Merge pull request #3 from deepikabhavnani/device_key

DeviceKey example added

Author: Cruz Monrreal

DeviceKey/main.cpp

@@ -0,0 +1,86 @@
+/*
+* Copyright (c) 2018 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 "mbed.h"
+#include "DeviceKey.h"
+
+// Print a unsigned char buffer in hex format
+void print_buffer(unsigned char *buf, size_t size)
+{
+    for (size_t i = 0; i < size; i++) {
+        printf("%02X", buf[i]);
+    }
+}
+
+// Injection of a dummy key when there is no TRNG
+int inject_rot_key()
+{
+    uint32_t key[DEVICE_KEY_16BYTE / sizeof(uint32_t)];
+
+    memset(key, 0, DEVICE_KEY_16BYTE);
+    memcpy(key, "ABCDEF1234567890", DEVICE_KEY_16BYTE);
+    int size = DEVICE_KEY_16BYTE;
+    DeviceKey& devkey = DeviceKey::get_instance();
+    return devkey.device_inject_root_of_trust(key, size);
+}
+
+// Entry point for the example
+int main()
+{
+    unsigned char derive_key1 [DEVICE_KEY_32BYTE];
+    unsigned char salt1[] = "SALT1 ----- SALT1 ------ SALT1";
+    int ret = DEVICEKEY_SUCCESS;
+
+    printf("\nMbed OS DeviceKey example \n");
+
+    // DeviceKey is a singleton
+    DeviceKey& devkey = DeviceKey::get_instance();
+
+#if !defined(DEVICE_TRNG)
+
+    // If TRNG is not available it is a must to inject the ROT before the first call to derive key method.
+    printf("No TRNG support for this device. injecting ROT.\n");
+    ret = inject_rot_key();
+    if (DEVICEKEY_SUCCESS != ret && DEVICEKEY_ALREADY_EXIST != ret) {
+        printf("Error, injection of ROT key has failed with status %d\n", ret);
+        return -1;
+    }
+
+    if ( DEVICEKEY_ALREADY_EXIST == ret ) {
+        printf("ROT Key already exists in the persistent memory.\n", ret);
+    } else {
+        printf("ROT Key injected and stored in persistent memory.\n", ret);
+    }
+
+#endif
+
+    printf("Salt for key derivation: %s \n", salt1);
+
+    // 16 byte key derivation.
+    ret = devkey.generate_derived_key(salt1, sizeof(salt1), derive_key1, DEVICE_KEY_16BYTE);
+    if (DEVICEKEY_SUCCESS != ret) {
+        printf("Error, derive key failed with error code %d \n", ret);
+        return -1;
+    }
+
+    printf("16-byte Derived key is: ");
+    print_buffer(derive_key1, DEVICE_KEY_16BYTE);
+    printf("\n");
+
+    printf("Mbed OS DeviceKey example done.\n");
+
+    return 0;
+}

DeviceKey/mbed-os.lib

@@ -0,0 +1 @@
+https://github.com/ARMmbed/mbed-os/#c53d51fe9220728bf8ed27afe7afc1ecc3f6f5d7