226

What processes and systems are in place so that Google is not able to copy the data on my computer? None. Google Chrome usually runs with the permissions of your user account. The application can then read and modify local files to the same extent your user account can. (These permissions apply to most of the programs you're using.) So you need to trust ...


103

No, that's impossible, unless you change the definition of a file. A file is arbitrary data. Arbitrary data can be encrypted data. Even if we only allow structured data, structured data can - if we assume no space constraints - be abused to store all arbitrary data* (citation needed). Which brings us to the starting point. You can have partial success, ...


95

Read-only file systems can by definition not be written to (At least not digitally. What you do with a hole puncher and a neodymium magnet is your own business). Examples: Live CDs, from which you can boot into an operating system which will look the same on every boot. WORM (Write Once Read Many) devices, used for example by financial institutions which ...


85

A piece of unsandboxed software running on a PC/Mac has (generally) the same privileges as the user running it and therefore can access any data that can be accessed by the user. You are trusting Google (and any other software vendor whose code you execute) not to do anything malicious with that access. If you don't trust Google, your only option as a ...


80

There's an even easier way to bypass the "execute" permission: copy the program into a directory you own and set the "execute" bit. The "execute" permission isn't a security measure. Security is provided at a lower level, with the operating system restricting specific actions. This is done because, on many Unix-like systems (especially in the days of ...


74

If decryption only relies on the keyfile and this keyfile is readily available, there is indeed no significant security benefit in your setup. What you can do though is store the keyfile on a removable device (e.g. a USB stick) and detach it when you are not around. That way decryption is only possible when you are present and the removable device is ...


45

No, NTFS is not encrypted by default. can data be read straight from the sectors in clear text? Yes, by default NTFS files are unencrypted. Since NTFS 3.0, EFS (Encrypting File System) is a feature of NTFS, but By default, no files are encrypted, but encryption can be enabled by users on a per-file, per-directory, or per-drive basis.


45

Yes, most likely. However there can always be edge cases: SSDs are doing wear leveling etc., and will most probably not write your zeroes to the same cells your original data was written to. How the attacker will find and access that data is another matter altogether of course. On a traditional spinning HDD, the original data may exist on other sectors ...


38

If you are running a Linux distribution with SELinux, it is possible to have an additional layer of security. SELinux is an OS-level technology which allows tight restrictions on what processes — like your browser process — can access. In fact, in Fedora and in Red Hat Enterprise Linux (disclaimer: I work for Red Hat, on Fedora!), there is a light ...


35

I think you will want more of a philosophical answer than a technical one, given what you are rejecting. A file is just a discrete collection of bits. Relevance and meaning are overlaid onto those bits by a human, but ultimately, it's just bits. How would it be possible to determine if the bits you have are in the same sequence in some unknown previous ...


29

File extensions The file extension actually has absolutely nothing to do with the data in the file or how that data is structured. Windows likes to make you think the extension is somehow magical - it's not, it's just part of the file name, and tells Windows which program to launch when you open the file. (Linux/Android and MacOS/iOS still use file ...


27

You can set the execute bit, but not the read bit, on an executable file. That way, noone will be able to copy the file, but people can execute it anyway. This is quite pointless today, because a) it works for compiled programs only, not with scripts (on most systems); b) these days, with 90% of all unixes being linux, people can copy executables from just ...


27

Loads of file systems don't have native file system level encryption support. Software-encrypted files can be stored on any file system though, just like any other file. The file system cannot tell the difference between random data and encrypted data. Is there a way to permanently disable any sort of encryption at the OS level? Not so long as code can ...


24

First of all (just to be on the safe side) verify the file isn't in the Recycle Bin. If it is, choose Restore and of course shred the recovered file (or maybe you can shred it while inside the Recycle Bin). If the file has been "truly deleted", recover it using an undelete tool such as Piriform's Recuva, then shred it for good. Note (suggested by Chris H): ...


24

1 should not present any danger as long as the file is just saved somewhere and no attempts to open it with anything are made. If you view it even with a text editor, there's already a small danger of exploits. In the case of 2 there are vulnerabilities and exploits, so there are dangers. Some examples of such possible scenarios: Arbitrary file writes ...


23

Lawyers. You have a contract with Google stating what they will do / you allow them to do. This is called the Google Chrome Terms of Service . And obviously, you have carefully read it before installing it. This includes¹ excerpts like this (emphasis by me): By default, usage statistics and crash reports are sent to Google (…). Usage statistics contain ...


21

Imagine you're on a desert island and I hand you a print out of the US constitution, claiming that it is an exact copy (no words changed). With nothing to compare it against, you have no way to verify that, right? As @schroeder says, a digital file (and its metadata) is just a collection of bits. How do you determine if the bits you have in front of you are ...


18

What processes and systems are in place so that Google is not able to copy the data on my computer? There's not anything in place that makes it so they can't but there's something in place that makes it unlikely that they would: trust. Google's product is you. They want to know everything about you and be able to predict every single decision that you will ...


18

The Connection is secure badge is in respect to the information transmitted via the network / internet. As you correctly observed, the file:// protocol uses no network connection, neither a mechanism to secure the same (because there is none), hence the badge absent. Note that the browser does not label the file:// protocol as insecure. The browser simply ...


17

So the question is: If you overwrite a file's data with, let's say, just using WriteFile Win API to overwrite all data with zeros, will that become unrecoverable? Don't use the WIN API WriteFile to try and securely delete. Instead use a secure delete tool like SysInternals sdelete. If you just use WriteFile the operating system/file system has the option ...


14

The problem with deleting files is that the file data is just one small part of what really gets saved onto your disk. On a modern filesystem there will be lots of metadata and other artifacts scattered around the disk: Journal entries on journaling filesystems, e.g. NTFS, ext3, ext4. Search index entries. Prefetch / superfetch cache entries. Shadow copies. ...


13

It actually doesn't need any forensics effort and is routinely done by Windows sysadmins. Change the password of the Windows admin by booting a toolset of choice or simply attach the disk to a Windows machine that you control Take ownership of the files in question (if needed) Profit. OR: Mount the NTFS partition under Linux, BSD or MacOS. No file ...


13

One way to dispose of a file in a 100% reliable manner is to keep it on a separate HDD partition you can purge, or, better yet, on a separate medium you can afford to destroy. If that's not practical, a good compromise is to make sure the file is only stored encrypted. When you need to "destroy" it, all you have to do is to forget the key. You don't have to ...


12

The right way to "wipe out" data is to use encryption: never let unencrypted data ever hit the disk. If you do that, then destroying the decryption key is sufficient to destroy the data. The decryption key is small and in many case you can keep it in RAM only (e.g. you type it upon boot, as a "password", which really means "a key that a human remembers"); if ...


12

There seems to be a misconception between encryption and file systems. The two are independent, one can do encryption without having a file system, and one can have a file system without doing encryption. For instance, traditional FAT16/FAT32 file systems do not "support" native encryption like NTFS does with it's EFS sub component. That doesn't mean ...


12

Effectively, yes, overwriting the blocks used by a file will make it unrecoverable. This can be done using sdelete on Windows, or shred on Linux.


12

While Demento's answer is fine, I'd also present another user case I'm personally using: I have full disk encryption set up — using LUKS on a Linux-based box, and the scheme is implemented as follows: The boot partition is encrypted and requires a password to be entered so the boot manager (GRUB) is able to mount it. The partition contains the kernel image ...


11

If you use sdelete from Microsoft (http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx) you don't have to install anything. It has an option to fill the unused disk space with zeroes too. If you already deleted the files this is what I'd just to make sure that nothing remains of the original file.


11

dir /R shows them in a command-line environment. Microsoft Windows [Version 6.1.7600] Copyright (c) 2009 Microsoft Corporation. All rights reserved. C:\Windows\system32>dir /? Displays a list of files and subdirectories in a directory. DIR [drive:][path][filename] [/A[[:]attributes]] [/B] [/C] [/D] [/L] [/N] [/O[[:]sortorder]] [/P] [/Q] [/R] [/S] [/...


10

NTFS sort of does if you include The Encrypting File System as part of it. The Encrypting File System (EFS) on Microsoft Windows is a feature introduced in version 3.0 of NTFS Secure deletion is supported by cipher.exe: You can use the Windows Cipher utility (with the /W option) to wipe free space including that which still contains deleted plaintext ...


Only top voted, non community-wiki answers of a minimum length are eligible