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#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <float.h>
#include <stdint.h>
#include <math.h>
#ifndef S_SPLINT_S /* Including this here triggers a known bug in splint */
#include <unistd.h>
#endif
#include "libscrypt.h"
/* ilog2 for powers of two */
static uint32_t scrypt_ilog2(uint32_t n)
{
#ifndef S_SPLINT_S
/* Check for a valid power of two */
if (n < 2 || (n & (n - 1)))
return -1;
#endif
uint32_t t = 1;
while (((uint32_t)1 << t) < n)
{
if(t > SCRYPT_SAFE_N)
return (uint32_t) -1; /* Check for insanity */
t++;
}
return t;
}
#ifdef _MSC_VER
#define SNPRINTF _snprintf
#else
#define SNPRINTF snprintf
#endif
int libscrypt_mcf(uint32_t N, uint32_t r, uint32_t p, const char *salt,
const char *hash, char *mcf)
{
uint32_t t, params;
int s;
if(!mcf || !hash)
return 0;
/* Although larger values of r, p are valid in scrypt, this mcf format
* limits to 8 bits. If your number is larger, current computers will
* struggle
*/
if(r > (uint8_t)(-1) || p > (uint8_t)(-1))
return 0;
t = scrypt_ilog2(N);
if (t < 1)
return 0;
params = (r << 8) + p;
params += (uint32_t)t << 16;
/* Using snprintf - not checking for overflows. We've already
* determined that mcf should be defined as at least SCRYPT_MCF_LEN
* in length
*/
s = SNPRINTF(mcf, SCRYPT_MCF_LEN, SCRYPT_MCF_ID "$%06x$%s$%s", (unsigned int)params, salt, hash);
if (s > SCRYPT_MCF_LEN)
return 0;
return 1;
}
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