Bitcoin Core  26.99.0
P2P Digital Currency
testrand_impl.h
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1 /***********************************************************************
2  * Copyright (c) 2013-2015 Pieter Wuille *
3  * Distributed under the MIT software license, see the accompanying *
4  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
5  ***********************************************************************/
6 
7 #ifndef SECP256K1_TESTRAND_IMPL_H
8 #define SECP256K1_TESTRAND_IMPL_H
9 
10 #include <stdint.h>
11 #include <stdio.h>
12 #include <string.h>
13 
14 #include "testrand.h"
15 #include "hash.h"
16 #include "util.h"
17 
18 static uint64_t secp256k1_test_state[4];
19 
20 SECP256K1_INLINE static void secp256k1_testrand_seed(const unsigned char *seed16) {
21  static const unsigned char PREFIX[19] = "secp256k1 test init";
22  unsigned char out32[32];
23  secp256k1_sha256 hash;
24  int i;
25 
26  /* Use SHA256(PREFIX || seed16) as initial state. */
28  secp256k1_sha256_write(&hash, PREFIX, sizeof(PREFIX));
29  secp256k1_sha256_write(&hash, seed16, 16);
30  secp256k1_sha256_finalize(&hash, out32);
31  for (i = 0; i < 4; ++i) {
32  uint64_t s = 0;
33  int j;
34  for (j = 0; j < 8; ++j) s = (s << 8) | out32[8*i + j];
35  secp256k1_test_state[i] = s;
36  }
37 }
38 
39 SECP256K1_INLINE static uint64_t rotl(const uint64_t x, int k) {
40  return (x << k) | (x >> (64 - k));
41 }
42 
43 SECP256K1_INLINE static uint64_t secp256k1_testrand64(void) {
44  /* Test-only Xoshiro256++ RNG. See https://prng.di.unimi.it/ */
45  const uint64_t result = rotl(secp256k1_test_state[0] + secp256k1_test_state[3], 23) + secp256k1_test_state[0];
46  const uint64_t t = secp256k1_test_state[1] << 17;
51  secp256k1_test_state[2] ^= t;
53  return result;
54 }
55 
56 SECP256K1_INLINE static uint64_t secp256k1_testrand_bits(int bits) {
57  if (bits == 0) return 0;
58  return secp256k1_testrand64() >> (64 - bits);
59 }
60 
61 SECP256K1_INLINE static uint32_t secp256k1_testrand32(void) {
62  return secp256k1_testrand64() >> 32;
63 }
64 
65 static uint32_t secp256k1_testrand_int(uint32_t range) {
66  uint32_t mask = 0;
67  uint32_t range_copy;
68  /* Reduce range by 1, changing its meaning to "maximum value". */
69  VERIFY_CHECK(range != 0);
70  range -= 1;
71  /* Count the number of bits in range. */
72  range_copy = range;
73  while (range_copy) {
74  mask = (mask << 1) | 1U;
75  range_copy >>= 1;
76  }
77  /* Generation loop. */
78  while (1) {
79  uint32_t val = secp256k1_testrand64() & mask;
80  if (val <= range) return val;
81  }
82 }
83 
84 static void secp256k1_testrand256(unsigned char *b32) {
85  int i;
86  for (i = 0; i < 4; ++i) {
87  uint64_t val = secp256k1_testrand64();
88  b32[0] = val;
89  b32[1] = val >> 8;
90  b32[2] = val >> 16;
91  b32[3] = val >> 24;
92  b32[4] = val >> 32;
93  b32[5] = val >> 40;
94  b32[6] = val >> 48;
95  b32[7] = val >> 56;
96  b32 += 8;
97  }
98 }
99 
100 static void secp256k1_testrand_bytes_test(unsigned char *bytes, size_t len) {
101  size_t bits = 0;
102  memset(bytes, 0, len);
103  while (bits < len * 8) {
104  int now;
105  uint32_t val;
106  now = 1 + (secp256k1_testrand_bits(6) * secp256k1_testrand_bits(5) + 16) / 31;
107  val = secp256k1_testrand_bits(1);
108  while (now > 0 && bits < len * 8) {
109  bytes[bits / 8] |= val << (bits % 8);
110  now--;
111  bits++;
112  }
113  }
114 }
115 
116 static void secp256k1_testrand256_test(unsigned char *b32) {
118 }
119 
120 static void secp256k1_testrand_flip(unsigned char *b, size_t len) {
121  b[secp256k1_testrand_int(len)] ^= (1 << secp256k1_testrand_bits(3));
122 }
123 
124 static void secp256k1_testrand_init(const char* hexseed) {
125  unsigned char seed16[16] = {0};
126  if (hexseed && strlen(hexseed) != 0) {
127  int pos = 0;
128  while (pos < 16 && hexseed[0] != 0 && hexseed[1] != 0) {
129  unsigned short sh;
130  if ((sscanf(hexseed, "%2hx", &sh)) == 1) {
131  seed16[pos] = sh;
132  } else {
133  break;
134  }
135  hexseed += 2;
136  pos++;
137  }
138  } else {
139  FILE *frand = fopen("/dev/urandom", "rb");
140  if ((frand == NULL) || fread(&seed16, 1, sizeof(seed16), frand) != sizeof(seed16)) {
141  uint64_t t = time(NULL) * (uint64_t)1337;
142  fprintf(stderr, "WARNING: could not read 16 bytes from /dev/urandom; falling back to insecure PRNG\n");
143  seed16[0] ^= t;
144  seed16[1] ^= t >> 8;
145  seed16[2] ^= t >> 16;
146  seed16[3] ^= t >> 24;
147  seed16[4] ^= t >> 32;
148  seed16[5] ^= t >> 40;
149  seed16[6] ^= t >> 48;
150  seed16[7] ^= t >> 56;
151  }
152  if (frand) {
153  fclose(frand);
154  }
155  }
156 
157  printf("random seed = %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n", seed16[0], seed16[1], seed16[2], seed16[3], seed16[4], seed16[5], seed16[6], seed16[7], seed16[8], seed16[9], seed16[10], seed16[11], seed16[12], seed16[13], seed16[14], seed16[15]);
158  secp256k1_testrand_seed(seed16);
159 }
160 
161 static void secp256k1_testrand_finish(void) {
162  unsigned char run32[32];
163  secp256k1_testrand256(run32);
164  printf("random run = %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n", run32[0], run32[1], run32[2], run32[3], run32[4], run32[5], run32[6], run32[7], run32[8], run32[9], run32[10], run32[11], run32[12], run32[13], run32[14], run32[15]);
165 }
166 
167 #endif /* SECP256K1_TESTRAND_IMPL_H */
FILE * fopen(const fs::path &p, const char *mode)
Definition: fs.cpp:26
void printf(const char *fmt, const Args &... args)
Format list of arguments to std::cout, according to the given format string.
Definition: tinyformat.h:1077
static void secp256k1_sha256_initialize(secp256k1_sha256 *hash)
static void secp256k1_sha256_finalize(secp256k1_sha256 *hash, unsigned char *out32)
static void secp256k1_sha256_write(secp256k1_sha256 *hash, const unsigned char *data, size_t size)
#define SECP256K1_INLINE
Definition: util.h:48
#define VERIFY_CHECK(cond)
Definition: util.h:139
static uint32_t secp256k1_testrand_int(uint32_t range)
Definition: testrand_impl.h:65
static void secp256k1_testrand_flip(unsigned char *b, size_t len)
static void secp256k1_testrand_bytes_test(unsigned char *bytes, size_t len)
static SECP256K1_INLINE uint64_t secp256k1_testrand64(void)
Definition: testrand_impl.h:43
static void secp256k1_testrand256(unsigned char *b32)
Definition: testrand_impl.h:84
static SECP256K1_INLINE void secp256k1_testrand_seed(const unsigned char *seed16)
Definition: testrand_impl.h:20
static void secp256k1_testrand_init(const char *hexseed)
static uint64_t secp256k1_test_state[4]
Definition: testrand_impl.h:18
static void secp256k1_testrand_finish(void)
static SECP256K1_INLINE uint32_t secp256k1_testrand32(void)
Definition: testrand_impl.h:61
static SECP256K1_INLINE uint64_t rotl(const uint64_t x, int k)
Definition: testrand_impl.h:39
static void secp256k1_testrand256_test(unsigned char *b32)
static SECP256K1_INLINE uint64_t secp256k1_testrand_bits(int bits)
Definition: testrand_impl.h:56