NIS SDES Implementation

#include
#include

typedef unsigned short int uint16 ;
typedef unsigned char uchar;

#define BIT( b, n ) ( ( b >> n ) & 0x01 )

uint16 p10( uint16 );
uint16 p8( uint16 );
uint16 p4( uint16 ) ;
uint16 ip( uint16 );
uint16 ip_inv( uint16 );
uint16 ep( uint16 );
uint16 swap( uint16 );
void print( uint16 );
void genkeys( uint16, uint16*, uint16* );
uint16 encrypt( uint16, uint16, uint16) ;



uint16 S0[4][4] =
{
{ 1, 0, 3, 2 },
{ 3, 2, 1, 0 },
{ 0, 2, 1, 3 },
{ 3, 1, 0, 3 }
};
uint16 S1[4][4] =
{
{ 0, 1, 2, 3 },
{ 2, 0, 1, 3 },
{ 3, 0, 1, 0 },
{ 2, 1, 0, 3 }
};


void dispCorrectUsage()
{
printf( "Incorrect Usage!\n" ) ;
printf( "Correct Usage is: [

]\n" ) ;
printf( "Options:\n\t-e : Encrypt input file\n\t-d: Decrypt Input file\n" ) ;
printf( "If output file is missing, the output is redirected to the standard output\n" ) ;
return;
}

int main ( int argc, char * argv[] )
{
uint16 input,output;
uint16 key,key1,key2;
uint16 tmp;
FILE * ifp;
FILE * ofp;
uchar ch;

key = 0x097;
genkeys( key, &key1, &key2 );

if ( ( argc < 2 ) || ( argc > 4 ) )
{
dispCorrectUsage();
exit( EXIT_FAILURE ) ;
}

ifp = fopen( argv[2], "r+b" ) ;
if ( NULL == ifp )
{
printf( "Unable to open Input file!\n" ) ;
exit( EXIT_FAILURE ) ;
}

if ( 4 == argc )
{
ofp = fopen( argv[3], "w+b" );
if ( NULL == ofp )
{
printf( "Unable to open Output file!\n" ) ;
exit( EXIT_FAILURE ) ;
}
}
else
{
ofp = stdout;
}

genkeys( key, &key1, &key2 );

if ( '-' == argv[1][0] )
{
if ( 'e' == argv[1][1] )
{
while ( 0 != ( fread( &ch, sizeof( uchar ), 1, ifp ) ) )
{
input = ( uint16 ) ch;
output = encrypt( input, key1, key2 ) ;
ch = ( uchar ) output;
fwrite( &ch, sizeof( uchar ), 1, ofp ) ;
}
}
else if ( 'd' == argv[1][1] )
{
while ( 0 != ( fread( &ch, sizeof( uchar ), 1, ifp ) ) )
{
input = ( uint16 ) ch;
output = encrypt( input, key2, key1 ) ;
ch = ( uchar ) output;
fwrite( &ch, sizeof( uchar ), 1, ofp ) ;
}

}
}

return 0;
}

//9876543210 -> 7583609124
uint16 p10 ( uint16 num )
{
uint16 temp = 0x00 ;

temp |= BIT( num, 7 ) << 9;
temp |= BIT( num, 5 ) << 8;
temp |= BIT( num, 8 ) << 7;
temp |= BIT( num, 3 ) << 6;
temp |= BIT( num, 6 ) << 5;
temp |= BIT( num, 0 ) << 4;
temp |= BIT( num, 9 ) << 3;
temp |= BIT( num, 1 ) << 2;
temp |= BIT( num, 2 ) << 1;
temp |= BIT( num, 4 );

return temp ;
}

//9876543210 -> 47362501
uint16 p8( uint16 num )
{
uint16 temp = 0x00 ;

temp |= BIT( num, 4 ) << 7;
temp |= BIT( num, 7 ) << 6;
temp |= BIT( num, 3 ) << 5;
temp |= BIT( num, 6 ) << 4;
temp |= BIT( num, 2 ) << 3;
temp |= BIT( num, 5 ) << 2;
temp |= BIT( num, 0 ) << 1;
temp |= BIT( num, 1 );

return temp;
}

//3210 -> 2013
uint16 p4( uint16 num )
{
uint16 temp = 0x00;

temp |= BIT( num, 2 ) << 3;
temp |= BIT( num, 0 ) << 2;
temp |= BIT( num, 1 ) << 1;
temp |= BIT( num, 3 ) ;

return temp;
}

//76543210 -> 62574031
uint16 ip( uint16 num )
{
uint16 temp = 0x00;

temp |= BIT( num, 6 ) << 7;
temp |= BIT( num, 2 ) << 6;
temp |= BIT( num, 5 ) << 5;
temp |= BIT( num, 7 ) << 4;
temp |= BIT( num, 4 ) << 3;
temp |= BIT( num, 0 ) << 2;
temp |= BIT( num, 3 ) << 1;
temp |= BIT( num, 1 );

return temp;
}


//76543210 -> 47531602
uint16 ip_inv( uint16 num )
{
uint16 temp = 0x00;

temp |= BIT( num, 4 ) << 7;
temp |= BIT( num, 7 ) << 6;
temp |= BIT( num, 5 ) << 5;
temp |= BIT( num, 3 ) << 4;
temp |= BIT( num, 1 ) << 3;
temp |= BIT( num, 6 ) << 2;
temp |= BIT( num, 0 ) << 1;
temp |= BIT( num, 2 );

return temp;
}


//3210 -> 03212103
uint16 ep( uint16 num )
{
uint16 temp = 0x00;

temp |= BIT( num, 0 ) << 7;
temp |= BIT( num, 3 ) << 6;
temp |= BIT( num, 2 ) << 5;
temp |= BIT( num, 1 ) << 4;
temp |= BIT( num, 2 ) << 3;
temp |= BIT( num, 1 ) << 2;
temp |= BIT( num, 0 ) << 1;
temp |= BIT( num, 3 );

return temp;
}

//76543210 -> 32107654
uint16 swap( uint16 num )
{
uint16 temp = 0x00;

temp |= BIT( num, 3 ) << 7;
temp |= BIT( num, 2 ) << 6;
temp |= BIT( num, 1 ) << 5;
temp |= BIT( num, 0 ) << 4;
temp |= BIT( num, 7 ) << 3;
temp |= BIT( num, 6 ) << 2;
temp |= BIT( num, 5 ) << 1;
temp |= BIT( num, 4 );

return temp;
}

// rotate x left y bits, total size is 5 bits
#define ROT_L5(x,y) ((( (x) << (y) ) | ( (x) >> (5-y) )) & 0x1F )
// get the right 5 bits of x
#define RIGHT5(x) ( (x) & 0x1F )
// get the left 5 bits of x
#define LEFT5(x) ( ( (x) >> 5 ) & 0x1F )
// get the right 4 bits of x
#define RIGHT4(x) ( (x) & 0x0F )
// get the left 4 bits of x
#define LEFT4(x) ( ( (x) >> 4 ) & 0x0F )



void print( uint16 num )
{
int i;

for ( i = 9; i >= 0; i-- )
{
printf( "%u", BIT( num, i ) ) ;
}

return;
}

// Generating the two keys
void genkeys( uint16 key, uint16* key1, uint16* key2 )
{
uint16 k1, k2;
uint16 temp;
uint16 left, right;

temp = p10( key ) ;
left = LEFT5( temp ) ;
right = RIGHT5( temp ) ;

left = ROT_L5( left, 1 );
right = ROT_L5( right, 1 );
temp = ( left << 5 ) | right ;
k1 = p8( temp ) ;

left = ROT_L5( left, 2 ) ;
right = ROT_L5( right, 2 ) ;
temp = ( left << 5 ) | right ;
k2 = p8( temp ) ;

*key1 = k1;
*key2 = k2;
return;
}

uint16 F( uint16 input, uint16 key )
{
uint16 answer= 0x00;
uint16 temp;
uint16 left;
uint16 right;
uint16 row, col;

temp = ep( input ) ;
temp = temp ^ key;
left = LEFT4( temp );
right = RIGHT4( temp );

row = ( BIT(left, 3 ) << 1 ) | BIT(left, 0 );
col = ( BIT(left, 2 ) << 1 ) | BIT(left, 1 );
answer = S0[row][col] << 2;

row = ( BIT(right, 3 ) << 1 ) | BIT(right, 0 );
col = ( BIT(right, 2 ) << 1 ) | BIT(right, 1 );
answer |= S1[row][col];

answer = p4( answer ) ;

return answer;
}


// fk(L,R,SK) = ( L ^ F(R,SK),R )
uint16 f_k( uint16 input, uint16 key )
{
uint16 answer;
uint16 left, right;
uint16 temp;

left = LEFT4( input ) ;
right = RIGHT4( input );
temp = left ^ F( right, key );
answer = ( temp << 4 ) | right ;

return answer;
}


uint16 encrypt( uint16 input, uint16 key1, uint16 key2 )
{
uint16 answer;
uint16 temp;

temp = ip( input ) ;
temp = f_k( temp, key1 ) ;
temp = swap( temp ) ;
temp = f_k( temp, key2 ) ;
answer = ip_inv( temp ) ;

return answer;
}


//OUTPUT:

C:\TC\BIN>sdes -e ip.txt op.txt

C:\TC\BIN>sdes -d op.txt
Hello World

ip.txt:-
Hello World

op.txt:-
SĺºgEég«º”