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