#include <stdio.h>
#include <stdlib.h>
// Defines for register's size
#define SIZE1 19
#define SIZE2 22
#define SIZE3 23
#define SIZE4 8
// Define clock bit
#define REG1CLOCK 8
#define REGCLOCK 10
// Define byte
#define BYTE 8
// Other defines
#define ZERO 0
#define ONE 1
#define TWO 2
// Struct that holds 3 registers:
// Register X - 18 bits (clock bit = 8)
// Register Y - 21 bits (clock bit = 10)
// Register Z - 22 bits (clock bit = 10)
// The struct also holds the Keystream Byte
(8 bits).
struct Registers{
int x[SIZE1];
int y[SIZE2];
int z[SIZE3];
int out[SIZE4];
};
// Function Prototypes
int majority(int x, int y, int z); //
Function which checks if specified register is in the majority by
comparing the clock bite.
void shift(struct Registers *regs, int
size); // Function that shifts the values in the registers
void output(int size, int counter,struct
Registers *ptr); // Function to output appropriate data. (Register
values and keystream).
int main(){
// Define the struct with pre-defined
set of data.
struct Registers registers = {
{1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1},{1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1},{1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0}};
struct Registers *registersPointer =
®isters; // Pointer to the 'registers' struct.
// First output the data, that are
initialized to the registers at the start.
output(ZERO,ZERO,registersPointer);
// Variable for for loop
int i = ZERO;
// Iterate through the byte (8 times)
for(i = 0; i < BYTE; i++){
// Store the majority value from the clock
bit in m (x[8], y[10], z[10]).
int m =
majority(registers.x[REG1CLOCK],registers.y[REGCLOCK],registers.z[REGCLOCK]);
// Compare and shift the x register only
if part of the majority.
if(registers.x[REG1CLOCK] == m){
shift(registersPointer,SIZE1);
}
// Compare and shift the y register
only if part of the majority.
if(registers.y[REGCLOCK] ==m){
shift(registersPointer,SIZE2);
}
// Compare and shift the z register
only if part of the majority.
if(registers.z[REGCLOCK] ==m){
shift(registersPointer,SIZE3);
}
// Set the keystream bit (start from
the back).
registersPointer -> out[SIZE4-i] =
registers.x[SIZE1-1] ^ registers.y[SIZE2-1] ^ registers.z[SIZE3-1];
output(SIZE4-i,ONE,registersPointer); //
Output the values including the keystream.
}
// Output the final value.
output(ZERO,TWO,registersPointer);
return 0;
}
// Function to check if the majority of
clock bit.
int majority(int x, int y, int z){
if( x == y){
return x;
}else if(y == z){
return y;
}else if(x == z){
return z;
}
return 0;
}
// Function to compare register's bit using
XOR operation and swap.
void shift(struct Registers *registers,int
registerSize){
int swap = 0;
// Check which register are we dealing
with (SIZE1 = register X, SIZE2 = register Y, SIZE3 = register Z).
// After that compare using XOR
operation the last register's bits to find out the swap bit.
if(registerSize == SIZE1){
swap = registers -> x[SIZE1 - 1] ^
registers -> x[SIZE1 - 2] ^ registers -> x[SIZE1 - 3] ^
registers -> x[SIZE1 - 6];
}else if(registerSize == SIZE2){
swap = registers -> y[SIZE2-1] ^
registers -> y[SIZE2-2];
}else if(registerSize == SIZE3){
swap = registers -> z[SIZE3-1] ^
registers -> z[SIZE3-2] ^ registers -> z[SIZE3-3] ^ registers
-> z[SIZE3-15];
}
// Iterate through the register,
// Check which register we are dealing
with,
// Check if we are at element 0, if so
then put the swap value.
// Otherwise change current element to
element-1.
for(int f = (registerSize-1); f >=
0;f--){
if(registerSize == SIZE1){
if(f == 0){
registers -> x[f] = swap;
}else{
registers -> x[f] = registers ->
x[f-1];
}
}else if(registerSize == SIZE2){
if(f == 0){
registers -> y[f] = swap;
}else{
registers -> y[f] =
registers -> y[f-1];
}
}else if(registerSize == SIZE3){
if(f == 0){
registers -> z[f] = swap;
}else{
registers -> z[f] =
registers -> z[f-1];
}
}
}
}
// Function to output the data.
void output(int outvalue, int go, struct
Registers *registers){
int b = 0;
// If the first or second time
outputing, output appropriate message.
if(go == ZERO){
printf("ORGINAL CONTENT OF X, Y and
Z.");
}
if(go == TWO){
printf("\nLAST CONTENT OF X, Y and
Z.");
}
// Output values for register X.
printf("\nValue for x: ");
for(b =0; b < SIZE1 ;b++){
printf("%d,",registers->x[b]);
}
// Output values for register Y.
printf("\nValue for y: ");
for(b = 0; b < SIZE2 ;b++){
printf("%x,",registers->y[b]);
}
// Output values for register Z.
printf("\nValue for z: ");
for(b = 0; b < SIZE3;b++){
printf("%d,",registers->z[b]);
}
// Output values for the KeyStream.
if(go != ZERO && go != TWO){
printf("\nKeystream (X ^ Y ^
Z): ");
for(int i = outvalue ; i <=
SIZE4;i++){
printf("%d,",registers->out[i]);
}
}
printf("\n");
}
Output:
codept@codeptL2-16 ~/Desktop $ gcc a5.c
codept@codeptL2-16 ~/Desktop $ ./a.out
ORGINAL CONTENT OF X, Y and Z.
Value for x:
1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,
Value for y:
1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,
Value for z:
1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,
Value for x:
0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,
Value for y:
1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,
Value for z:
1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,
Keystream (X ^ Y ^ Z): 1,
Value for x:
0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,
Value for y:
0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,
Value for z:
1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,
Keystream (X ^ Y ^ Z): 0,1,
Value for x:
0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,
Value for y:
1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,
Value for z:
1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,0,
Keystream (X ^ Y ^ Z): 0,0,1,
Value for x:
0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,
Value for y:
0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,
Value for z:
1,1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,
Keystream (X ^ Y ^ Z): 0,0,0,1,
Value for x:
0,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,
Value for y:
1,0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,
Value for z:
1,1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,0,
Keystream (X ^ Y ^ Z): 0,0,0,0,1,
Value for x:
0,0,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,
Value for y:
1,0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,
Value for z:
0,1,1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,
Keystream (X ^ Y ^ Z): 0,0,0,0,0,1,
Value for x:
0,0,0,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,
Value for y:
0,1,0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,
Value for z:
1,0,1,1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,
Keystream (X ^ Y ^ Z): 1,0,0,0,0,0,1,
Value for x:
0,0,0,0,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,
Value for y:
1,0,1,0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,
Value for z:
1,0,1,1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,
Keystream (X ^ Y ^ Z): 1,1,0,0,0,0,0,1,
LAST CONTENT OF X, Y and Z.
Value for x:
0,0,0,0,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,
Value for y:
1,0,1,0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,
Value for z:
1,0,1,1,1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,
codept@codeptL2-16 ~/Desktop $
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