XOR based cipher program in C

cipher.c

#include <stdio.h>
#include <stdlib.h>

#define MAX_LEN 1024


int main(int argc, char const *argv[])
{
	char *plain = malloc(MAX_LEN * sizeof(int));
	char *pass = malloc(MAX_LEN * sizeof(int));
	char *pass_backup = pass;

	fgets(plain, MAX_LEN, stdin);
	fgets(pass, MAX_LEN, stdin);

	while (*plain) {
		if (!*pass) pass = pass_backup;
		printf("%c", *plain++ ^ *pass++);
	}

	return 0;
}

cipher_file.c

#include <stdio.h>
#include <stdlib.h>

#define MAX_LEN 1024


int main(int argc, char const *argv[])
{
	FILE *plain_f = fopen(argv[1], "r");
	FILE *cipher_f = fopen(argv[2], "w+");

	char *plain = malloc(MAX_LEN * sizeof(int));
	const char *pass = argv[3];

	fgets(plain, MAX_LEN, plain_f);

	while (*plain) {
		if (!*pass) pass = argv[3];
		fprintf(cipher_f, "%c", *plain++ ^ *pass++);
	}

	return 0;
}