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DES

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发布时间：2019-06-26

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/* Validation sets: * * Single-length key, single-length plaintext - * Key    : 0123 4567 89ab cdef * Plain  : 0123 4567 89ab cde7 * Cipher : c957 4425 6a5e d31d * * Double-length key, single-length plaintext - * Key    : 0123 4567 89ab cdef fedc ba98 7654 3210 * Plain  : 0123 4567 89ab cde7 * Cipher : 7f1d 0a77 826b 8aff * * Double-length key, double-length plaintext - * Key    : 0123 4567 89ab cdef fedc ba98 7654 3210 * Plain  : 0123 4567 89ab cdef 0123 4567 89ab cdff * Cipher : 27a0 8440 406a df60 278f 47cf 42d6 15d7 * * Triple-length key, single-length plaintext - * Key    : 0123 4567 89ab cdef fedc ba98 7654 3210 89ab cdef 0123 4567 * Plain  : 0123 4567 89ab cde7 * Cipher : de0b 7c06 ae5e 0ed5 * * Triple-length key, double-length plaintext - * Key    : 0123 4567 89ab cdef fedc ba98 7654 3210 89ab cdef 0123 4567 * Plain  : 0123 4567 89ab cdef 0123 4567 89ab cdff * Cipher : ad0d 1b30 ac17 cf07 0ed1 1c63 81e4 4de5 * * d3des V5.0a rwo 9208.07 18:44 Graven Imagery **********************************************************************/

/* ========================================================================== ** * *                                    DES.c * * Copyright: *  Copyright (C) 2003, 2004 by Christopher R. Hertel * * Email: crh@ubiqx.mn.org * * $Id: DES.c,v 0.7 2009/04/08 06:47:39 crh Exp $ * * -------------------------------------------------------------------------- ** * * Description: * *  Implements DES encryption, but not decryption. *  DES is used to create LM password hashes and both LM and NTLM Responses. * * -------------------------------------------------------------------------- ** * * License: * *  This library is free software; you can redistribute it and/or *  modify it under the terms of the GNU Lesser General Public *  License as published by the Free Software Foundation; either *  version 2.1 of the License, or (at your option) any later version. * *  This library is distributed in the hope that it will be useful, *  but WITHOUT ANY WARRANTY; without even the implied warranty of *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU *  Lesser General Public License for more details. * *  You should have received a copy of the GNU Lesser General Public *  License along with this library; if not, write to the Free Software *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA * * -------------------------------------------------------------------------- ** * * Notes: * *  This implementation was created by studying many existing examples *  found in Open Source, in the public domain, and in various documentation. *  The SMB protocol makes minimal use of the DES function, so this is a *  minimal implementation.  That which is not required has been removed. * *  The SMB protocol uses the DES algorithm as a hash function, not an *  encryption function.  The auth_DEShash() implemented here is a one-way *  function.  The reverse is not implemented in this module.  Also, there *  is no attempt at making this either fast or efficient.  There is no *  need, as the auth_DEShash() function is used for generating the LM *  Response from a 7-byte key and an 8-byte challenge.  It is not intended *  for use in encrypting large blocks of data or data streams. * *  As stated above, this implementation is based on studying existing work *  in the public domain or under Open Source (specifically LGPL) license. *  The code, however, is written from scratch.  Obviously, I make no claim *  with regard to those earlier works (except to claim that I am grateful *  to the previous implementors whose work I studied).  See the list of *  references below for resources I used. * *  References: *    I read through the libmcrypt code to see how they put the pieces *    together.  See: http://mcrypt.hellug.gr/ *    Libmcrypt is available under the terms of the LGPL. * *    The libmcrypt implementation includes the following credits: *      written 12 Dec 1986 by Phil Karn, KA9Q; large sections adapted *      from the 1977 public-domain program by Jim Gillogly *      Modified for additional speed - 6 December 1988 Phil Karn *      Modified for parameterized key schedules - Jan 1991 Phil Karn *      modified in order to use the libmcrypt API by Nikos Mavroyanopoulos *      All modifications are placed under the license of libmcrypt. * *    See also Phil Karn's privacy and security page: *      http://www.ka9q.net/privacy.html * *    I relied heavily upon: *      Applied Cryptography, Second Edition: *        Protocols, Algorithms, and Source Code in C *      by Bruce Schneier. ISBN 0-471-11709-9, John Wiley & Sons, Inc., 1996 *    Particularly Chapter 12. * *    Here's one more DES resource, which I found quite helpful (aside from *    the Clinton jokes): *      http://www.aci.net/kalliste/des.htm *    Has moved to: *      http://orlingrabbe.com/des.htm * *    Finally, the use of DES in SMB is covered in: *      Implementing CIFS - the Common Internet File System *      by your truly.  ISBN 0-13-047116-X, Prentice Hall PTR., August 2003 *    Section 15.3, in particular. *    (Online at: http://ubiqx.org/cifs/SMB.html#SMB.8.3) * * ========================================================================== ** */#include "DES.h"/* -------------------------------------------------------------------------- ** * Static Constants: *//* Initial permutation map. * In the first step of DES, the bits of the initial plaintext are rearranged  * according to the map given below.  This map and those like it are read by * the Permute() function (below) which uses the maps as a guide when moving * bits from one place to another. * * Note that the values here are all one less than those shown in Schneier. * That's because C likes to start counting from 0, not 1. * * According to Schneier (Ch12, pg 271), the purpose of the initial * permutation was to make it easier to load plaintext and ciphertext into * a DES ecryption chip.  I have no idea why that would be the case. */static const uint8_t InitialPermuteMap[64] =   {  57, 49, 41, 33, 25, 17,  9, 1,  59, 51, 43, 35, 27, 19, 11, 3,  61, 53, 45, 37, 29, 21, 13, 5,  63, 55, 47, 39, 31, 23, 15, 7,  56, 48, 40, 32, 24, 16,  8, 0,  58, 50, 42, 34, 26, 18, 10, 2,  60, 52, 44, 36, 28, 20, 12, 4,  62, 54, 46, 38, 30, 22, 14, 6  };/* Key permutation map. * Like the input data and encryption result, the key is permuted before * the algorithm really gets going.  The original algorithm called for an * eight-byte key in which each byte contained a parity bit.  During the * key permutiation, the parity bits were discarded.  The DES algorithm, * as used with SMB, does not make use of the parity bits.  Instead, SMB * passes 7-byte keys to DES.  For DES implementations that expect parity, * the parity bits must be added.  In this case, however, we're just going * to start with a 7-byte (56 bit) key.  KeyPermuteMap, below, is adjusted * accordingly and, of course, each entry in the map is reduced by 1 with * respect to the documented values because C likes to start counting from * 0, not 1. */static const uint8_t KeyPermuteMap[56] =   {  49, 42, 35, 28, 21, 14,  7,  0,  50, 43, 36, 29, 22, 15,  8,  1,  51, 44, 37, 30, 23, 16,  9,  2,  52, 45, 38, 31, 55, 48, 41, 34,  27, 20, 13,  6, 54, 47, 40, 33,  26, 19, 12,  5, 53, 46, 39, 32,  25, 18, 11,  4, 24, 17, 10,  3,  };/* Key rotation table. * At the start of each round of encryption, the key is split and each * 28-bit half is rotated left.  The number of bits of rotation per round * is given in the table below. */static const uint8_t KeyRotation[16] =  { 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };/* Key compression table. * This table is used to select 48 of the 56 bits of the key. * The left and right halves of the source text are each 32 bits, * but they are expanded to 48 bits and the results are XOR'd * against the compressed (48-bit) key. */static const uint8_t KeyCompression[48] =  {  13, 16, 10, 23,  0,  4,  2, 27,  14,  5, 20,  9, 22, 18, 11,  3,  25,  7, 15,  6, 26, 19, 12,  1,  40, 51, 30, 36, 46, 54, 29, 39,  50, 44, 32, 47, 43, 48, 38, 55,  33, 52, 45, 41, 49, 35, 28, 31  };/* Data expansion table. * This table is used after the data block (64-bits) has been split * into two 32-bit (4-byte) halves (generally denoted L and R). * Each 32-bit half is "expanded", using this table, to a 48 bit * data block, which is then XOR'd with the 48 bit subkey for the * round. */static const uint8_t DataExpansion[48] =  {  31,  0,  1,  2,  3,  4,  3,  4,   5,  6,  7,  8,  7,  8,  9, 10,  11, 12, 11, 12, 13, 14, 15, 16,  15, 16, 17, 18, 19, 20, 19, 20,  21, 22, 23, 24, 23, 24, 25, 26,  27, 28, 27, 28, 29, 30, 31,  0  };/* The (in)famous S-boxes. * These are used to perform substitutions. * Six bits worth of input will return four bits of output. * The four bit values are stored in these tables.  Each table has * 64 entries...and 6 bits provides a number between 0 and 63. * There are eight S-boxes, one per 6 bits of a 48-bit value. * Thus, 48 bits are reduced to 32 bits.  Obviously, this step * follows the DataExpansion step. * * Note that the literature generally shows this as 8 arrays each * with four rows and 16 colums.  There is a complex formula for * mapping the 6 bit input values to the correct row and column. * I've pre-computed that mapping, and the tables below provide * direct 6-bit input to 4-bit output.  See pp 274-274 in Schneier. */static const uint8_t SBox[8][64] =  {    {  /* S0 */    14,  0,  4, 15, 13,  7,  1,  4,  2, 14, 15,  2, 11, 13,  8,  1,     3, 10, 10,  6,  6, 12, 12, 11,  5,  9,  9,  5,  0,  3,  7,  8,     4, 15,  1, 12, 14,  8,  8,  2, 13,  4,  6,  9,  2,  1, 11,  7,    15,  5, 12, 11,  9,  3,  7, 14,  3, 10, 10,  0,  5,  6,  0, 13    },    {  /* S1 */    15,  3,  1, 13,  8,  4, 14,  7,  6, 15, 11,  2,  3,  8,  4, 14,     9, 12,  7,  0,  2,  1, 13, 10, 12,  6,  0,  9,  5, 11, 10,  5,     0, 13, 14,  8,  7, 10, 11,  1, 10,  3,  4, 15, 13,  4,  1,  2,     5, 11,  8,  6, 12,  7,  6, 12,  9,  0,  3,  5,  2, 14, 15,  9    },    {  /* S2 */    10, 13,  0,  7,  9,  0, 14,  9,  6,  3,  3,  4, 15,  6,  5, 10,     1,  2, 13,  8, 12,  5,  7, 14, 11, 12,  4, 11,  2, 15,  8,  1,    13,  1,  6, 10,  4, 13,  9,  0,  8,  6, 15,  9,  3,  8,  0,  7,    11,  4,  1, 15,  2, 14, 12,  3,  5, 11, 10,  5, 14,  2,  7, 12    },    {  /* S3 */     7, 13, 13,  8, 14, 11,  3,  5,  0,  6,  6, 15,  9,  0, 10,  3,     1,  4,  2,  7,  8,  2,  5, 12, 11,  1, 12, 10,  4, 14, 15,  9,    10,  3,  6, 15,  9,  0,  0,  6, 12, 10, 11,  1,  7, 13, 13,  8,    15,  9,  1,  4,  3,  5, 14, 11,  5, 12,  2,  7,  8,  2,  4, 14    },    {  /* S4 */     2, 14, 12, 11,  4,  2,  1, 12,  7,  4, 10,  7, 11, 13,  6,  1,     8,  5,  5,  0,  3, 15, 15, 10, 13,  3,  0,  9, 14,  8,  9,  6,     4, 11,  2,  8,  1, 12, 11,  7, 10,  1, 13, 14,  7,  2,  8, 13,    15,  6,  9, 15, 12,  0,  5,  9,  6, 10,  3,  4,  0,  5, 14,  3    },    {  /* S5 */    12, 10,  1, 15, 10,  4, 15,  2,  9,  7,  2, 12,  6,  9,  8,  5,     0,  6, 13,  1,  3, 13,  4, 14, 14,  0,  7, 11,  5,  3, 11,  8,     9,  4, 14,  3, 15,  2,  5, 12,  2,  9,  8,  5, 12, 15,  3, 10,     7, 11,  0, 14,  4,  1, 10,  7,  1,  6, 13,  0, 11,  8,  6, 13    },    {  /* S6 */     4, 13, 11,  0,  2, 11, 14,  7, 15,  4,  0,  9,  8,  1, 13, 10,     3, 14, 12,  3,  9,  5,  7, 12,  5,  2, 10, 15,  6,  8,  1,  6,     1,  6,  4, 11, 11, 13, 13,  8, 12,  1,  3,  4,  7, 10, 14,  7,    10,  9, 15,  5,  6,  0,  8, 15,  0, 14,  5,  2,  9,  3,  2, 12    },    {  /* S7 */    13,  1,  2, 15,  8, 13,  4,  8,  6, 10, 15,  3, 11,  7,  1,  4,    10, 12,  9,  5,  3,  6, 14, 11,  5,  0,  0, 14, 12,  9,  7,  2,     7,  2, 11,  1,  4, 14,  1,  7,  9,  4, 12, 10, 14,  8,  2, 13,     0, 15,  6, 12, 10,  9, 13,  0, 15,  3,  3,  5,  5,  6,  8, 11    }  };/* P-Box permutation. * This permutation is applied to the result of the S-Box Substitutions. * It's a straight-forward re-arrangement of the bits. */static const uint8_t PBox[32] =  {  15,  6, 19, 20, 28, 11, 27, 16,   0, 14, 22, 25,  4, 17, 30,  9,   1,  7, 23, 13, 31, 26,  2,  8,  18, 12, 29,  5, 21, 10,  3, 24  };/* Final permutation map. * This is supposed to be the inverse of the Initial Permutation, * but there's been a bit of fiddling done. * As always, the values given are one less than those in the literature * (because C starts counting from 0, not 1).  In addition, the penultimate * step in DES is to swap the left and right hand sides of the ciphertext. * The inverse of the Initial Permutation is then applied to produce the * final result. * To save a step, the map below does the left/right swap as well as the * inverse permutation. */static const uint8_t FinalPermuteMap[64] =  {   7, 39, 15, 47, 23, 55, 31, 63,   6, 38, 14, 46, 22, 54, 30, 62,   5, 37, 13, 45, 21, 53, 29, 61,   4, 36, 12, 44, 20, 52, 28, 60,   3, 35, 11, 43, 19, 51, 27, 59,   2, 34, 10, 42, 18, 50, 26, 58,   1, 33,  9, 41, 17, 49, 25, 57,   0, 32,  8, 40, 16, 48, 24, 56  };/* -------------------------------------------------------------------------- ** * Macros: * *  CLRBIT( STR, IDX ) *    Input:  STR - (uchar *) pointer to an array of 8-bit bytes. *            IDX - (int) bitwise index of a bit within the STR array *                  that is to be cleared (that is, given a value of 0). *    Notes:  This macro clears a bit within an array of bits (which is *            built within an array of bytes). *          - The macro converts to an assignment of the form A &= B. *          - The string of bytes is viewed as an array of bits, read from *            highest order bit first.  The highest order bit of a byte *            would, therefore, be bit 0 (within that byte). * *  SETBIT( STR, IDX ) *    Input:  STR - (uchar *) pointer to an array of 8-bit bytes. *            IDX - (int) bitwise index of a bit within the STR array *                  that is to be set (that is, given a value of 1). *    Notes:  This macro sets a bit within an array of bits (which is *            built within an array of bytes). *          - The macro converts to an assignment of the form A |= B. *          - The string of bytes is viewed as an array of bits, read from *            highest order bit first.  The highest order bit of a byte *            would, therefore, be bit 0 (within that byte). * *  GETBIT( STR, IDX ) *    Input:  STR - (uchar *) pointer to an array of 8-bit bytes. *            IDX - (int) bit-wise index of a bit within the STR array *                  that is to be read. *    Output: True (1) if the indexed bit was set, else false (0). * * -------------------------------------------------------------------------- ** */#define CLRBIT( STR, IDX ) ( (STR)[(IDX)/8] &= ~(0x01 << (7 - ((IDX)%8))) )#define SETBIT( STR, IDX ) ( (STR)[(IDX)/8] |= (0x01 << (7 - ((IDX)%8))) )#define GETBIT( STR, IDX ) (( ((STR)[(IDX)/8]) >> (7 - ((IDX)%8)) ) & 0x01)/* -------------------------------------------------------------------------- ** * Static Functions: */static void Permute( uchar   *dst,               const uchar   *src,               const uint8_t *map,               const int      mapsize )  /* ------------------------------------------------------------------------ **   * Performs a DES permutation, which re-arranges the bits in an array of   * bytes.   *   *  Input:  dst     - Destination into which to put the re-arranged bits.   *          src     - Source from which to read the bits.   *          map     - Permutation map.   *          mapsize - Number of bytes represented by the .  This also   *                    represents the number of bytes to be copied to 
      
       .   *   *  Output: none.   *   *  Notes:  
       
         and 
        
          must not point to the same location.   *   *        - No checks are done to ensure that there is enough room   *          in 
         
          , or that the bit numbers in 
           do not exceed * the bits available in 
           
            . A good reason to make this * function static (private). * * - The 
            
              value is in bytes. All permutations in DES * use tables that are a multiple of 8 bits, so there is no * need to handle partial bytes. (Yes, I know that there * are some machines out there that still use bytes of a size * other than 8 bits. For our purposes we'll stick with 8-bit * bytes.) * * ------------------------------------------------------------------------ ** */ { int bitcount; int i; /* Clear all bits in the destination. */ for( i = 0; i < mapsize; i++ ) dst[i] = 0; /* Set destination bit if the mapped source bit it set. */ bitcount = mapsize * 8; for( i = 0; i < bitcount; i++ ) { if( GETBIT( src, map[i] ) ) SETBIT( dst, i ); } } /* Permute */static void KeyShift( uchar *key, const int numbits ) /* ------------------------------------------------------------------------ ** * Split the 56-bit key in half & left rotate each half by 
             
               bits. * * Input: key - The 56-bit key to be split-rotated. * numbits - The number of bits by which to rotate the key. * * Output: none. * * Notes: There are probably several better ways to implement this. * * ------------------------------------------------------------------------ ** */ { int i; uchar keep = key[0]; /* Copy the highest order bits of the key. */ /* Repeat the shift process 
              
                times. */ for( i = 0; i < numbits; i++ ) { int j; /* Shift the entire thing, byte by byte. */ for( j = 0; j < 7; j++ ) { if( j && (key[j] & 0x80) ) /* If the top bit of this byte is set. */ key[j-1] |= 0x01; /* ...shift it to last byte's low bit. */ key[j] <<= 1; /* Then left-shift the whole byte. */ } /* Now move the high-order bits of each 28-bit half-key to their * correct locations. * Bit 27 is the lowest order bit of the first half-key. * Before the shift, it was the highest order bit of the 2nd half-key. */ if( GETBIT( key, 27 ) ) /* If bit 27 is set... */ { CLRBIT( key, 27 ); /* ...clear bit 27. */ SETBIT( key, 55 ); /* ...set lowest order bit of 2nd half-key. */ } /* We kept the highest order bit of the first half-key in 
               
                . * If it's set, copy it to bit 27. */ if( keep & 0x80 ) SETBIT( key, 27 ); /* Rotate the 
                
                  byte too, in case 
                 
                   is 2 and there's * a second round coming. */ keep <<= 1; } } /* KeyShift */static void sbox( uchar *dst, const uchar *src ) /* ------------------------------------------------------------------------ ** * Perform S-Box substitutions. * * Input: dst - Destination byte array into which the S-Box substituted * bitmap will be written. * src - Source byte array. * * Output: none. * * Notes: It's really not possible (for me, anyway) to understand how * this works without reading one or more detailed explanations. * Quick overview, though: * * After the DataExpansion step (in which a 32-bit bit array is * expanded to a 48-bit bit array) the expanded data block is * XOR'd with 48-bits worth of key. That 48 bits then needs to * be condensed back into 32 bits. * * The S-Box substitution handles the data reduction by breaking * the 48-bit value into eight 6-bit values. For each of these * 6-bit values there is a table (an S-Box table). The table * contains 64 possible values. Conveniently, a 6-bit integer * can represent a value between 0 and 63. * * So, if you think of the 48-bit bit array as an array of 6-bit * integers, you use S-Box table 0 with the 0th 6-bit value. * Table 1 is used with the 6-bit value #1, and so on until #7. * Within each table, the correct substitution is found based * simply on the value of the 6-bit integer. * * Well, the original algorithm (and most documentation) don't * make it so simple. There's a complex formula for mapping * the 6-bit values to the correct substitution. Fortunately, * those lookups can be precomputed (and have been for this * implementation). See pp 274-274 in Schneier. * * Oh, and the substitute values are all 4-bit values, so each * 6-bits gets reduced to 4-bits resulting in a 32-bit bit array. * * ------------------------------------------------------------------------ ** */ { int i; /* Clear the destination array. */ for( i = 0; i < 4; i++ ) dst[i] = 0; /* For each set of six input bits... */ for( i = 0; i < 8; i++ ) { int j; int Snum; int bitnum; /* Extract the 6-bit integer from the source. * This will be the lookup key within the SBox[i] array. */ for( Snum = j = 0, bitnum = (i * 6); j < 6; j++, bitnum++ ) { Snum <<= 1; Snum |= GETBIT( src, bitnum ); } /* Find the correct value in the correct SBox[] * and copy it into the destination. * Left shift the nibble four bytes for even values of 
                  . */ if( 0 == (i%2) ) dst[i/2] |= ((SBox[i][Snum]) << 4); else dst[i/2] |= SBox[i][Snum]; } } /* sbox */static void xor( uchar *dst, const uchar *a, const uchar *b, const int count ) /* ------------------------------------------------------------------------ ** * Perform an XOR operation on two byte arrays. * * Input: dst - Destination array to which the result will be written. * a - The first string of bytes. * b - The second string of bytes. * count - Number of bytes to XOR against one another. * * Output: none. * * Notes: This function operates on whole byte chunks. There's no need * to XOR partial bytes so no need to write code to handle it. * * - This function essentially implements dst = a ^ b; for byte * arrays. * * - 
                   
                     may safely point to the same location as 
                     or . * * ------------------------------------------------------------------------ ** */ { int i; for( i = 0; i < count; i++ ) dst[i] = a[i] ^ b[i]; } /* xor *//* -------------------------------------------------------------------------- ** * Functions: */uchar *auth_DESkey8to7( uchar *dst, const uchar *key ) /* ------------------------------------------------------------------------ ** * Compress an 8-byte DES key to its 7-byte form. * * Input: dst - Pointer to a memory location (minimum 7 bytes) to accept * the compressed key. * key - Pointer to an 8-byte DES key. See the notes below. * * Output: A pointer to the compressed key (same as 
                      
                       ) or NULL if * either 
                       
                         or 
                        
                          were NULL. * * Notes: There are no checks done to ensure that 
                         
                           and 
                          
                            point * to sufficient space. Please be carefull. * * The two pointers, 
                           
                             and 
                            
                              may point to the same * memory location. Internally, a temporary buffer is used and * the results are copied back to 
                             
                              . * * The DES algorithm uses 8 byte keys by definition. The first * step in the algorithm, however, involves removing every eigth * bit to produce a 56-bit key (seven bytes). SMB authentication * skips this step and uses 7-byte keys. The 
                              
                                * algorithm in this module expects 7-byte keys. This function * is used to convert an 8-byte DES key into a 7-byte SMB DES key. * * ------------------------------------------------------------------------ ** */ { int i; uchar tmp[7]; static const uint8_t map8to7[56] = { 0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62 }; if( (NULL == dst) || (NULL == key) ) return( NULL ); Permute( tmp, key, map8to7, 7 ); for( i = 0; i < 7; i++ ) dst[i] = tmp[i]; return( dst ); } /* auth_DESkey8to7 */uchar *auth_DEShash( uchar *dst, const uchar *key, const uchar *src ) /* ------------------------------------------------------------------------ ** * DES encryption of the input data using the input key. * * Input: dst - Destination buffer. It *must* be at least eight bytes * in length, to receive the encrypted result. * key - Encryption key. Exactly seven bytes will be used. * If your key is shorter, ensure that you pad it to seven * bytes. * src - Source data to be encrypted. Exactly eight bytes will * be used. If your source data is shorter, ensure that * you pad it to eight bytes. * * Output: A pointer to the encrpyted data (same as 
                               
                                ). * * Notes: In SMB, the DES function is used as a hashing function rather * than an encryption/decryption tool. When used for generating * the LM hash the 
                                
                                  input is the known value "KGS!@#$%" and * the key is derived from the password entered by the user. * When used to generate the LM or NTLM response, the 
                                 
                                   is * derived from the LM or NTLM hash, and the challenge is used * as the 
                                  
                                    input. * See: http://ubiqx.org/cifs/SMB.html#SMB.8.3 * * - This function is called "DEShash" rather than just "DES" * because it is only used for creating LM hashes and the * LM/NTLM responses. For all practical purposes, however, it * is a full DES encryption implementation. * * - This DES implementation does not need to be fast, nor is a * DES decryption function needed. The goal is to keep the * code small, simple, and well documented. * * - The input values are copied and refiddled within the module * and the result is not written to 
                                   
                                     until the very last * step, so it's okay if 
                                    
                                      points to the same memory as * 
                                     
                                       or 
                                      
                                       . * * ------------------------------------------------------------------------ ** */ { int i; /* Loop counter. */ uchar K[7]; /* Holds the key, as we manipulate it. */ uchar D[8]; /* The data block, as we manipulate it. */ /* Create the permutations of the key and the source. */ Permute( K, key, KeyPermuteMap, 7 ); Permute( D, src, InitialPermuteMap, 8 ); /* DES encryption proceeds in 16 rounds. * The stuff inside the loop is known in the literature as "function f". */ for( i = 0; i < 16; i++ ) { int j; uchar *L = D; /* The left 4 bytes (half) of the data block. */ uchar *R = &(D[4]); /* The right half of the ciphertext block. */ uchar Rexp[6]; /* Expanded right half. */ uchar Rn[4]; /* New value of R, as we manipulate it. */ uchar SubK[6]; /* The 48-bit subkey. */ /* Generate the subkey for this round. */ KeyShift( K, KeyRotation[i] ); Permute( SubK, K, KeyCompression, 6 ); /* Expand the right half (R) of the data block to 48 bytes, * then XOR the result with the Subkey for this round. */ Permute( Rexp, R, DataExpansion, 6 ); xor( Rexp, Rexp, SubK, 6 ); /* S-Box substitutions, P-Box permutation, and final XOR. * The S-Box substitutions return a 32-bit value, which is then * run through the 32-bit to 32-bit P-Box permutation. The P-Box * result is then XOR'd with the left-hand half of the key. * (Rexp is used as a temporary variable between the P-Box & XOR). */ sbox( Rn, Rexp ); Permute( Rexp, Rn, PBox, 4 ); xor( Rn, L, Rexp, 4 ); /* The previous R becomes the new L, * and Rn is moved into R ready for the next round. */ for( j = 0; j < 4; j++ ) { L[j] = R[j]; R[j] = Rn[j]; } } /* The encryption is complete. * Now reverse-permute the ciphertext to produce the final result. * We actually combine two steps here. The penultimate step is to * swap the positions of L and R in the result of the 16 rounds, * after which the reverse of the Initial Permutation is applied. * To save a step, the FinalPermuteMap applies both the L/R swap * and the inverse of the Initial Permutation. */ Permute( dst, D, FinalPermuteMap, 8 ); return( dst ); } /* auth_DEShash *//* ========================================================================== */