1 /*---------------------------------------------------------------------------*
2 Project: NitroSDK - CRYPTO - demos
3 File: prng.c
4
5 Copyright 2006-2008 Nintendo. All rights reserved.
6
7 These coded instructions, statements, and computer programs contain
8 proprietary information of Nintendo of America Inc. and/or Nintendo
9 Company Ltd., and are protected by Federal copyright law. They may
10 not be disclosed to third parties or copied or duplicated in any form,
11 in whole or in part, without the prior written consent of Nintendo.
12
13 $Date:: 2008-10-20#$
14 $Rev: 9005 $
15 $Author: okubata_ryoma $
16 *---------------------------------------------------------------------------*/
17 /*---------------------------------------------------------------------------*
18 Pseudorandom Number Generator
19 *---------------------------------------------------------------------------*/
20
21 #include <nitro.h>
22 #include <nitro/crypto.h>
23
24 #include "prng.h"
25
26 /*---------------------------------------------------------------------------*
27 Variable Definitions
28 *---------------------------------------------------------------------------*/
29 static u8 RandomPool[MATH_SHA1_DIGEST_SIZE];
30 static u32 RandomCount = 0;
31
32 /*---------------------------------------------------------------------------*
33 Function Definitions
34 *---------------------------------------------------------------------------*/
35
36 /*---------------------------------------------------------------------------*
37 Name: AddRandomSeed
38
39 Description: Adds a random seed to the PRNG.
40
41 Arguments: random_seed: Pointer to the random seed to be added
42 len: Length of the random seed to be added
43
44 Returns: None.
45 *---------------------------------------------------------------------------*/
AddRandomSeed(u8 * random_seed,u32 len)46 void AddRandomSeed(u8* random_seed, u32 len)
47 {
48 MATHSHA1Context context;
49 MATH_SHA1Init(&context);
50 MATH_SHA1Update(&context, RandomPool, sizeof(RandomPool));
51 MATH_SHA1Update(&context, random_seed, len);
52 MATH_SHA1GetHash(&context, RandomPool);
53 }
54
55 /*---------------------------------------------------------------------------*
56 Name: ChurnRandomPool
57
58 Description: Adds the current system status as a random seed to the PRNG.
59
60 Arguments: None.
61
62 Returns: None.
63 *---------------------------------------------------------------------------*/
ChurnRandomPool(void)64 void ChurnRandomPool(void)
65 {
66 u32 data[OS_LOW_ENTROPY_DATA_SIZE/sizeof(u32)];
67 OS_GetLowEntropyData(data);
68 AddRandomSeed((u8*)data, sizeof(data));
69 }
70
71 /*---------------------------------------------------------------------------*
72 Name: GetRandomBytes
73
74 Description: Gets a random number from the PRNG.
75
76 Arguments: Pointer to the buffer that stores the random number
77 len: Length of the random number to be obtained in bytes
78
79 Returns: None.
80 *---------------------------------------------------------------------------*/
GetRandomBytes(u8 * buffer,u32 len)81 void GetRandomBytes(u8* buffer, u32 len)
82 {
83 MATHSHA1Context context;
84 u8 tmp[MATH_SHA1_DIGEST_SIZE];
85 u32 n;
86
87 while (len > 0)
88 {
89 MATH_SHA1Init(&context);
90 MATH_SHA1Update(&context, RandomPool, sizeof(RandomPool));
91 MATH_SHA1Update(&context, &RandomCount, sizeof(RandomCount));
92 MATH_SHA1GetHash(&context, tmp);
93 RandomCount++;
94
95 n = (len < MATH_SHA1_DIGEST_SIZE) ? len : MATH_SHA1_DIGEST_SIZE;
96 MI_CpuCopy8(tmp, buffer, n);
97 buffer += n;
98 len -= n;
99 }
100 }
101
102 /*---------------------------------------------------------------------------*
103 End of file
104 *---------------------------------------------------------------------------*/
105