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

void encrypt(char* msg, size_t msg_size, char* key, size_t key_size)
{
    size_t key_index = 0;
    for (size_t i = 0; i < msg_size; i++)
    {
        msg[i] ^= key[key_index];

        ++key_index;
        if (key_index > key_size)
            key_index = 0;
    }
}

void encrypt_file(char* in_name, char* out_name, char* key, size_t key_size)
{
    char buf[1024];
    size_t nread;

    FILE* in_file = fopen(in_name, "rb");
    FILE* out_file = fopen(out_name, "wb");

    int count = 0;
    while ((nread = fread(buf, 1, sizeof(buf), in_file)) > 0)
    {
        count += nread;
        printf("Bytes read: %i\nTotal: %i\n\n", nread, count);
        encrypt(buf, nread, key, key_size);
        fwrite(buf, 1, nread, out_file);
    }

    if (ferror(in_file) || ferror(out_file))
    {
        printf("Some error occured lol.\n");
    }

    fclose(in_file);
    fclose(out_file);
}

int main()
{
    char key[] = "KsAdda2223132dfSDASDSSDASDWDsfsad3A";
    size_t key_size = strlen(key);

    encrypt_file("lifesaver2.jpg", "encrypted.jpg", key, key_size);
    return 0;
}