mirror of https://github.com/ntop/n2n.git
Logan007
4 years ago
12 changed files with 177 additions and 18 deletions
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/* The following code offers an alterate pseudo random number generator
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namely XORSHIFT128+ to use instead of C's rand(). Its performance is |
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on par with C's rand(). |
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*/ |
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#include "random_numbers.h" |
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/* The state must be seeded in a way that it is not all zero, choose some
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arbitrary defaults (in this case: taken from splitmix64) */ |
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static struct rn_generator_state_t rn_current_state = { |
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.a = 0x9E3779B97F4A7C15, |
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.b = 0xBF58476D1CE4E5B9 }; |
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/* used for mixing the initializing seed */ |
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static uint64_t splitmix64 (struct splitmix64_state_t *state) { |
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uint64_t result = state->s; |
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state->s = result + 0x9E3779B97F4A7C15; |
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result = (result ^ (result >> 30)) * 0xBF58476D1CE4E5B9; |
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result = (result ^ (result >> 27)) * 0x94D049BB133111EB; |
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return result ^ (result >> 31); |
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} |
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int n2n_srand (uint64_t seed) { |
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struct splitmix64_state_t smstate = {seed}; |
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rn_current_state.a = 0; |
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rn_current_state.b = 0; |
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rn_current_state.a = splitmix64 (&smstate); |
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rn_current_state.b = splitmix64 (&smstate); |
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/* the following lines could be deleted as soon as it is formally prooved that
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there is no seed leading to (a == b == 0). Until then, just to be safe: */ |
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if ( (rn_current_state.a == 0) && (rn_current_state.b == 0) ) { |
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rn_current_state.a = 0x9E3779B97F4A7C15; |
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rn_current_state.b = 0xBF58476D1CE4E5B9; |
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} |
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/* stabilize in unlikely case of weak state with only a few bits set */ |
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for (uint8_t i = 0; i < 32; i++) |
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n2n_rand(); |
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return 0; |
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} |
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/* The following code of xorshift128p was taken from
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https://en.wikipedia.org/wiki/Xorshift as of July, 2019
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and thus is considered public domain. */ |
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uint64_t n2n_rand () { |
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uint64_t t = rn_current_state.a; |
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uint64_t const s = rn_current_state.b; |
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rn_current_state.a = s; |
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t ^= t << 23; |
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t ^= t >> 17; |
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t ^= s ^ (s >> 26); |
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rn_current_state.b = t; |
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return t + s; |
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} |
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/* The following code tries to gather some entropy from several sources
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for use as seed. Note, that this code does not set the random generator |
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state yet, a call to n2n_srand ( n2n_seed() ) would do. */ |
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uint64_t n2n_seed (void) { |
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uint64_t seed = 0; |
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uint64_t ret = 0; |
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#ifdef SYS_getrandom |
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syscall (SYS_getrandom, &seed, sizeof(seed), GRND_NONBLOCK); |
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ret += seed; |
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#endif |
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// __RDRND__ is set only if architecturual feature is set, e.g. compile with -march=native
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#ifdef __RDRND__ |
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_rdrand64_step ((unsigned long long*)&seed); |
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ret += seed; |
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#endif |
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// __RDSEED__ ist set only if architecturual feature is set, e.g. compile with -march=native
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#ifdef __RDSEED__ |
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_rdseed64_step((unsigned long long*)&seed); |
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ret += seed; |
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#endif |
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/* The WIN32 code is still untested and thus commented
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#ifdef WIN32 |
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HCRYPTPROV crypto_provider; |
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CryptAcquireContext (&crypto_provider, NULL, (LPCWSTR)L"Microsoft Base Cryptographic Provider v1.0", |
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PROV_RSA_FULL, CRYPT_VERIFYCONTEXT); |
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CryptGenRandom (crypto_provider, 8, &seed); |
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CryptReleaseContext (crypto_provider, 0); |
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ret += seed; |
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#endif */ |
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seed = time(NULL); /* UTC in seconds */ |
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ret += seed; |
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seed = clock() * 8996146197; /* clock() = ticks since program start */ |
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ret += seed; |
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return ret; |
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} |
@ -0,0 +1,34 @@ |
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#include <stdint.h> |
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#include <time.h> |
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#if defined (__linux__) |
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#include <sys/syscall.h> |
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#include <unistd.h> |
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#define GRND_NONBLOCK 1 |
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#endif |
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#if defined (__RDRND__) || defined (__RDSEED__) |
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#include <immintrin.h> |
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#endif |
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/* The WIN32 code is still untested and thus commented
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#if defined (WIN32) |
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#include <Wincrypt.h> |
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#endif */ |
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struct rn_generator_state_t { |
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uint64_t a, b; |
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}; |
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struct splitmix64_state_t { |
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uint64_t s; |
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}; |
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int n2n_srand (uint64_t seed); |
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uint64_t n2n_rand (); |
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uint64_t n2n_seed (); |
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