Simple XOR encryption

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

int main(int argc, char** argv)
{
    if (argc != 3)
    {
        printf("Usage: %s file key\n", argv[0]);
        return -1;
    }

    FILE *fp = fopen(argv[1], "r");


    if (fp == NULL)
    {
        printf("Could not open %s\n", argv[1]);
        return -1;
    }


    int keyLen = strlen(argv[2]);
    char c;
    for (int n = 0; (c = fgetc(fp)) != EOF; n++, n %= keyLen)
    {
        printf("%c", c ^ argv[2][n]);
    }

    return 0;
}