Add hardware signing and key exporting

atecc608a_se.c

@@ -0,0 +1,242 @@
+/**
+ * \file atecc608a_se.c
+ * \brief Secure element driver implementation for ATECC508A and ATECC509A.
+ */
+
+/*
+ *  Copyright (C) 2019, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+#include "atecc608a_se.h"
+#include "atca_helpers.h"
+
+#ifdef DEBUG_PRINT
+#include <stdio.h>
+#endif
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/* Uncomment to print results on success */
+//#define DEBUG_PRINT
+
+/** This macro checks if the result of an `expression` is equal to an
+ *  `expected` value and sets a `status` variable of type `psa_status_t` to
+ *  `PSA_SUCCESS`. If they are not equal, the `status` is set to
+ *  `psa_error instead`, and the code jumps to the `exit` label. */
+#define ASSERT_STATUS(expression, expected, psa_error)          \
+    do                                                          \
+    {                                                           \
+        ATCA_STATUS ASSERT_result = (expression);               \
+        ATCA_STATUS ASSERT_expected = (expected);               \
+        if ((ASSERT_result) != (ASSERT_expected))               \
+        {                                                       \
+            status = (psa_error);                               \
+            goto exit;                                          \
+        }                                                       \
+        status = PSA_SUCCESS;                                   \
+    } while(0)
+
+/** Check if an ATCA operation is successful, translate the error otherwise. */
+#define ASSERT_SUCCESS(expression) ASSERT_STATUS(expression, ATCA_SUCCESS, \
+                                      atecc608a_to_psa_error(ASSERT_result))
+
+/** Does the same as the macro above, but without the error translation and for
+ *  the PSA return code - PSA_SUCCESS.*/
+#define ASSERT_SUCCESS_PSA(expression) ASSERT_STATUS(expression, PSA_SUCCESS, \
+                                                     ASSERT_result)
+
+static ATCAIfaceCfg atca_iface_config = {
+    .iface_type = ATCA_I2C_IFACE,
+    .devtype = ATECC608A,
+    .atcai2c.slave_address = 0xC0,
+    .atcai2c.bus = 2,
+    .atcai2c.baud = 400000,
+    .wake_delay = 1500,
+    .rx_retries = 20,
+};
+
+psa_status_t atecc608a_to_psa_error(ATCA_STATUS ret)
+{
+    switch (ret)
+    {
+    case ATCA_SUCCESS:
+    case ATCA_RX_NO_RESPONSE:
+    case ATCA_WAKE_SUCCESS:
+        return PSA_SUCCESS;
+    case ATCA_BAD_PARAM:
+    case ATCA_INVALID_ID:
+        return PSA_ERROR_INVALID_ARGUMENT;
+    case ATCA_ASSERT_FAILURE:
+        return PSA_ERROR_TAMPERING_DETECTED;
+    case ATCA_SMALL_BUFFER:
+        return PSA_ERROR_BUFFER_TOO_SMALL;
+    case ATCA_RX_CRC_ERROR:
+    case ATCA_RX_FAIL:
+    case ATCA_STATUS_CRC:
+    case ATCA_RESYNC_WITH_WAKEUP:
+    case ATCA_PARITY_ERROR:
+    case ATCA_TX_TIMEOUT:
+    case ATCA_RX_TIMEOUT:
+    case ATCA_TOO_MANY_COMM_RETRIES:
+    case ATCA_COMM_FAIL:
+    case ATCA_TIMEOUT:
+    case ATCA_TX_FAIL:
+    case ATCA_NO_DEVICES:
+        return PSA_ERROR_COMMUNICATION_FAILURE;
+    case ATCA_UNIMPLEMENTED:
+        return PSA_ERROR_NOT_SUPPORTED;
+    case ATCA_ALLOC_FAILURE:
+        return PSA_ERROR_INSUFFICIENT_MEMORY;
+    case ATCA_BAD_OPCODE:
+    case ATCA_CONFIG_ZONE_LOCKED:
+    case ATCA_DATA_ZONE_LOCKED:
+    case ATCA_NOT_LOCKED:
+    case ATCA_WAKE_FAILED:
+    case ATCA_STATUS_UNKNOWN:
+    case ATCA_STATUS_ECC:
+    case ATCA_STATUS_SELFTEST_ERROR:
+    case ATCA_CHECKMAC_VERIFY_FAILED:
+    case ATCA_PARSE_ERROR:
+    case ATCA_FUNC_FAIL:
+    case ATCA_GEN_FAIL:
+    case ATCA_EXECUTION_ERROR:
+    case ATCA_HEALTH_TEST_ERROR:
+    case ATCA_INVALID_SIZE:
+    default:
+        return PSA_ERROR_HARDWARE_FAILURE;
+    }
+}
+
+psa_status_t atecc608a_init()
+{
+    return atecc608a_to_psa_error(atcab_init(&atca_iface_config));
+}
+
+psa_status_t atecc608a_deinit()
+{
+    return atecc608a_to_psa_error(atcab_release());
+}
+
+static psa_status_t atecc608a_export_public_key(psa_key_slot_number_t key,
+                                                uint8_t *p_data, size_t data_size,
+                                                size_t *p_data_length)
+{
+    const size_t key_data_len = 65;
+    const uint16_t slot = key;
+    psa_status_t status = PSA_ERROR_GENERIC_ERROR;
+
+    if (data_size < key_data_len)
+    {
+        return PSA_ERROR_BUFFER_TOO_SMALL;
+    }
+
+    ASSERT_SUCCESS_PSA(atecc608a_init());
+
+    /* atcab_get_pubkey returns concatenated x and y values, and the desired
+       format is 0x04 + x + y. We start at &p_data[1] and add a 0x04 at p_data[0]. */
+    ASSERT_SUCCESS(atcab_get_pubkey(slot, &p_data[1]));
+
+    p_data[0] = 4;
+    *p_data_length = key_data_len;
+
+#ifdef DEBUG_PRINT
+    printf("atecc608a_export_key - pubkey size %d:\n", *p_data_length);
+    atcab_printbin_sp(p_data, *p_data_length);
+#endif
+
+exit:
+    atecc608a_deinit();
+    return status;
+}
+
+static psa_status_t atecc608a_asymmetric_sign(psa_key_slot_number_t key_slot,
+                                              psa_algorithm_t alg,
+                                              const uint8_t *p_hash,
+                                              size_t hash_length,
+                                              uint8_t *p_signature,
+                                              size_t signature_size,
+                                              size_t *p_signature_length)
+{
+    const uint16_t key_id = key_slot;
+    psa_status_t status = PSA_ERROR_GENERIC_ERROR;
+
+    /* We can only do ECDSA on SHA-256 */
+    if (alg != PSA_ALG_ECDSA(PSA_ALG_SHA_256) && alg != PSA_ALG_ECDSA_ANY)
+    {
+        return PSA_ERROR_NOT_SUPPORTED;
+    }
+
+    if (hash_length != 32)
+    {
+        /* The driver only supports signing things of length 32. */
+        return PSA_ERROR_NOT_SUPPORTED;
+    }
+
+    if (signature_size < ATCA_SIG_SIZE)
+    {
+        return PSA_ERROR_BUFFER_TOO_SMALL;
+    }
+
+    ASSERT_SUCCESS_PSA(atecc608a_init());
+
+    /* Signature will be returned here. Format is R and S integers in
+     * big-endian format. 64 bytes for P256 curve. */
+    ASSERT_SUCCESS(atcab_sign(key_id, p_hash, p_signature));
+
+    *p_signature_length = ATCA_SIG_SIZE;
+
+#ifdef DEBUG_PRINT
+    printf("atecc608a_asymmetric_sign - signature size %d:\n", *p_signature_length);
+    atcab_printbin_sp(p_signature, *p_signature_length);
+#endif
+
+exit:
+    atecc608a_deinit();
+    return status;
+}
+
+
+#define PSA_ATECC608A_LIFETIME 0xdeadbeefU
+
+static psa_drv_se_asymmetric_t atecc608a_asymmetric =
+{
+    .p_sign = &atecc608a_asymmetric_sign,
+    .p_verify = 0,
+    .p_encrypt = 0,
+    .p_decrypt = 0,
+};
+
+static psa_drv_se_key_management_t atecc608a_key_management =
+{
+    .p_import = 0,
+    .p_generate = 0,
+    .p_destroy = 0,
+    /* So far there is no public key export function in the API, so use this instead */
+    .p_export = &atecc608a_export_public_key,
+};
+
+psa_drv_se_info_t atecc608a_drv_info =
+{
+    .lifetime = PSA_ATECC608A_LIFETIME,
+    .p_key_management = &atecc608a_key_management,
+    .p_mac = 0,
+    .p_cipher = 0,
+    .p_asym = &atecc608a_asymmetric,
+    .p_aead = 0,
+    .p_derive = 0,
+    .slot_min = 0,
+    .slot_max = 0,
+};

atecc608a_se.h

@@ -0,0 +1,37 @@
+/**
+ * \file atecc608a_se.h
+ * \brief Secure element driver structure for ATECC508A and ATECC509A.
+ */
+
+/*
+ *  Copyright (C) 2019, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef ATECC608A_SE_H
+#define ATECC608A_SE_H
+
+#include "psa/crypto_se_driver.h"
+#include "atca_basic.h"
+
+extern psa_drv_se_info_t atecc608a_drv_info;
+
+psa_status_t atecc608a_to_psa_error(ATCA_STATUS ret);
+
+psa_status_t atecc608a_init();
+
+psa_status_t atecc608a_deinit();
+
+#endif /* ATECC608A_SE_H */