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#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include "b64.h"
#include "slowequals.h"
#include "libscrypt.h"
#ifdef _WIN32
/* On windows, strtok uses a thread-local static variable in strtok to
* make strtok thread-safe. It also neglects to provide a strtok_r. */
#define strtok_r(str, val, saveptr) strtok((str), (val))
#endif
/* pow() works with doubles. Sounds like it should cast to int correctly,
* but doesn't always. This is faster anyway
*/
static uint16_t ipow(uint16_t base, uint32_t exp)
{
uint16_t result = 1;
while (exp != 0)
{
if ((exp & 1) != 0)
result *= base;
exp >>= 1;
base *= base;
}
return result;
}
int libscrypt_check(char *mcf, const char *password)
{
/* Return values:
* <0 error
* == 0 password incorrect
* >0 correct password
*/
#ifndef _WIN32
char *saveptr = NULL;
#endif
uint32_t params;
uint64_t N;
uint8_t r, p;
int retval;
uint8_t hashbuf[64];
char outbuf[128];
uint8_t salt[32];
char *tok;
if(memcmp(mcf, SCRYPT_MCF_ID, 3) != 0)
{
/* Only version 0 supported */
return -1;
}
tok = strtok_r(mcf, "$", &saveptr);
if ( !tok )
return -1;
tok = strtok_r(NULL, "$", &saveptr);
if ( !tok )
return -1;
params = (uint32_t)strtoul(tok, NULL, 16);
if ( params == 0 )
return -1;
tok = strtok_r(NULL, "$", &saveptr);
if ( !tok )
return -1;
p = params & 0xff;
r = (params >> 8) & 0xff;
N = params >> 16;
if (N > SCRYPT_SAFE_N)
return -1;
N = ipow(2, N);
/* Useful debugging:
printf("We've obtained salt 'N' r p of '%s' %d %d %d\n", tok, N,r,p);
*/
memset(salt, 0, sizeof(salt)); /* Keeps splint happy */
retval = libscrypt_b64_decode(tok, (unsigned char*)salt, sizeof(salt));
if (retval < 1)
return -1;
retval = libscrypt_scrypt((uint8_t*)password, strlen(password), salt,
(uint32_t)retval, N, r, p, hashbuf, sizeof(hashbuf));
if (retval != 0)
return retval;
retval = libscrypt_b64_encode((unsigned char*)hashbuf, sizeof(hashbuf),
outbuf, sizeof(outbuf));
if (retval == 0)
return -1;
tok = strtok_r(NULL, "$", &saveptr);
if ( !tok )
return -1;
if(slow_equals(tok, outbuf) == 0)
{
return 0;
}
return 1; /* This is the "else" condition */
}
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