195 lines
6.9 KiB
C
195 lines
6.9 KiB
C
/*
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* This file is part of the Pico HSM distribution (https://github.com/polhenarejos/pico-hsm).
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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 "common.h"
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#include "mbedtls/ecdh.h"
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#include "crypto_utils.h"
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#include "sc_hsm.h"
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#include "kek.h"
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#include "files.h"
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#include "asn1.h"
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#include "cvc.h"
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#include "random.h"
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#include "oid.h"
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int cmd_decrypt_asym() {
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int key_id = P1(apdu);
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uint8_t p2 = P2(apdu);
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if (!isUserAuthenticated) {
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return SW_SECURITY_STATUS_NOT_SATISFIED();
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}
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file_t *ef = search_dynamic_file((KEY_PREFIX << 8) | key_id);
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if (!ef) {
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return SW_FILE_NOT_FOUND();
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}
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if (get_key_counter(ef) == 0) {
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return SW_FILE_FULL();
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}
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if (key_has_purpose(ef, p2) == false) {
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return SW_CONDITIONS_NOT_SATISFIED();
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}
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if (p2 >= ALGO_RSA_DECRYPT && p2 <= ALGO_RSA_DECRYPT_OEP) {
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mbedtls_rsa_context ctx;
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mbedtls_rsa_init(&ctx);
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if (p2 == ALGO_RSA_DECRYPT_OEP) {
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mbedtls_rsa_set_padding(&ctx, MBEDTLS_RSA_PKCS_V21, MBEDTLS_MD_SHA256);
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}
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int r = load_private_key_rsa(&ctx, ef);
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if (r != CCID_OK) {
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mbedtls_rsa_free(&ctx);
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if (r == CCID_VERIFICATION_FAILED) {
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return SW_SECURE_MESSAGE_EXEC_ERROR();
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}
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return SW_EXEC_ERROR();
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}
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int key_size = file_get_size(ef);
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if (apdu.nc < key_size) { //needs padding
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memset(apdu.data + apdu.nc, 0, key_size - apdu.nc);
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}
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if (p2 == ALGO_RSA_DECRYPT_PKCS1 || p2 == ALGO_RSA_DECRYPT_OEP) {
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size_t olen = apdu.nc;
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r = mbedtls_rsa_pkcs1_decrypt(&ctx, random_gen, NULL, &olen, apdu.data, res_APDU, 512);
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if (r == 0) {
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res_APDU_size = olen;
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}
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}
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else {
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r = mbedtls_rsa_private(&ctx, random_gen, NULL, apdu.data, res_APDU);
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if (r == 0) {
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res_APDU_size = key_size;
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}
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}
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if (r != 0) {
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mbedtls_rsa_free(&ctx);
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return SW_EXEC_ERROR();
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}
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mbedtls_rsa_free(&ctx);
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}
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else if (p2 == ALGO_EC_DH || p2 == ALGO_EC_DH_XKEK) {
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mbedtls_ecdh_context ctx;
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if (wait_button_pressed() == true) { //timeout
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return SW_SECURE_MESSAGE_EXEC_ERROR();
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}
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int key_size = file_get_size(ef);
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uint8_t *kdata = (uint8_t *) calloc(1, key_size);
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memcpy(kdata, file_get_data(ef), key_size);
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if (mkek_decrypt(kdata, key_size) != 0) {
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mbedtls_platform_zeroize(kdata, key_size);
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free(kdata);
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return SW_EXEC_ERROR();
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}
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mbedtls_ecdh_init(&ctx);
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mbedtls_ecp_group_id gid = kdata[0];
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int r = 0;
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r = mbedtls_ecdh_setup(&ctx, gid);
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if (r != 0) {
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mbedtls_platform_zeroize(kdata, key_size);
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mbedtls_ecdh_free(&ctx);
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free(kdata);
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return SW_DATA_INVALID();
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}
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r = mbedtls_mpi_read_binary(&ctx.ctx.mbed_ecdh.d, kdata + 1, key_size - 1);
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mbedtls_platform_zeroize(kdata, key_size);
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free(kdata);
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if (r != 0) {
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mbedtls_ecdh_free(&ctx);
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return SW_DATA_INVALID();
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}
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r = -1;
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if (p2 == ALGO_EC_DH) {
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r = mbedtls_ecdh_read_public(&ctx, apdu.data - 1, apdu.nc + 1);
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}
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else if (p2 == ALGO_EC_DH_XKEK) {
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size_t pub_len = 0;
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const uint8_t *pub = cvc_get_pub(apdu.data, apdu.nc, &pub_len);
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if (pub) {
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size_t t86_len = 0;
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const uint8_t *t86 = cvc_get_field(pub, pub_len, &t86_len, 0x86);
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if (t86) {
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r = mbedtls_ecdh_read_public(&ctx, t86 - 1, t86_len + 1);
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}
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}
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}
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if (r != 0) {
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mbedtls_ecdh_free(&ctx);
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return SW_DATA_INVALID();
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}
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size_t olen = 0;
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r =
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mbedtls_ecdh_calc_secret(&ctx, &olen, res_APDU, MBEDTLS_ECP_MAX_BYTES, random_gen,
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NULL);
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mbedtls_ecdh_free(&ctx);
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if (r != 0) {
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return SW_EXEC_ERROR();
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}
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if (p2 == ALGO_EC_DH) {
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res_APDU_size = olen;
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}
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else {
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res_APDU_size = 0;
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size_t ext_len = 0;
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const uint8_t *ext = NULL;
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if ((ext = cvc_get_ext(apdu.data, apdu.nc, &ext_len)) == NULL) {
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return SW_WRONG_DATA();
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}
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uint8_t *p = NULL, *tag_data = NULL, *kdom_uid = NULL;
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uint16_t tag = 0;
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size_t tag_len = 0, kdom_uid_len = 0;
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while (walk_tlv(ext, ext_len, &p, &tag, &tag_len, &tag_data)) {
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if (tag == 0x73) {
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size_t oid_len = 0;
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uint8_t *oid_data = NULL;
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if (asn1_find_tag(tag_data, tag_len, 0x6, &oid_len,
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&oid_data) == true &&
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oid_len == strlen(OID_ID_KEY_DOMAIN_UID) &&
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memcmp(oid_data, OID_ID_KEY_DOMAIN_UID,
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strlen(OID_ID_KEY_DOMAIN_UID)) == 0) {
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if (asn1_find_tag(tag_data, tag_len, 0x80, &kdom_uid_len,
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&kdom_uid) == false) {
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return SW_WRONG_DATA();
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}
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break;
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}
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}
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}
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if (kdom_uid_len == 0 || kdom_uid == NULL) {
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return SW_WRONG_DATA();
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}
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for (int n = 0; n < MAX_KEY_DOMAINS; n++) {
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file_t *tf = search_dynamic_file(EF_XKEK + n);
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if (tf) {
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if (file_get_size(tf) == kdom_uid_len &&
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memcmp(file_get_data(tf), kdom_uid, kdom_uid_len) == 0) {
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file_new(EF_DKEK + n);
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if (store_dkek_key(n, res_APDU) != CCID_OK) {
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return SW_EXEC_ERROR();
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}
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mbedtls_platform_zeroize(res_APDU, 32);
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return SW_OK();
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}
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}
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}
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return SW_REFERENCE_NOT_FOUND();
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}
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}
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else {
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return SW_WRONG_P1P2();
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}
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decrement_key_counter(ef);
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return SW_OK();
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}
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