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

int main()
{
        char key[20] = { 0x87, 0xff, 0x63, 0xa3, 0x8d, 0x75, 0xd8, 0xc4, 0x1a, 0x84, 0xca, 0x24, 0x5b, 0x66, 0x0c, 0x1f, 0xc6, 0xe2, 0xcc, 0xea };

        FILE *fileptr;
        char *buffer;
        long filelen;

        fileptr = fopen("flag.enc", "rb");
        fseek(fileptr, 0, SEEK_END);
        filelen = ftell(fileptr);
        rewind(fileptr);

        buffer = (char *)malloc((filelen+1)*sizeof(char));
        fread(buffer, filelen, 1, fileptr);
        fclose(fileptr);

        int i;
        for(i = 0; i < filelen; i++) {
                if( i != 0 && i % 20 == 0 )
                        printf("\n");
                printf("%c", buffer[i] ^ key[i%20]);
        }

        return 0;
}