mirror of
https://github.com/Lurkars/esp-ena.git
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96 lines
3.0 KiB
C
96 lines
3.0 KiB
C
// Copyright 2020 Lukas Haubaum
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//
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// Licensed under the GNU Affero General Public License, Version 3;
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// https://www.gnu.org/licenses/agpl-3.0.html
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "mbedtls/md.h"
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#include "mbedtls/aes.h"
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#include "mbedtls/hkdf.h"
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#include "mbedtls/entropy.h"
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#include "mbedtls/ctr_drbg.h"
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#include "esp_log.h"
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#include "ena-crypto.h"
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#define ESP_CRYPTO_LOG "ESP-CRYPTO"
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static mbedtls_ctr_drbg_context ctr_drbg;
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void ena_crypto_init(void)
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{
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mbedtls_entropy_context entropy;
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uint8_t pers[] = "Exposure Notifcation API esp32";
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int ret;
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mbedtls_entropy_init(&entropy);
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mbedtls_ctr_drbg_init(&ctr_drbg);
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if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, pers, sizeof(pers))) != 0)
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{
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ESP_LOGE(ESP_CRYPTO_LOG, " failed\n ! mbedtls_ctr_drbg_init returned -0x%04x\n", -ret);
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}
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}
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uint32_t ena_crypto_enin(uint32_t unix_epoch_time)
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{
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return unix_epoch_time / ENA_TIME_WINDOW;
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}
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void ena_crypto_tek(uint8_t *tek)
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{
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int ret;
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if ((ret = mbedtls_ctr_drbg_random(&ctr_drbg, tek, ENA_KEY_LENGTH)) != 0)
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{
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ESP_LOGE(ESP_CRYPTO_LOG, " failed\n ! mbedtls_ctr_drbg_random returned -0x%04x\n", -ret);
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}
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}
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void ena_crypto_rpik(uint8_t *rpik, uint8_t *tek)
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{
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const uint8_t rpik_info[] = "EN-RPIK";
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mbedtls_hkdf(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), NULL, 0, tek, ENA_KEY_LENGTH, rpik_info, sizeof(rpik_info), rpik, ENA_KEY_LENGTH);
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}
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void ena_crypto_rpi(uint8_t *rpi, uint8_t *rpik, uint32_t enin)
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{
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uint8_t padded_data[] = "EN-RPI";
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padded_data[12] = (enin & 0x000000ff);
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padded_data[13] = (enin & 0x0000ff00) >> 8;
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padded_data[14] = (enin & 0x00ff0000) >> 16;
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padded_data[15] = (enin & 0xff000000) >> 24;
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mbedtls_aes_context aes;
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mbedtls_aes_init(&aes);
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mbedtls_aes_setkey_enc(&aes, rpik, ENA_KEY_LENGTH * 8);
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mbedtls_aes_crypt_ecb(&aes, MBEDTLS_AES_ENCRYPT, padded_data, rpi);
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mbedtls_aes_free(&aes);
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}
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void ena_crypto_aemk(uint8_t *aemk, uint8_t *tek)
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{
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uint8_t aemkInfo[] = "EN-AEMK";
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mbedtls_hkdf(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), NULL, 0, tek, ENA_KEY_LENGTH, aemkInfo, sizeof(aemkInfo), aemk, ENA_KEY_LENGTH);
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}
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void ena_crypto_aem(uint8_t *aem, uint8_t *aemk, uint8_t *rpi, uint8_t power_level)
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{
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uint8_t metadata[ENA_AEM_METADATA_LENGTH];
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metadata[0] = 0b01000000;
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metadata[1] = power_level;
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size_t count = 0;
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uint8_t sb[16] = {0};
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mbedtls_aes_context aes;
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mbedtls_aes_init(&aes);
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mbedtls_aes_setkey_enc(&aes, aemk, ENA_KEY_LENGTH * 8);
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mbedtls_aes_crypt_ctr(&aes, ENA_AEM_METADATA_LENGTH, &count, rpi, sb, metadata, aem);
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mbedtls_aes_free(&aes);
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} |