Renaming the file with adition of .filename Eg ".algosig" is not efficient I found it visible after pressing CTRL+H. Aren't there other ways which makes it invisible even after pressing CTRL + H. Total Hiding
Well, what you are trying to do sounds a lot like steganography, which is a rather advanced version of the technique of labelling a tape of secret files with something inconspicuous such as "Gov promo 1989".
In other words, the trick is to masquerade the information as noise in a different file, which won't easily get noticed unless you know it's hidden in there.
There are various tools for that, and you might want to have a look at this: https://superuser.com/questions/95877/steganography-software
Then there is this trick, mainly interesting because it relies on the often forgotten fact that headers are not to be assumed to always tell the truth: http://www.unixmen.com/steganography-in-ubuntu-hide-your-files-inside-an-image/
That said, I'm not sure if it's a great idea if your objective is a degree of actual security.
I would discourage even considering it unless you know very very well what you are doing.
Storing the information on a removable drive and physically locking it into a safe might be a step up − or a giant step down if, for example, your host machines somehow caches and indexes files on removable drivers.
All in all the best advice I feel like giving you, if you are aiming for security (as opposed to fun/experimentation) is: forget it.
Not sure what your end goal is.
If its security your after you need to look in to Unix file permissions or maybe even file encryption.
Hiding a file provides no measure of security.
Well you could make the containing directory owned by somebody else (eg root) and disable others' read permissions on it:
$ sudo mkdir --mode 700 lockbox $ ls lockbox/ ls: cannot open directory lockbox/: Permission denied
But you'll have to be root to enter it. With that in mind, you would do as well to just use
/root. Anybody with
sudo access can view the directory but it's probably better than nothing.
No, there is no such thing as Completely Hidden files. The point of hidden files are to hide from the user all the "ugly" system files.
If there was no way of seeing it, there would be no point, surely?