LinuxQuestions.org
LinuxAnswers - the LQ Linux tutorial section.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Security
User Name
Password
Linux - Security This forum is for all security related questions.
Questions, tips, system compromises, firewalls, etc. are all included here.

Notices



Reply
 
Search this Thread
Old 12-27-2012, 12:31 PM   #1
fektom
LQ Newbie
 
Registered: Dec 2012
Location: Hungary
Distribution: Debian squeeze
Posts: 2

Rep: Reputation: Disabled
Data encryption against theft


Hello everybody!

Some days ago, I got an idea to test the linux file system (ext4) on my pen drive. My purpose was to make sure, whether the files on my pen drive are accessible on other computers or not.

I cp some files to the device and changed the ownership and access rights of them.

I checked later these files, if I'm able to read them or not. Unfortunately I was able on another Linux, what more, when I was root I could change all rights and ownership features.

Well, I thought, there must be one way against theft and securing my data. I thought to encryption.

But I don't really understand the functioning of a fully encrypted drive. Does it mean, that:
1, you always have to decrypt your data with every boot? (I can imagine a program, which asks a password for decryption with every boot. And if you don't have the password you can not use your linux machine for anything. Is that right?)

2, if the man, who theft your device, connect it to his Linux-based computer, he can not see neither the contents nor the access rights. So he is not able to look what he exactly gained.

3, and if the man, who theft your device, has no idea what kind of program you used to encrypt your data has to firstly find out what was the program to crack your device?

If you have answers, please share them!
Thx!
 
Old 12-27-2012, 01:30 PM   #2
kbscores
Member
 
Registered: Oct 2011
Location: USA
Distribution: Red Hat
Posts: 259
Blog Entries: 9

Rep: Reputation: 32
RedHat uses luks - I'm pretty sure cryptsetup is available for Debian too. I know with cryptsetup you can encrypt the drive and then put in the passphrase 1 time for that box and add it to /etc/fstab. After that as long as the device is connected you will be able to see what is on it. That is contingent upon the passphrase not being changed.
 
Old 12-27-2012, 06:12 PM   #3
NyteOwl
Member
 
Registered: Aug 2008
Location: Nova Scotia, Canada
Distribution: Slackware, OpenBSD, others periodically
Posts: 512

Rep: Reputation: 139Reputation: 139
Quote:
Originally Posted by fektom View Post
Hello everybody!

Some days ago, I got an idea to test the linux file system (ext4) on my pen drive. My purpose was to make sure, whether the files on my pen drive are accessible on other computers or not.

I cp some files to the device and changed the ownership and access rights of them.

I checked later these files, if I'm able to read them or not. Unfortunately I was able on another Linux, what more, when I was root I could change all rights and ownership features.
On a removable drive, depending on where the drive is mounted will depend on who the permissions apply to. In any event, root on a given system has access to any file on the system.

Quote:
1, you always have to decrypt your data with every boot? (I can imagine a program, which asks a password for decryption with every boot. And if you don't have the password you can not use your linux machine for anything. Is that right?)
Any partitions you encrypt will remain inaccessible until mounted. Assuming LUKS, the system can mount them decrypted once supplies with the passphrase or a keyfile. You can set them up to mount decrypted automatically at boot but it somewhat defeats the purpose of encryption.

If you forget your password then the data will remain inaccessible. Unless you encrypt the root partition as well, the system should still be usable. If you encrypt the root partition and forget the password you are pretty much out of luck.

Quote:
2, if the man, who theft your device, connect it to his Linux-based computer, he can not see neither the contents nor the access rights. So he is not able to look what he exactly gained.
Correct

Quote:
3, and if the man, who theft your device, has no idea what kind of program you used to encrypt your data has to firstly find out what was the program to crack your device?
No. He can know you used LUKS (for example) and it won't do the thief any good. He could even likely know the algorithm you used and it still wouldn't help unless you use something with a known exploitable flaw.

Last edited by NyteOwl; 12-27-2012 at 06:16 PM. Reason: Fixed typos
 
1 members found this post helpful.
Old 12-27-2012, 06:12 PM   #4
jefro
Guru
 
Registered: Mar 2008
Posts: 12,087

Rep: Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521Reputation: 1521
Almost all formats are only useful when you maintain physical security. Encryption of a partition or within files does prevent access when physical security has been breached. It does not guarantee you will always have access to the data. Many a file has been lost by not having a protected backup.

There are only so many encryption schemes. There are many ways to simplify cracking and not sure there is any that some of the big governments can't crack by brute force.

Some of the simple encryption would prevent casual thief. Many of the ways can be tied to a scheme so that you never notice it's use. You can make a self signed certificate or other means to open that drive/files.

Not too long ago hardware based usb world wide company found out the hard way that their stuff was easy to crack. Assume that your choice may already be breached by skilled hackers.


http://www.truecrypt.org/

http://www.gnupg.org/


https://www.cs.arizona.edu/computing...ncryption.html
 
1 members found this post helpful.
Old 12-28-2012, 04:55 AM   #5
fektom
LQ Newbie
 
Registered: Dec 2012
Location: Hungary
Distribution: Debian squeeze
Posts: 2

Original Poster
Rep: Reputation: Disabled
They were very helpful in theory and in practice, as well! Thank you!
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is there a standard for file/data encryption? halfpower Linux - Security 5 11-19-2012 08:09 PM
Data encryption software available? samrat_rao Linux - Security 10 03-06-2009 01:43 PM
Question about data-encryption ... MyAndy Linux - Security 1 02-26-2009 08:44 AM
Data Encryption NickCoons Linux - Security 12 11-14-2007 11:17 PM
Linux password encryption and data encryption Tux-Slack Programming 4 06-20-2007 07:46 AM


All times are GMT -5. The time now is 11:27 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration