Depending on the data 755 may also be unsafe. I'm guessing that whatever data is being written must be both private and correct. If you were I then I'd set the minimum possible permissions and ensure that the process doing the writing was either the directory and file owner or at least in the right group. I'd hate for you to write down credit cards or something using that scheme. In general consider this advice incomplete and a guess at best. If you don't already understand unix permissions then you'll have to learn them prior to completing whatever you're doing. Of course there's additional security to be had by using public-key cryptography. Again, you have to know what you're doing to use it sanely (like not putting the private key on the server among others).
printf "You are here %08x\n", unpack "L!", unpack "P4", pack "L!", B::