#include <stdio.h>
#define SYMBOLS 8
#define KEYLENGTH 3
#define MSGLENGTH 4

int main(void){

void swap(int*, int*);
int stream[SYMBOLS];
int key[KEYLENGTH];
int message[MSGLENGTH];
int crypto[MSGLENGTH];

int finalkey[MSGLENGTH];
for (int i = 0; i < MSGLENGTH; ++i)
{
	printf("enter message digit number %d\n", i);
	scanf("%d", &message[i]);
}
for(int i = 0; i < SYMBOLS; i++){
		stream[i] = i;
		if(i < KEYLENGTH){
			printf("enter key digit number %d\n", i);
			scanf("%d", &key[i]);
		}
	}

	printf("KEY = ");
	for(int i = 0; i < KEYLENGTH; i++){
		printf("|%d", key[i] );
	}


printf("\n\n KSA PHASE \n\n");

int j = 0;
int index = 0;
	for(int i = 0; i < SYMBOLS; i++){
		printf("\nIterazione %d\n", i);
		printf("j = %d \n", j );
		index = i % KEYLENGTH;
		printf("index = %d \n", index);
		j = (j + stream[i] + key[index]) % SYMBOLS;
		printf("stream[%d] = %d \n", i, index);
		printf("key[index]) = %d \n", key[ i % KEYLENGTH]);
		printf("(j + stream[i] + key[index]) mod %d = %d \n", SYMBOLS, j);
		swap(&stream[i],&stream[j]);
		for(int k = 0 ; k < SYMBOLS ; k++){
			printf("|%d ", stream[k]);
		}
	}

	printf("\n\nFINAL STREAM = ");
	for(int i = 0; i < SYMBOLS; i++){
		printf("|%d ", stream[i]);
	}

printf("\n\n PRGA PHASE \n\n");
j= 0;
int k = 0;
int h = 0;
int i = 0;
	for(int i = 0; i < MSGLENGTH; i++){
		finalkey[i] = 0;
		crypto[i] = 0;
}
while( h < MSGLENGTH)	{
	i = (i + 1) % SYMBOLS;
	printf("i = %d\n", i);
		j = (j + stream[i]) % SYMBOLS;
		printf("j = %d\n", j);

		swap(&stream[i], &stream[j]);
		int k = (stream[i] + stream[j]) % SYMBOLS;

		printf("k = %d\n", k);
		finalkey[h] = stream[k];
		printf("key[%d] = %d\n", k, stream[k]);
		h++;
}

		printf("\n\n");

	printf("FINAL KEY = ");

	for(i = 0; i < MSGLENGTH; i++){
		printf("|%d", finalkey[i]);
	}

	printf("\n\n ENCRYPTION PHASE \n\n");
	for(i = 0; i < MSGLENGTH; i++){
		crypto[i] = message[i] ^ finalkey[i];
		printf("%d = %d xor %d\n", crypto[i], message[i], finalkey[i]);
	}

	printf("\nFINAL MESSAGE = ");

	for(i = 0; i < MSGLENGTH; i++){
		printf("|%d", crypto[i]);
	}

}


void swap(int* a, int* b){
	int temp;
	temp = *a;
	*a = *b;
	*b = temp;

}