/*
 * HALFLM2.C
 * Performs Dictionary/BF cracking of bytes 8-16 of LM Response.
 * 
 * Usesful when second part of password is weak!>
 * Also if first part of response is found, then basically we can
 * skip the guess loop in this code :-)
 *
 * Uses JtR 1-.7.2-all9 engine
 * Compile: Place in John-1.7.2-all9/src and do gcc HALFLM2 common.o -lssl -o pleasefixeme
 * Run: ./pleasefixme
 * Code is in public domain (although the code sucks!)
 *
 * TODO:
 *
 *  - Somehow integrate into nethalflm patch i posted earlier 
 *    although i don't even have a faint idea here.
 *  - I posted on oxid.it forums for some alternate idea but haven't
 *    received any response.(I believe that they have better implementation/idea
 *    as cleary shown by Cain & Abel)!
 */

#include <stdio.h>
#include <string.h>

#include "misc.h"
#include "common.h"

#include <openssl/des.h>

#ifndef uchar
#define uchar unsigned char
#endif

#define FORMAT_LABEL         "nethalflm"
#define FORMAT_NAME          "HalfLM C/R DES"
#define ALGORITHM_NAME       "nethalflm"
#define BENCHMARK_COMMENT    ""
#define BENCHMARK_LENGTH     0
#define PLAINTEXT_LENGTH     7
#define BINARY_SIZE          8
#define SALT_SIZE            8
#define CIPHERTEXT_LENGTH    48
#define TOTAL_LENGTH         12 + 2 * SALT_SIZE + CIPHERTEXT_LENGTH

static char saved_plain[PLAINTEXT_LENGTH + 1];
static uchar challenge[SALT_SIZE + 1];
static uchar output[BINARY_SIZE + 1];
char *ciphertext = "CBC98FE03D24AB15";
static uchar binary[BINARY_SIZE];

static void nethalflm_get_binary()
{
  int i;

  for (i=0; i<BINARY_SIZE; i++) {
    binary[i] = (atoi16[ARCH_INDEX(ciphertext[i*2])])<<4;
    binary[i] |= (atoi16[ARCH_INDEX(ciphertext[i*2+1])]);
  }
}

/* Avoid clash with NETLM_fmt.c */
static void setup_des_key(unsigned char key_56[], des_key_schedule *ks)
{
  des_cblock key;

  key[0] = key_56[0];
  key[1] = (key_56[0] << 7) | (key_56[1] >> 1);
  key[2] = (key_56[1] << 6) | (key_56[2] >> 2);
  key[3] = (key_56[2] << 5) | (key_56[3] >> 3);
  key[4] = (key_56[3] << 4) | (key_56[4] >> 4);
  key[5] = (key_56[4] << 3) | (key_56[5] >> 5);
  key[6] = (key_56[5] << 2) | (key_56[6] >> 6);
  key[7] = (key_56[6] << 1);

  des_set_key(&key, *ks);
}

static void nethalflm_crypt_all()
{
  static unsigned char magic[] = {0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25};
  des_key_schedule ks;
  unsigned char password[7 + 1];
  unsigned char lm[7]; memset(password, 0, 7 + 1);


  /* clear buffers */
  memset(lm, 0, 7);
  memset(output, 0, 8);  

  printf("\nTarget Response: ");
  int i;
  for( i = 0; i< 7 ;i++)
	  printf("%.2x",binary[i]);

  printf(" Trying key :: %s",saved_plain);

  strncpy((char *) password, saved_plain, 7);
  /* Generate first 8-bytes of LM hash */
  setup_des_key(password, &ks);
  des_ecb_encrypt((des_cblock*)magic, (des_cblock*)lm, ks, DES_ENCRYPT);

  printf(" LM Hash: ");
  for( i = 0; i< 7 ;i++)
	  printf("%.2x",lm[i]);

  /* hack */
  for( i = 6; i > 0;  i--) {
	  lm[i] = lm[i-1];
  }

  int j;
  for( j=0;j<256;j++)
  {
	  lm[0]= j;
	  /*printf("\nLM Hash after hack: ");
	  for( i = 0; i< 7 ;i++)
		  printf("%.2x",lm[i]); */
	  /* DES-encrypt challenge using LM hash */
	  setup_des_key(lm, &ks);
	  des_ecb_encrypt((des_cblock*)challenge, (des_cblock*)output, ks, DES_ENCRYPT);
	  if( memcmp(output, binary, 8) == 0 ) {
		  printf(" :) Cracked!\n");
		  /*printf("\nLM Response: ");
		  for( i = 0; i< 24 ;i++)
	  		printf("%.2x",output[i]);
		  printf("\n"); */
		  return;
	  }
	
  }
  printf(" Not found :(");
}

static void *nethalflm_get_salt(char *salt)
{
  static unsigned char binary_salt[SALT_SIZE];
  int i;
  for (i = 0; i < SALT_SIZE; ++i) {
	  binary_salt[i] = (atoi16[ARCH_INDEX(salt[i*2])] << 4) + atoi16[ARCH_INDEX(salt[i*2+1])];
  }
  return (void*)binary_salt;
}

static void nethalflm_set_salt(void *salt)
{
  memcpy(challenge, salt, SALT_SIZE);
}

static void nethalflm_set_key(char *key)
{
  int i;
  strncpy(saved_plain, key, PLAINTEXT_LENGTH);
  
  /* Upper-case password */
  for(i=0; i<PLAINTEXT_LENGTH && saved_plain[i]!=0 ; i++)
    if ((saved_plain[i] >= 'a') && (saved_plain[i] <= 'z')) saved_plain[i] ^= 0x20;
}

static char *nethalflm_get_key(int index)
{
  return saved_plain;
}

int main( int argc, char **argv ) {
    
    common_init();
    nethalflm_get_binary();
    nethalflm_set_salt( nethalflm_get_salt("1122334455667788") );
    nethalflm_set_key("bbbbbbb");
    nethalflm_crypt_all();
    nethalflm_set_key("aaaaaaa");
    nethalflm_crypt_all();
}