128_set_key(sm_persistent_dhk); sm_dm_r_prime(sm_s_rand, sm_aes128_plaintext); sm_state_responding = SM_STATE_PH3_Y_GET_ENC; break; default: break; } break; } } // forward packet to higher layer if (sm_client_packet_handler){ sm_client_packet_handler(packet_type, 0, packet, size); } } sm_run(); } // Security Manager Client API void sm_register_oob_data_callback( int (*get_oob_data_callback)(uint8_t addres_type, bd_addr_t * addr, uint8_t * oob_data)){ sm_get_oob_data = get_oob_data_callback; } void sm_register_packet_handler(btstack_packet_handler_t handler){ sm_client_packet_handler = handler; } void sm_set_accepted_stk_generation_methods(uint8_t accepted_stk_generation_methods){ sm_accepted_stk_generation_methods = accepted_stk_generation_methods; } void sm_set_encryption_key_size_range(uint8_t min_size, uint8_t max_size){ sm_min_encryption_key_size = min_size; sm_max_encryption_key_size = max_size; } void sm_set_authentication_requirements(uint8_t auth_req){ sm_s_auth_req = auth_req; } void sm_set_io_capabilities(io_capability_t io_capability){ sm_s_io_capabilities = io_capability; } void sm_set_request_security(int enable){ sm_s_request_security = enable; } void sm_set_er(sm_key_t er){ memcpy(sm_persistent_er, er, 16); } void sm_set_ir(sm_key_t ir){ memcpy(sm_persistent_ir, ir, 16); // sm_dhk(sm_persistent_ir, sm_persistent_dhk); // sm_irk(sm_persistent_ir, sm_persistent_irk); } /** * @brief Trigger Security Request * @note Not used normally. Bonding is triggered by access to protected attributes in ATT Server */ void sm_send_security_request(){ sm_state_responding = SM_STATE_SEND_SECURITY_REQUEST; sm_run(); } void sm_init(){ // set some (BTstack default) ER and IR int i; sm_key_t er; sm_key_t ir; for (i=0;i<16;i++){ er[i] = 0x30 + i; ir[i] = 0x90 + i; } sm_set_er(er); sm_set_ir(ir); sm_state_responding = SM_STATE_IDLE; // defaults sm_accepted_stk_generation_methods = SM_STK_GENERATION_METHOD_JUST_WORKS | SM_STK_GENERATION_METHOD_OOB | SM_STK_GENERATION_METHOD_PASSKEY; sm_max_encryption_key_size = 16; sm_min_encryption_key_size = 7; sm_aes128_active = 0; sm_cmac_state = CMAC_IDLE; sm_central_device_test = -1; // no private address to resolve yet sm_central_ah_calculation_active = 0; gap_random_adress_update_period = 15 * 60 * 1000; // attach to lower layers l2cap_register_fixed_channel(sm_packet_handler, L2CAP_CID_SECURITY_MANAGER_PROTOCOL); l2cap_register_packet_handler(sm_event_packet_handler); } static int sm_get_connection(uint8_t addr_type, bd_addr_t address){ // TODO compare to current connection return 1; } // @returns 0 if not encrypted, 7-16 otherwise int sm_encryption_key_size(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return 0; // wrong connection if (!sm_connection_encrypted) return 0; return sm_actual_encryption_key_size; } int sm_authenticated(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return 0; // wrong connection if (!sm_connection_encrypted) return 0; // unencrypted connection cannot be authenticated return sm_connection_authenticated; } authorization_state_t sm_authorization_state(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return 0; // wrong connection if (!sm_connection_encrypted) return 0; // unencrypted connection cannot be authorized if (!sm_connection_authenticated) return 0; // unauthenticatd connection cannot be authorized return sm_connection_authorization_state; } // request authorization void sm_request_authorization(uint8_t addr_type, bd_addr_t address){ sm_connection_authorization_state = AUTHORIZATION_PENDING; sm_notify_client(SM_AUTHORIZATION_REQUEST, sm_m_addr_type, sm_m_address, 0, 0); } // called by client app on authorization request void sm_authorization_decline(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return; // wrong connection sm_connection_authorization_state = AUTHORIZATION_DECLINED; sm_notify_client_authorization(SM_AUTHORIZATION_RESULT, sm_m_addr_type, sm_m_address, 0); } void sm_authorization_grant(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return; // wrong connection sm_connection_authorization_state = AUTHORIZATION_GRANTED; sm_notify_client_authorization(SM_AUTHORIZATION_RESULT, sm_m_addr_type, sm_m_address, 1); } // GAP Bonding API void sm_bonding_decline(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return; // wrong connection sm_user_response = SM_USER_RESPONSE_DECLINE; if (sm_state_responding == SM_STATE_PH1_W4_USER_RESPONSE){ sm_pairing_failed_reason = SM_REASON_PASSKEYT_ENTRY_FAILED; sm_state_responding = SM_STATE_SEND_PAIRING_FAILED; } sm_run(); } void sm_just_works_confirm(uint8_t addr_type, bd_addr_t address){ if (!sm_get_connection(addr_type, address)) return; // wrong connection sm_user_response = SM_USER_RESPONSE_CONFIRM; if (sm_state_responding == SM_STATE_PH1_W4_USER_RESPONSE){ sm_state_responding = SM_STATE_PH2_C1_GET_RANDOM_A; } sm_run(); } void sm_passkey_input(uint8_t addr_type, bd_addr_t address, uint32_t passkey){ if (!sm_get_connection(addr_type, address)) return; // wrong connection sm_reset_tk(); net_store_32(sm_tk, 12, passkey); sm_user_response = SM_USER_RESPONSE_PASSKEY; if (sm_state_responding == SM_STATE_PH1_W4_USER_RESPONSE){ sm_state_responding = SM_STATE_PH2_C1_GET_RANDOM_A; } sm_run(); } // GAP LE API void gap_random_address_set_mode(gap_random_address_type_t random_address_type){ gap_random_address_update_stop(); gap_random_adress_type = random_address_type; if (random_address_type == GAP_RANDOM_ADDRESS_TYPE_OFF) return; gap_random_address_update_start(); } void gap_random_address_set_update_period(int period_ms){ gap_random_adress_update_period = period_ms; if (gap_random_adress_type == GAP_RANDOM_ADDRESS_TYPE_OFF) return; gap_random_address_update_stop(); gap_random_address_update_start(); }