#include <stdio.h>

#include <string.h>

#include "erldp.h"

#include <nettle/md5.h>

#include <nettle/base16.h>

static uint64_t next_random(uint64_t x);

void create_cookie(uint64_t seed, char *cookie, size_t size) {

uint64_t x;

int i;

x = seed;

for (i = size-1; i >= 0; i--) {

x = next_random(x);

cookie[i] = 'A' + ((26*x) / 0x1000000000);

}

}

static uint64_t next_random(uint64_t x) {

uint64_t ret;

ret = (x * 17059465ULL + 1) & 0xfffffffff;

return ret;

}

void compute_response(size_t cookie_size, const char *cookie,

uint32_t challenge, uint8_t *digest) {

struct md5_ctx ctx;

char challenge_s[256];

memset(challenge_s, 0, sizeof(challenge_s));

snprintf(challenge_s, sizeof(challenge_s)-1, "%u", challenge);

md5_init(&ctx);

md5_update(&ctx, cookie_size, (uint8_t *) cookie);

md5_update(&ctx, strlen(challenge_s), (uint8_t *) challenge_s);

md5_digest(&ctx, 16, digest);

}