Sarah Marsh / Mbed OS EddystoneBeacon

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source/EntropySource/nRFEntropySource/nRFEntropySource.cpp@0:1c7da5f83647, 2016-11-29 (annotated)

Committer:
sarahmarshy
Date:
Tue Nov 29 06:29:10 2016 +0000
Revision:
0:1c7da5f83647
Initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sarahmarshy 0:1c7da5f83647 1 /* mbed Microcontroller Library
sarahmarshy 0:1c7da5f83647 2 * Copyright (c) 2006-2015 ARM Limited
sarahmarshy 0:1c7da5f83647 3 *
sarahmarshy 0:1c7da5f83647 4 * Licensed under the Apache License, Version 2.0 (the "License");
sarahmarshy 0:1c7da5f83647 5 * you may not use this file except in compliance with the License.
sarahmarshy 0:1c7da5f83647 6 * You may obtain a copy of the License at
sarahmarshy 0:1c7da5f83647 7 *
sarahmarshy 0:1c7da5f83647 8 * http://www.apache.org/licenses/LICENSE-2.0
sarahmarshy 0:1c7da5f83647 9 *
sarahmarshy 0:1c7da5f83647 10 * Unless required by applicable law or agreed to in writing, software
sarahmarshy 0:1c7da5f83647 11 * distributed under the License is distributed on an "AS IS" BASIS,
sarahmarshy 0:1c7da5f83647 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
sarahmarshy 0:1c7da5f83647 13 * See the License for the specific language governing permissions and
sarahmarshy 0:1c7da5f83647 14 * limitations under the License.
sarahmarshy 0:1c7da5f83647 15 */
sarahmarshy 0:1c7da5f83647 16 #include "../EntropySource.h"
sarahmarshy 0:1c7da5f83647 17
sarahmarshy 0:1c7da5f83647 18 #if defined(TARGET_NRF51822) || defined(TARGET_MCU_NRF52832) /* Persistent storage supported on nrf51 platforms */
sarahmarshy 0:1c7da5f83647 19
sarahmarshy 0:1c7da5f83647 20 #include "nrf_soc.h"
sarahmarshy 0:1c7da5f83647 21 #include "nrf_error.h"
sarahmarshy 0:1c7da5f83647 22 #include "mbed.h"
sarahmarshy 0:1c7da5f83647 23 #include <mbedtls/entropy.h>
sarahmarshy 0:1c7da5f83647 24
sarahmarshy 0:1c7da5f83647 25 /*
sarahmarshy 0:1c7da5f83647 26 * nRF51 has a TRNG that we can access using SoftDevice.
sarahmarshy 0:1c7da5f83647 27 */
sarahmarshy 0:1c7da5f83647 28 int eddystoneEntropyPoll(void *data, unsigned char *output, size_t len, size_t *olen)
sarahmarshy 0:1c7da5f83647 29 {
sarahmarshy 0:1c7da5f83647 30 uint8_t bytes_available = 0;
sarahmarshy 0:1c7da5f83647 31
sarahmarshy 0:1c7da5f83647 32 // get the number of random bytes available
sarahmarshy 0:1c7da5f83647 33 if (sd_rand_application_bytes_available_get(&bytes_available) != NRF_SUCCESS) {
sarahmarshy 0:1c7da5f83647 34 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
sarahmarshy 0:1c7da5f83647 35 }
sarahmarshy 0:1c7da5f83647 36
sarahmarshy 0:1c7da5f83647 37 // if there is more bytes available that what is requested,
sarahmarshy 0:1c7da5f83647 38 // truncate the number of bytes in output to len, otherwise use the total
sarahmarshy 0:1c7da5f83647 39 // of bytes available.
sarahmarshy 0:1c7da5f83647 40 const uint8_t output_len = bytes_available > len ? len : bytes_available;
sarahmarshy 0:1c7da5f83647 41
sarahmarshy 0:1c7da5f83647 42 if (output_len) {
sarahmarshy 0:1c7da5f83647 43 // transfer "output_len" random bytes to output.
sarahmarshy 0:1c7da5f83647 44 if (sd_rand_application_vector_get(output, output_len) != NRF_SUCCESS) {
sarahmarshy 0:1c7da5f83647 45 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
sarahmarshy 0:1c7da5f83647 46 }
sarahmarshy 0:1c7da5f83647 47 }
sarahmarshy 0:1c7da5f83647 48
sarahmarshy 0:1c7da5f83647 49 // Everything went fine, commit the output_len to the output parameter
sarahmarshy 0:1c7da5f83647 50 *olen = output_len;
sarahmarshy 0:1c7da5f83647 51 return 0;
sarahmarshy 0:1c7da5f83647 52 }
sarahmarshy 0:1c7da5f83647 53
sarahmarshy 0:1c7da5f83647 54 int eddystoneRegisterEntropySource( mbedtls_entropy_context* ctx) {
sarahmarshy 0:1c7da5f83647 55 uint8_t pool_capacity;
sarahmarshy 0:1c7da5f83647 56 sd_rand_application_pool_capacity_get(&pool_capacity);
sarahmarshy 0:1c7da5f83647 57
sarahmarshy 0:1c7da5f83647 58 return mbedtls_entropy_add_source(
sarahmarshy 0:1c7da5f83647 59 ctx,
sarahmarshy 0:1c7da5f83647 60 eddystoneEntropyPoll, // entropy source function
sarahmarshy 0:1c7da5f83647 61 NULL, // entropy source data, NULL in this case
sarahmarshy 0:1c7da5f83647 62 pool_capacity, // minimum number of bytes the entropy pool should wait on from this callback before releasing entropy
sarahmarshy 0:1c7da5f83647 63 MBEDTLS_ENTROPY_SOURCE_STRONG
sarahmarshy 0:1c7da5f83647 64 );
sarahmarshy 0:1c7da5f83647 65 }
sarahmarshy 0:1c7da5f83647 66
sarahmarshy 0:1c7da5f83647 67 #endif /* #ifdef TARGET_NRF51822 */