RC4 2nd Byte Bias Demo, Multithreaded

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <stdlib.h>
#include <pthread.h>
#include <sys/time.h>

#define KEY_LENGTH            16
#define ITERATIONS            16777216
#define THREAD_COUNT          4
#define ITERATIONS_PER_THREAD ITERATIONS/THREAD_COUNT

void ksa(int state[], int key[]) {
    int i,j=0,t;
    for (i=0; i<256; ++i)
        state[i] = i;
    for (i=0; i<256; ++i) {
        j = (j + state[i] + key[i % KEY_LENGTH]) % 256;
        t = state[i];
        state[i] = state[j];
        state[j] = t;
    }
}

void prga(int state[], int out[]) {
    int i=0,j=0,x,t;
    for (x=0; x<256; ++x) {
        i = (i+1) % 256;
        j = (j+state[i]) % 256;
        t = state[i];
        state[i] = state[j];
        state[j] = t;
        out[x] = state[(state[i] + state[j]) % 256];
    }
}

void makeRandomKey(int key[]) {
    int i;
    for (i=0; i<KEY_LENGTH; ++i)
        key[i] = rand() % 256;
}

void populateOccurances(int* occurances) {
    int state[256];
    int out[256];
    int key[KEY_LENGTH];
    int i,j;
    srand(time(NULL));
    for (i=0; i<ITERATIONS_PER_THREAD; ++i) {
        makeRandomKey(key);
        ksa(state, key);
        prga(state, out);
        for (j=0; j<256; ++j)
            ++occurances[j*256+out[j]];
    }
}

static void *populateOccurancesThread(void *p) {
    int* occurances = (int*) p;
    populateOccurances(occurances);
    pthread_exit(NULL);
}

int main(int argc, char *argv[]) {

    struct timeval time_started, time_now, time_diff;
    gettimeofday(&time_started, NULL);

    int occurances[THREAD_COUNT][256*256];
    int bytePosition,charOccurance;
    int i,k;
    pthread_t threads[THREAD_COUNT];

    for (k=0; k<THREAD_COUNT; ++k)
        for (i=0; i<256*256; ++i)
            occurances[k][i] = 0;

    for (k=0; k<THREAD_COUNT; ++k) {
        int rc = pthread_create(&threads[k], NULL, populateOccurancesThread, (void*)&occurances[k]);
        if (rc) {
            printf("ERROR; return code from pthread_create() is %d\n", rc);
            exit(-1);
        }
    }

    for (k=0; k<THREAD_COUNT; ++k) {
        void * status;
        int rc = pthread_join(threads[k], &status);
        if (rc) {
            printf("ERROR: return code from pthread_join() is %d\n", rc);
            exit(-1);
        }
    }

    for (bytePosition=0; bytePosition<256; ++bytePosition) {
        printf("%d,", bytePosition);
    }

    printf("\n");
    for (charOccurance=0; charOccurance<256; ++charOccurance) {
        for (bytePosition=0; bytePosition<256; ++bytePosition) {
            int occuranceSum = 0;
            for (k=0; k<THREAD_COUNT; ++k) {
                occuranceSum += occurances[k][charOccurance*256+bytePosition];
            }
            printf("%d,", occuranceSum);
        }
        printf("\n");
    }

    gettimeofday(&time_now, NULL);
    timersub(&time_now, &time_started, &time_diff);
    printf("Time taken,%ld.%.6ld s\n", time_diff.tv_sec, time_diff.tv_usec);

    return 0;
}