t_bdRandomOctets.c (original) (raw)

`` /* Id:tbdRandomOctets.cId: t_bdRandomOctets.c Id:tb​dRandomOctets.c */

/*

• Copyright (C) 2001-26 David Ireland, D.I. Management Services Pty Limited
• https://di-mgt.com.au/contact/ https://di-mgt.com.au/bigdigits.html
• SPDX-License-Identifier: MPL-2.0
• Last updated:
• Date:2026−03−2905:11:00Date: 2026-03-29 05:11:00 Date:2026−03−2905:11:00
• Revision:2.7.0Revision: 2.7.0 Revision:2.7.0
• Author:daiAuthor: dai Author:dai */

/* Examples using the bigdRand functions: bdRandomOctets() bdRandomSeeded() bdRandomNumber() */

#include <stdio.h> #include <assert.h> #include <math.h> // For sqrt in statistics #include "bigd.h" #include "bigdRand.h"

#define TEST_LEN 24 #define TEST_N 32 #define NTESTS (TEST_N * 10)

static void pr_byteshex(const char *prefix, const unsigned char *bytes, size_t nbytes, const char *suffix) { size_t i; if (prefix) printf("%s", prefix); for (i = 0; i < nbytes; i++) { printf("%02X", bytes[i]); } if (suffix) printf("%s", suffix); }

int main(void) { unsigned char bytes[TEST_LEN]; size_t nbytes; int ntests, itest, i; BIGD a, p, N; int score[TEST_N] = { 0 }; int t; BIGD temp; int themin, themax; double mean, var, sd;

ntests = TEST_LEN;
printf("Testing bdRandomOctets...\n");
for (itest = 0; itest < ntests; itest++)
{
    //printf("Test %d...\n", itest+1);
    nbytes = TEST_LEN - itest;
    bdRandomOctets(bytes, nbytes, NULL, 0);
    pr_byteshex("", bytes, nbytes, "\n");
}

// Now test bdRandomSeeded calling internal fn bdRandomOctets
printf("Testing bdRandomSeeded with bdRandomOctets()...\n");
a = bdNew();
for (i = 0; i < 10; i++)
{
    bdRandomSeeded(a, 128, NULL, 0, bdRandomOctets);
    bdPrintHex("r=", a, "\n");
}

// And generate some primes
printf("Generating primes with bdGeneratePrime() calling bdRandomOctets()...\n");
p = bdNew();
for (i = 0; i < 4; i++)
{
    bdGeneratePrime(p, 256, 128, NULL, 0, bdRandomOctets);
    bdPrintHex("p=", p, "\n");
}

// Generate some random numbers in the range [0,N-1] where N = 32
// (and keep score of count for each value)
temp = bdNew();
N = bdNew();
bdSetShort(N, TEST_N);
bdPrintDecimal("Random numbers in the range [0,N-1] computed by bdRandomNumber(N), N=", N, ":\n");
for (i = 0; i < NTESTS; i++)
{
    bdRandomNumber(a, N);
    bdPrintDecimal("", a, " ");
    /* Convert BIGD into an int */
    t = (int)bdShortMod(temp, a, 0xFFFFFFFF);
    assert(0 <= t && t < TEST_N);
    score[t] += 1;
}
printf("\n");
printf("[Statistics] Distribution over %d tests (EV=%.1f):\n", NTESTS, (double)NTESTS / TEST_N);
mean = var = 0.0;
themin = 99999;
themax = 0;
for (i = 0; i < TEST_N; i++)
{
    int v = score[i];
    printf("%d ", v);
    if (v > themax) themax = v;
    if (v < themin) themin = v;
    mean += (double)v;
    var += v * v;
}
printf("\n");
mean /= TEST_N;
var = var / TEST_N - mean*mean;
sd = sqrt(var);
printf("mean=%.3f sd=%.3f min=%d (%.2f sd) max=%d (%+.2f sd)\n", 
    mean, sd, themin, (themin-mean)/sd, themax, (themax-mean)/sd);

return 0;

} ``