1 /*
2 * Copyright (c) 2001-2019, Arm Limited and Contributors. All rights reserved.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7
8
9 /************* Include Files ****************/
10 #include "cc_pal_types.h"
11 #include "cc_pal_trng.h"
12 #include "cc_pal_log.h"
13
14 #if (CC_CONFIG_TRNG_MODE==0)
15 #define CC_CONFIG_SAMPLE_CNT_ROSC_1 5000
16 #define CC_CONFIG_SAMPLE_CNT_ROSC_2 1000
17 #define CC_CONFIG_SAMPLE_CNT_ROSC_3 500
18 #define CC_CONFIG_SAMPLE_CNT_ROSC_4 0
19 #elif (CC_CONFIG_TRNG_MODE==1)
20 /* amount of bytes for the required entropy bits = ROUND_UP(ROUND_UP(((required entropy bits)/(entropy per bit)), 1024), (EHR width in bytes)) / 8
21 (multiple of the window size 1024 bits and multiple of the EHR width 192 bits) */
22 #define CC_CONFIG_TRNG90B_AMOUNT_OF_BYTES 144 /* ROUND_UP(ROUND_UP((384/0.5), 1024), 192) / 8 = 144 */
23
24 /*** NIST SP 800-90B (2nd Draft) 4.4.1 ***/
25 /* C = ROUND_UP(1+(-log(W)/H)), W = 2^(-40), H=(entropy per bit) */
26 #define CC_CONFIG_TRNG90B_REPETITION_COUNTER_CUTOFF 81 /* ROUND_UP(1+(40/0.5)) = 81 */
27
28 /*** NIST SP 800-90B (2nd Draft) 4.4.2 ***/
29 /* C =CRITBINOM(W, power(2,(-H)),1-a), W = 1024, a = 2^(-40), H=(entropy per bit) */
30 #define CC_CONFIG_TRNG90B_ADAPTIVE_PROPORTION_CUTOFF 823 /* =CRITBINOM(1024, power(2,(-0.5)),1-2^(-40)) */
31
32 /* sample count for each ring oscillator */
33 /* for unallowed rosc, sample count = 0 */
34 #define CC_CONFIG_SAMPLE_CNT_ROSC_1 1000
35 #define CC_CONFIG_SAMPLE_CNT_ROSC_2 1000
36 #define CC_CONFIG_SAMPLE_CNT_ROSC_3 500
37 #define CC_CONFIG_SAMPLE_CNT_ROSC_4 0
38 #else
39 #error "CC_CONFIG_TRNG_MODE not defined or not supported"
40 #endif
41
42
43 /**
44 * @brief This function return the TRNG user parameters.
45 *
46 *
47 * @return Zero on success.
48 * @return A non-zero value on failure.
49 */
CC_PalTrngParamGet(CC_PalTrngParams_t * pTrngParams,size_t * pParamsSize)50 CCError_t CC_PalTrngParamGet(CC_PalTrngParams_t *pTrngParams, /*!< [out] A pointer to the TRNG user parameters. */
51 size_t *pParamsSize) /*!< [in/out] A poiinter to size of the TRNG user parameters structure used.
52 As input: the function needs to verify its size is the same as CC_PalTrngParams_t.
53 As output: return the size of CC_PalTrngParams_t for Library size verification */
54 {
55 CCError_t error = CC_OK;
56
57 if ((pTrngParams == NULL) ||
58 (pParamsSize == NULL) ||
59 (*pParamsSize != sizeof(CC_PalTrngParams_t))){
60 return CC_FAIL;
61 }
62
63 *pParamsSize = sizeof(CC_PalTrngParams_t);
64
65 pTrngParams->SubSamplingRatio1 = CC_CONFIG_SAMPLE_CNT_ROSC_1;
66 pTrngParams->SubSamplingRatio2 = CC_CONFIG_SAMPLE_CNT_ROSC_2;
67 pTrngParams->SubSamplingRatio3 = CC_CONFIG_SAMPLE_CNT_ROSC_3;
68 pTrngParams->SubSamplingRatio4 = CC_CONFIG_SAMPLE_CNT_ROSC_4;
69
70 #if (CC_CONFIG_TRNG_MODE==1)
71 pTrngParams->trngModeParams.numOfBytes = CC_CONFIG_TRNG90B_AMOUNT_OF_BYTES;
72 pTrngParams->trngModeParams.repetitionCounterCutoff = CC_CONFIG_TRNG90B_REPETITION_COUNTER_CUTOFF;
73 pTrngParams->trngModeParams.adaptiveProportionCutOff = CC_CONFIG_TRNG90B_ADAPTIVE_PROPORTION_CUTOFF;
74
75 #endif
76 return error;
77 }
78
