93 lines
3.4 KiB
C
93 lines
3.4 KiB
C
/*
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* This file is part of the Pico FIDO distribution (https://github.com/polhenarejos/pico-fido).
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* Copyright (c) 2022 Pol Henarejos.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, version 3.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include "pico_keys.h"
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#include "fido.h"
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#include "apdu.h"
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#include "ctap.h"
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#include "random.h"
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#include "files.h"
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#include "credential.h"
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int cmd_authenticate() {
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CTAP_AUTHENTICATE_REQ *req = (CTAP_AUTHENTICATE_REQ *) apdu.data;
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CTAP_AUTHENTICATE_RESP *resp = (CTAP_AUTHENTICATE_RESP *) res_APDU;
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//if (scan_files_fido(true) != PICOKEY_OK)
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// return SW_EXEC_ERROR();
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if (apdu.nc < CTAP_CHAL_SIZE + CTAP_APPID_SIZE + 1 + 1) {
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return SW_WRONG_DATA();
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}
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if (req->keyHandleLen < KEY_HANDLE_LEN) {
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return SW_INCORRECT_PARAMS();
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}
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if (P1(apdu) == CTAP_AUTH_ENFORCE && wait_button_pressed() == true) {
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return SW_CONDITIONS_NOT_SATISFIED();
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}
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mbedtls_ecp_keypair key;
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mbedtls_ecp_keypair_init(&key);
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int ret = 0;
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uint8_t *tmp_kh = (uint8_t *) calloc(1, req->keyHandleLen);
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memcpy(tmp_kh, req->keyHandle, req->keyHandleLen);
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if (credential_verify(tmp_kh, req->keyHandleLen, req->appId, false) == 0) {
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ret = fido_load_key(FIDO2_CURVE_P256, req->keyHandle, &key);
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}
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else {
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ret = derive_key(req->appId, false, req->keyHandle, MBEDTLS_ECP_DP_SECP256R1, &key);
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if (verify_key(req->appId, req->keyHandle, &key) != 0) {
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mbedtls_ecp_keypair_free(&key);
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free(tmp_kh);
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return SW_INCORRECT_PARAMS();
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}
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}
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free(tmp_kh);
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if (ret != PICOKEY_OK) {
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mbedtls_ecp_keypair_free(&key);
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return SW_EXEC_ERROR();
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}
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if (P1(apdu) == CTAP_AUTH_CHECK_ONLY) {
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mbedtls_ecp_keypair_free(&key);
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return SW_CONDITIONS_NOT_SATISFIED();
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}
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resp->flags = 0;
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resp->flags |= P1(apdu) == CTAP_AUTH_ENFORCE ? CTAP_AUTH_FLAG_TUP : 0x0;
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uint32_t ctr = get_sign_counter();
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put_uint32_t_be(ctr, resp->ctr);
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uint8_t hash[32], sig_base[CTAP_APPID_SIZE + 1 + 4 + CTAP_CHAL_SIZE];
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memcpy(sig_base, req->appId, CTAP_APPID_SIZE);
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memcpy(sig_base + CTAP_APPID_SIZE, &resp->flags, sizeof(uint8_t));
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memcpy(sig_base + CTAP_APPID_SIZE + 1, resp->ctr, 4);
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memcpy(sig_base + CTAP_APPID_SIZE + 1 + 4, req->chal, CTAP_CHAL_SIZE);
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ret = mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), sig_base, sizeof(sig_base), hash);
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if (ret != 0) {
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mbedtls_ecp_keypair_free(&key);
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return SW_EXEC_ERROR();
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}
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size_t olen = 0;
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ret = mbedtls_ecdsa_write_signature(&key, MBEDTLS_MD_SHA256, hash, 32, (uint8_t *) resp->sig, CTAP_MAX_EC_SIG_SIZE, &olen, random_gen, NULL);
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mbedtls_ecp_keypair_free(&key);
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if (ret != 0) {
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return SW_EXEC_ERROR();
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}
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res_APDU_size = 1 + 4 + (uint16_t)olen;
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ctr++;
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file_put_data(ef_counter, (uint8_t *) &ctr, sizeof(ctr));
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low_flash_available();
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return SW_OK();
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}
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