461 lines
14 KiB
C
461 lines
14 KiB
C
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/**************************************************************************
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* Unix-like crypt(3) Algorithm for Password Encryption
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*
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* File : crypt3.c
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* Purpose : Provides crypt(3) functionality to ANSI C compilers
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* without a need for the crypt library.
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* Author : Michael Dipperstein
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* Date : November 3, 1998
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*
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***************************************************************************
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* The source in this file is heavily borrowed from the crypt3.c file
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* found on several ftp sites on the Internet. The original source
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* claimed to be BSD, but was not distributed with any BSD license or
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* copyright claims. I am releasing the source that I have provided into
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* public domain without any restrictions, warranties, or copyright
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* claims of my own.
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*
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* The code below has been cleaned and compiles correctly under, gcc,
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* lcc, and Borland's bcc C compilers. A bug involving the left and
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* right halves of the encrypted data block in the widely published
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* crypt3.c source has been fixed by this version. All implicit register
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* declarations have been removed, because they generated suboptimal code.
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* All constant data has been explicitly declared as const and all
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* declarations have been given a minimal scope, because I'm paranoid.
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*
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* Caution: crypt() returns a pointer to static data. I left it this way
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* to maintain backward compatibility. The downside is that
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* successive calls will cause previous results to be lost.
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* This can easily be changed with only minor modifications to
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* the function crypt().
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**************************************************************************/
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/* Initial permutation */
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static const char IP[] =
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{
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58, 50, 42, 34, 26, 18, 10, 2,
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60, 52, 44, 36, 28, 20, 12, 4,
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62, 54, 46, 38, 30, 22, 14, 6,
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64, 56, 48, 40, 32, 24, 16, 8,
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57, 49, 41, 33, 25, 17, 9, 1,
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59, 51, 43, 35, 27, 19, 11, 3,
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61, 53, 45, 37, 29, 21, 13, 5,
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63, 55, 47, 39, 31, 23, 15, 7,
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};
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/* Final permutation, FP = IP^(-1) */
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static const char FP[] = {
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40, 8, 48, 16, 56, 24, 64, 32,
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39, 7, 47, 15, 55, 23, 63, 31,
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38, 6, 46, 14, 54, 22, 62, 30,
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37, 5, 45, 13, 53, 21, 61, 29,
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36, 4, 44, 12, 52, 20, 60, 28,
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35, 3, 43, 11, 51, 19, 59, 27,
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34, 2, 42, 10, 50, 18, 58, 26,
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33, 1, 41, 9, 49, 17, 57, 25,
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};
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/**************************************************************************
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* Permuted-choice 1 from the key bits to yield C and D.
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* Note that bits 8,16... are left out:
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* They are intended for a parity check.
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**************************************************************************/
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static const char PC1_C[] =
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{
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57, 49, 41, 33, 25, 17, 9,
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1, 58, 50, 42, 34, 26, 18,
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10, 2, 59, 51, 43, 35, 27,
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19, 11, 3, 60, 52, 44, 36,
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};
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static const char PC1_D[] =
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{
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63, 55, 47, 39, 31, 23, 15,
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7, 62, 54, 46, 38, 30, 22,
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14, 6, 61, 53, 45, 37, 29,
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21, 13, 5, 28, 20, 12, 4,
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};
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/* Sequence of shifts used for the key schedule. */
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static const char shifts[] =
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{1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};
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/**************************************************************************
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* Permuted-choice 2, to pick out the bits from the CD array that generate
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* the key schedule.
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**************************************************************************/
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static const char PC2_C[] =
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{
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14, 17, 11, 24, 1, 5,
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3, 28, 15, 6, 21, 10,
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23, 19, 12, 4, 26, 8,
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16, 7, 27, 20, 13, 2,
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};
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static const char PC2_D[] =
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{
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41, 52, 31, 37, 47, 55,
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30, 40, 51, 45, 33, 48,
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44, 49, 39, 56, 34, 53,
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46, 42, 50, 36, 29, 32,
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};
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/* The C and D arrays used to calculate the key schedule. */
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static char C[28];
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static char D[28];
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/* The key schedule. Generated from the key. */
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static char KS[16][48];
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/* The E bit-selection table. */
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static char E[48];
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static const char e2[] =
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{
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32, 1, 2, 3, 4, 5,
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4, 5, 6, 7, 8, 9,
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8, 9, 10, 11, 12, 13,
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12, 13, 14, 15, 16, 17,
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16, 17, 18, 19, 20, 21,
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20, 21, 22, 23, 24, 25,
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24, 25, 26, 27, 28, 29,
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28, 29, 30, 31, 32, 1,
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};
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/**************************************************************************
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* Function: setkey
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*
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* Description: Set up the key schedule from the encryption key.
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*
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* Inputs: char *key
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* pointer to 64 character array. Each character represents a
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* bit in the key.
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*
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* Returns: none
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**************************************************************************/
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void setkey(char *key)
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{
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int i, j, k, temp;
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/**********************************************************************
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* First, generate C and D by permuting the key. The low order bit of
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* each 8-bit char is not used, so C and D are only 28 bits apiece.
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**********************************************************************/
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for(i = 0; i < 28; i++)
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{
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C[i] = key[PC1_C[i] - 1];
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D[i] = key[PC1_D[i] - 1];
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}
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/**********************************************************************
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* To generate Ki, rotate C and D according to schedule and pick up a
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* permutation using PC2.
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**********************************************************************/
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for(i = 0; i < 16; i++)
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{
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/* rotate */
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for(k = 0; k < shifts[i]; k++)
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{
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temp = C[0];
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for(j = 0; j < 28 - 1; j++)
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C[j] = C[j+1];
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C[27] = temp;
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temp = D[0];
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for(j = 0; j < 28 - 1; j++)
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D[j] = D[j+1];
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D[27] = temp;
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}
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/* get Ki. Note C and D are concatenated */
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for(j = 0; j < 24; j++)
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{
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KS[i][j] = C[PC2_C[j] - 1];
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KS[i][j + 24] = D[PC2_D[j] - 28 -1];
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}
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}
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/* load E with the initial E bit selections */
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for(i=0; i < 48; i++)
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E[i] = e2[i];
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}
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/**************************************************************************
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* The 8 selection functions. For some reason, they give a 0-origin
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* index, unlike everything else.
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**************************************************************************/
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static const char S[8][64] =
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{
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{
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14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
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0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
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4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
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15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13
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},
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{
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15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
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3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
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0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
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13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9
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},
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{
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10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
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13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
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13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
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1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12
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},
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{
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7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
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13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
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10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
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3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14
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},
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{
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2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
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14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
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4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
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11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3
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},
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{
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12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
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10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
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9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
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4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13
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},
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{
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4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
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13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
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1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
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6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12
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},
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{
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13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
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1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
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7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
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2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11
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}
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};
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/**************************************************************************
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* P is a permutation on the selected combination of the current L and key.
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**************************************************************************/
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static const char P[] =
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{
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16, 7, 20, 21,
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29, 12, 28, 17,
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1, 15, 23, 26,
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5, 18, 31, 10,
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2, 8, 24, 14,
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32, 27, 3, 9,
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19, 13, 30, 6,
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22, 11, 4, 25,
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};
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/* The combination of the key and the input, before selection. */
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static char preS[48];
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/**************************************************************************
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* Function: encrypt
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*
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* Description: Uses DES to encrypt a 64 bit block of data. Requires
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* setkey to be invoked with the encryption key before it may
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* be used. The results of the encryption are stored in block.
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*
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* Inputs: char *block
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* pointer to 64 character array. Each character represents a
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* bit in the data block.
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*
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* Returns: none
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**************************************************************************/
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void encrypt(char *block)
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{
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int i, ii, temp, j, k;
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char left[32], right[32]; /* block in two halves */
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char old[32];
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char f[32];
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/* First, permute the bits in the input */
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for(j = 0; j < 32; j++)
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left[j] = block[IP[j] - 1];
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for(;j < 64; j++)
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right[j - 32] = block[IP[j] - 1];
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/* Perform an encryption operation 16 times. */
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for(ii= 0; ii < 16; ii++)
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{
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i = ii;
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/* Save the right array, which will be the new left. */
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for(j = 0; j < 32; j++)
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old[j] = right[j];
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/******************************************************************
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* Expand right to 48 bits using the E selector and
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* exclusive-or with the current key bits.
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******************************************************************/
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for(j =0 ; j < 48; j++)
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preS[j] = right[E[j] - 1] ^ KS[i][j];
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/******************************************************************
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* The pre-select bits are now considered in 8 groups of 6 bits ea.
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* The 8 selection functions map these 6-bit quantities into 4-bit
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* quantities and the results are permuted to make an f(R, K).
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* The indexing into the selection functions is peculiar;
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* it could be simplified by rewriting the tables.
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******************************************************************/
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for(j = 0; j < 8; j++)
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{
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temp = 6 * j;
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k = S[j][(preS[temp + 0] << 5) +
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(preS[temp + 1] << 3) +
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(preS[temp + 2] << 2) +
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(preS[temp + 3] << 1) +
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(preS[temp + 4] << 0) +
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(preS[temp + 5] << 4)];
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temp = 4 * j;
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f[temp + 0] = (k >> 3) & 01;
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f[temp + 1] = (k >> 2) & 01;
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f[temp + 2] = (k >> 1) & 01;
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f[temp + 3] = (k >> 0) & 01;
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}
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/******************************************************************
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* The new right is left ^ f(R, K).
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* The f here has to be permuted first, though.
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******************************************************************/
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for(j = 0; j < 32; j++)
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right[j] = left[j] ^ f[P[j] - 1];
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/* Finally, the new left (the original right) is copied back. */
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for(j = 0; j < 32; j++)
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left[j] = old[j];
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}
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/* The output left and right are reversed. */
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for(j = 0; j < 32; j++)
|
||
|
|
{
|
||
|
|
temp = left[j];
|
||
|
|
left[j] = right[j];
|
||
|
|
right[j] = temp;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* The final output gets the inverse permutation of the very original. */
|
||
|
|
for(j = 0; j < 64; j++)
|
||
|
|
{
|
||
|
|
i = FP[j];
|
||
|
|
if (i < 33)
|
||
|
|
block[j] = left[FP[j] - 1];
|
||
|
|
else
|
||
|
|
block[j] = right[FP[j] - 33];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**************************************************************************
|
||
|
|
* Function: crypt
|
||
|
|
*
|
||
|
|
* Description: Clone of Unix crypt(3) function.
|
||
|
|
*
|
||
|
|
* Inputs: char *pw
|
||
|
|
* pointer to 8 character encryption key (user password)
|
||
|
|
* char *salt
|
||
|
|
* pointer to 2 character salt used to modify the DES results.
|
||
|
|
*
|
||
|
|
* Returns: Pointer to static array containing the salt concatenated
|
||
|
|
* on to the encrypted results. Same as stored in passwd file.
|
||
|
|
**************************************************************************/
|
||
|
|
char *crypt(char *pw, char *salt)
|
||
|
|
{
|
||
|
|
int i, j, temp;
|
||
|
|
char c,
|
||
|
|
block[66]; /* 1st store key, then results */
|
||
|
|
static char iobuf[16]; /* encrypted results */
|
||
|
|
|
||
|
|
for(i = 0; i < 66; i++)
|
||
|
|
block[i] = 0;
|
||
|
|
|
||
|
|
/* break pw into 64 bits */
|
||
|
|
for(i = 0, c = *pw; c && (i < 64); i++)
|
||
|
|
{
|
||
|
|
for(j = 0; j < 7; j++, i++)
|
||
|
|
block[i] = (c >> (6 - j)) & 01;
|
||
|
|
pw++;
|
||
|
|
c = *pw;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* set key based on pw */
|
||
|
|
setkey(block);
|
||
|
|
|
||
|
|
for(i = 0; i < 66; i++)
|
||
|
|
block[i] = 0;
|
||
|
|
|
||
|
|
for(i = 0; i < 2; i++)
|
||
|
|
{
|
||
|
|
/* store salt at beginning of results */
|
||
|
|
c = *salt++;
|
||
|
|
iobuf[i] = c;
|
||
|
|
|
||
|
|
if(c > 'Z')
|
||
|
|
c -= 6;
|
||
|
|
|
||
|
|
if(c > '9')
|
||
|
|
c -= 7;
|
||
|
|
|
||
|
|
c -= '.';
|
||
|
|
|
||
|
|
/* use salt to effect the E-bit selection */
|
||
|
|
for(j = 0; j < 6; j++)
|
||
|
|
{
|
||
|
|
if((c >> j) & 01)
|
||
|
|
{
|
||
|
|
temp = E[6 * i + j];
|
||
|
|
E[6 * i +j] = E[6 * i + j + 24];
|
||
|
|
E[6 * i + j + 24] = temp;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* call DES encryption 25 times using pw as key and initial data = 0 */
|
||
|
|
for(i = 0; i < 25; i++)
|
||
|
|
encrypt(block);
|
||
|
|
|
||
|
|
/* format encrypted block for standard crypt(3) output */
|
||
|
|
for(i=0; i < 11; i++)
|
||
|
|
{
|
||
|
|
c = 0;
|
||
|
|
for(j = 0; j < 6; j++)
|
||
|
|
{
|
||
|
|
c <<= 1;
|
||
|
|
c |= block[6 * i + j];
|
||
|
|
}
|
||
|
|
|
||
|
|
c += '.';
|
||
|
|
if(c > '9')
|
||
|
|
c += 7;
|
||
|
|
|
||
|
|
if(c > 'Z')
|
||
|
|
c += 6;
|
||
|
|
|
||
|
|
iobuf[i + 2] = c;
|
||
|
|
}
|
||
|
|
|
||
|
|
iobuf[i + 2] = '\0';
|
||
|
|
|
||
|
|
/* prevent premature NULL terminator */
|
||
|
|
if(iobuf[1] == '\0')
|
||
|
|
iobuf[1] = iobuf[0];
|
||
|
|
|
||
|
|
return(iobuf);
|
||
|
|
}
|