394 lines
15 KiB
C
394 lines
15 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 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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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "cbor.h"
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#include "ctap.h"
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#include "ctap2_cbor.h"
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#include "bsp/board.h"
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#include "fido.h"
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#include "files.h"
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#include "random.h"
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#include "crypto_utils.h"
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#include "hsm.h"
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#include "apdu.h"
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#include "cbor_make_credential.h"
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#include "credential.h"
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#include <math.h>
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CborCharString rpIdx = {0};
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CborByteString pinUvAuthParamx = {0}, clientDataHashx = {0};
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bool residentx = false;
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Credential credsx[MAX_CREDENTIAL_COUNT_IN_LIST] = {0};
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uint64_t pinUvAuthProtocolx = 0;
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CredExtensions extensionx = {0};
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CredOptions optionsx = {0};
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uint8_t flagsx = 0;
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uint8_t credentialCounter = 1;
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uint8_t numberOfCredentialsx = 0;
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int cbor_get_assertion(const uint8_t *data, size_t len) {
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size_t resp_size = 0;
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uint64_t pinUvAuthProtocol = 0;
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CredOptions options = {0};
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CredExtensions extensions = {0};
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CborParser parser;
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CborEncoder encoder, mapEncoder, mapEncoder2;
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CborValue map;
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CborError error = CborNoError;
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CborByteString pinUvAuthParam = {0}, clientDataHash = {0};
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CborCharString rpId = {0};
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PublicKeyCredentialDescriptor allowList[MAX_CREDENTIAL_COUNT_IN_LIST] = {0};
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Credential creds[MAX_CREDENTIAL_COUNT_IN_LIST] = {0};
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size_t allowList_len = 0, creds_len = 0;
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uint8_t *aut_data = NULL;
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bool asserted = false;
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CBOR_CHECK(cbor_parser_init(data, len, 0, &parser, &map));
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uint64_t val_c = 1;
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CBOR_PARSE_MAP_START(map, 1) {
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uint64_t val_u = 0;
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CBOR_FIELD_GET_UINT(val_u, 1);
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if (val_c <= 2 && val_c != val_u)
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CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
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if (val_u < val_c)
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CBOR_ERROR(CTAP2_ERR_INVALID_CBOR);
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val_c = val_u + 1;
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if (val_u == 0x01) {
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CBOR_FIELD_GET_TEXT(rpId, 1);
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}
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else if (val_u == 0x02) {
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CBOR_FIELD_GET_BYTES(clientDataHash, 1);
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}
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else if (val_u == 0x03) { // excludeList
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CBOR_PARSE_ARRAY_START(_f1, 2) {
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PublicKeyCredentialDescriptor *pc = &allowList[allowList_len];
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CBOR_PARSE_MAP_START(_f2, 3) {
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CBOR_FIELD_GET_KEY_TEXT(3);
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CBOR_FIELD_KEY_TEXT_VAL_BYTES(3, "id", pc->id);
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CBOR_FIELD_KEY_TEXT_VAL_TEXT(3, "type", pc->type);
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if (strcmp(_fd3, "transports") == 0) {
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CBOR_PARSE_ARRAY_START(_f3, 4) {
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CBOR_FIELD_GET_TEXT(pc->transports[pc->transports_len], 4);
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pc->transports_len++;
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}
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CBOR_PARSE_ARRAY_END(_f3, 4);
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}
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}
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CBOR_PARSE_MAP_END(_f2, 3);
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allowList_len++;
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}
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CBOR_PARSE_ARRAY_END(_f1, 2);
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}
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else if (val_u == 0x04) { // extensions
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CBOR_PARSE_MAP_START(_f1, 2) {
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CBOR_FIELD_GET_KEY_TEXT(2);
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CBOR_FIELD_KEY_TEXT_VAL_BOOL(2, "hmac-secret", extensions.hmac_secret);
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CBOR_FIELD_KEY_TEXT_VAL_UINT(2, "credProtect", extensions.credProtect);
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CBOR_ADVANCE(2);
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}
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CBOR_PARSE_MAP_END(_f1, 2);
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}
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else if (val_u == 0x05) { // options
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options.present = true;
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CBOR_PARSE_MAP_START(_f1, 2) {
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CBOR_FIELD_GET_KEY_TEXT(2);
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CBOR_FIELD_KEY_TEXT_VAL_BOOL(2, "rk", options.rk);
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CBOR_FIELD_KEY_TEXT_VAL_BOOL(2, "up", options.up);
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CBOR_FIELD_KEY_TEXT_VAL_BOOL(2, "uv", options.uv);
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CBOR_ADVANCE(2);
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}
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CBOR_PARSE_MAP_END(_f1, 2);
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}
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else if (val_u == 0x06) { // pinUvAuthParam
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CBOR_FIELD_GET_BYTES(pinUvAuthParam, 1);
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}
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else if (val_u == 0x07) { // pinUvAuthProtocol
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CBOR_FIELD_GET_UINT(pinUvAuthProtocol, 1);
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}
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}
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CBOR_PARSE_MAP_END(map, 1);
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uint8_t flags = FIDO2_AUT_FLAG_AT;
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uint8_t rp_id_hash[32];
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mbedtls_sha256((uint8_t *)rpId.data, rpId.len, rp_id_hash, 0);
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if (pinUvAuthParam.present == true) {
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if (pinUvAuthParam.len == 0 || pinUvAuthParam.data == NULL) {
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if (check_user_presence() == false)
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CBOR_ERROR(CTAP2_ERR_OPERATION_DENIED);
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if (!file_has_data(ef_pin))
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CBOR_ERROR(CTAP2_ERR_PIN_NOT_SET);
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else
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CBOR_ERROR(CTAP2_ERR_PIN_AUTH_INVALID);
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}
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else {
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if (pinUvAuthProtocol == 0)
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CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
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if (pinUvAuthProtocol != 1 && pinUvAuthProtocol != 2)
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CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
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}
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}
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if (options.present) {
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if (options.uv == ptrue) { //4.3
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CBOR_ERROR(CTAP2_ERR_INVALID_OPTION);
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}
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//if (options.up != NULL) { //4.5
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// CBOR_ERROR(CTAP2_ERR_INVALID_OPTION);
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//}
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if (options.rk != NULL) {
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CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION);
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}
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//else if (options.up == NULL) //5.7
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//rup = ptrue;
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}
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if (pinUvAuthParam.present == true) { //6.1
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int ret = verify(pinUvAuthProtocol, paut.data, clientDataHash.data, clientDataHash.len, pinUvAuthParam.data);
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if (ret != CborNoError)
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CBOR_ERROR(CTAP2_ERR_PIN_AUTH_INVALID);
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if (getUserVerifiedFlagValue() == false)
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CBOR_ERROR(CTAP2_ERR_PIN_AUTH_INVALID);
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flags |= FIDO2_AUT_FLAG_UV;
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// Check pinUvAuthToken permissions. See 6.2.2.4
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}
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bool resident = false;
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if (allowList_len > 0)
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{
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for (int e = 0; e < allowList_len; e++) {
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if (allowList[e].type.present == false || allowList[e].id.present == false)
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CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
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if (strcmp(allowList[e].type.data, "public-key") != 0)
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continue;
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if (credential_load(allowList[e].id.data, allowList[e].id.len, rp_id_hash, &creds[e]) != 0)
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CBOR_FREE_BYTE_STRING(allowList[e].id);
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}
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creds_len = allowList_len;
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}
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else {
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for (int i = 0; i < MAX_RESIDENT_CREDENTIALS && creds_len < MAX_CREDENTIAL_COUNT_IN_LIST; i++) {
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file_t *ef = search_dynamic_file(EF_CRED + i);
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if (!file_has_data(ef) || memcmp(file_get_data(ef), rp_id_hash, 32) != 0)
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continue;
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int ret = credential_load(file_get_data(ef) + 32, file_get_size(ef) - 32, rp_id_hash, &creds[creds_len]);
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if (ret != 0)
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credential_free(&creds[creds_len]);
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else
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creds_len++;
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}
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resident = true;
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}
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uint8_t numberOfCredentials = 0;
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for (int i = 0; i < creds_len; i++) {
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if (creds[i].present == true) {
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if (creds[i].extensions.present == true) {
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if (creds[i].extensions.credProtect == CRED_PROT_UV_REQUIRED && !(flags & FIDO2_AUT_FLAG_UV))
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credential_free(&creds[i]);
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else if (creds[i].extensions.credProtect == CRED_PROT_UV_OPTIONAL_WITH_LIST && resident == true && !(flags & FIDO2_AUT_FLAG_UV))
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credential_free(&creds[i]);
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else
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numberOfCredentials++;
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}
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else
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numberOfCredentials++;
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}
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}
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if (numberOfCredentials == 0)
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CBOR_ERROR(CTAP2_ERR_NO_CREDENTIALS);
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if (options.up == ptrue || options.present == false || options.up == NULL) { //9.1
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if (pinUvAuthParam.present == true) {
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if (getUserPresentFlagValue() == false) {
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if (check_user_presence() == false)
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CBOR_ERROR(CTAP2_ERR_OPERATION_DENIED);
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}
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}
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flags |= FIDO2_AUT_FLAG_UP;
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clearUserPresentFlag();
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clearUserVerifiedFlag();
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clearPinUvAuthTokenPermissionsExceptLbw();
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}
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if (numberOfCredentials == 0)
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CBOR_ERROR(CTAP2_ERR_NO_CREDENTIALS);
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Credential *selcred = NULL;
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if (resident == false) {
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selcred = &creds[0];
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}
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else {
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if (numberOfCredentials == 1)
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selcred = &creds[0];
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else {
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asserted = true;
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rpIdx = rpId;
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pinUvAuthParamx = pinUvAuthParamx;
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clientDataHashx = clientDataHash;
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residentx = resident;
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for (int i = 0; i < MAX_CREDENTIAL_COUNT_IN_LIST; i++)
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credsx[i] = creds[i];
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numberOfCredentialsx = numberOfCredentials;
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pinUvAuthProtocolx = pinUvAuthProtocol;
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extensionx = extensions;
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optionsx = options;
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flagsx = flags;
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}
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}
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uint8_t cred_id[MAX_CRED_ID_LENGTH];
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size_t cred_id_len = 0;
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if (credential_create_cred(selcred, cred_id, &cred_id_len) != 0)
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CBOR_ERROR(CTAP2_ERR_INTEGRITY_FAILURE);
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mbedtls_ecdsa_context ekey;
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mbedtls_ecdsa_init(&ekey);
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int ret = fido_load_key(selcred->curve, cred_id, &ekey);
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if (ret != 0) {
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mbedtls_ecdsa_free(&ekey);
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CBOR_ERROR(CTAP1_ERR_OTHER);
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}
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size_t ext_len = 0;
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uint8_t ext [512];
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if (extensions.present == true) {
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cbor_encoder_init(&encoder, ext, sizeof(ext), 0);
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int l = 0;
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if (extensions.hmac_secret != NULL)
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l++;
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if (extensions.credProtect != 0)
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l++;
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CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, l));
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if (extensions.credProtect != 0) {
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CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder, "credProtect"));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, extensions.credProtect));
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}
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if (extensions.hmac_secret != NULL) {
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CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder, "hmac-secret"));
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CBOR_CHECK(cbor_encode_boolean(&mapEncoder, *extensions.hmac_secret));
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}
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CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder));
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ext_len = cbor_encoder_get_buffer_size(&encoder, ext);
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flags |= FIDO2_AUT_FLAG_ED;
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}
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uint8_t pkey[66];
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const mbedtls_ecp_curve_info *cinfo = mbedtls_ecp_curve_info_from_grp_id(ekey.grp.id);
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if (cinfo == NULL)
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CBOR_ERROR(CTAP1_ERR_OTHER);
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size_t olen = 0, pkey_len = ceil((float)cinfo->bit_size/8);
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uint32_t ctr = *(uint32_t *)file_get_data(ef_counter);
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uint8_t cbor_buf[1024];
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cbor_encoder_init(&encoder, cbor_buf, sizeof(cbor_buf), 0);
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CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 5));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 1));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 2));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 3));
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CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, -selcred->alg));
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CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, 1));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, selcred->curve));
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CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, 2));
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mbedtls_mpi_write_binary(&ekey.Q.X, pkey, pkey_len);
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CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, pkey, pkey_len));
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CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, 3));
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mbedtls_mpi_write_binary(&ekey.Q.Y, pkey, pkey_len);
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CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, pkey, pkey_len));
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CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder));
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size_t rs = cbor_encoder_get_buffer_size(&encoder, cbor_buf);
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size_t aut_data_len = 32 + 1 + 4 + (16 + 2 + cred_id_len + rs) + ext_len;
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aut_data = (uint8_t *)calloc(1, aut_data_len + clientDataHash.len);
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uint8_t *pa = aut_data;
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memcpy(pa, rp_id_hash, 32); pa += 32;
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*pa++ = flags;
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*pa++ = ctr >> 24;
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*pa++ = ctr >> 16;
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*pa++ = ctr >> 8;
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*pa++ = ctr & 0xff;
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memcpy(pa, aaguid, 16); pa += 16;
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*pa++ = cred_id_len >> 8;
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*pa++ = cred_id_len & 0xff;
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memcpy(pa, cred_id, cred_id_len); pa += cred_id_len;
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memcpy(pa, cbor_buf, rs); pa += rs;
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memcpy(pa, ext, ext_len); pa += ext_len;
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if (pa-aut_data != aut_data_len)
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CBOR_ERROR(CTAP1_ERR_OTHER);
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memcpy(pa, clientDataHash.data, clientDataHash.len);
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uint8_t hash[32], sig[MBEDTLS_ECDSA_MAX_LEN];
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ret = mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), aut_data, aut_data_len+clientDataHash.len, hash);
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ret = mbedtls_ecdsa_write_signature(&ekey, MBEDTLS_MD_SHA256, hash, 32, sig, sizeof(sig), &olen, random_gen, NULL);
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mbedtls_ecdsa_free(&ekey);
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uint8_t lfields = 3;
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if (resident)
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lfields++;
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if (numberOfCredentials > 1)
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lfields++;
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cbor_encoder_init(&encoder, ctap_resp->init.data + 1, CTAP_MAX_PACKET_SIZE, 0);
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CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, lfields));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01));
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CBOR_CHECK(cbor_encoder_create_map(&mapEncoder, &mapEncoder2, 2));
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CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "type"));
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CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "public-key"));
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CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "id"));
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CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, cred_id, cred_id_len));
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CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x02));
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CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, aut_data, aut_data_len));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x03));
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CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, sig, olen));
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if (resident) {
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x04));
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CBOR_CHECK(cbor_encoder_create_map(&mapEncoder, &mapEncoder2, 1));
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CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "id"));
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CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, selcred->userId.data, selcred->userId.len));
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CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2));
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}
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if (numberOfCredentials > 1) {
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x05));
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CBOR_CHECK(cbor_encode_uint(&mapEncoder, numberOfCredentials));
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}
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CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder));
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res_APDU_size = cbor_encoder_get_buffer_size(&encoder, ctap_resp->init.data + 1);
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err:
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if (asserted == false) {
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CBOR_FREE_BYTE_STRING(clientDataHash);
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CBOR_FREE_BYTE_STRING(pinUvAuthParam);
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CBOR_FREE_BYTE_STRING(rpId);
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}
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for (int m = 0; m < allowList_len; m++) {
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CBOR_FREE_BYTE_STRING(allowList[m].type);
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CBOR_FREE_BYTE_STRING(allowList[m].id);
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for (int n = 0; n < allowList[m].transports_len; n++) {
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CBOR_FREE_BYTE_STRING(allowList[m].transports[n]);
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}
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}
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if (aut_data)
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free(aut_data);
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if (error != CborNoError) {
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if (error == CborErrorImproperValue)
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return CTAP2_ERR_CBOR_UNEXPECTED_TYPE;
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return error;
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}
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res_APDU_size = resp_size;
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return 0;
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}
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