Originally Posted by FEAST Network encryption:
Wouldn't the point of using 3 layers of encryption be to ensure that no one intercepts the keys?
No, because the key is kept on your end. In the case of ssh, you use a keypair. One of them is a public key meaning anyone can have it and it doesn't matter. The other half is the private key and is kept on your end. This is the key that should be well guarded by a strong password. You should really do some reading
on public key crypto so you understand how it works. It's not hard to understand, but it's important that anyone who uses public-key crypto (RSA/DSA keys usually) understands what they're doing and why things are done the way they are. Knowledge is power in crypto.
One important thing to remember is never to try to come up with your own solutions. You are not an expert. Crypto is a VERY complicated field full of high level mathematics and lots of software intricacies. Leave it to the professionals to come up with the solutions. PGP/GnuPG, SSH, etc are professionally written and should be relied on as they are.
the main vulnerability would be someone getting a hold of you sftp server keyfile - or getting a hold of your vpn key, or your local encryption key. All of these keys could potentially be intercepted, or engineered out of someone, yes?
You should be using a password along with a keyfile really. That way even if someone has physical access to your machine they can't compromise your private keys (the private key itself is encrypted with a symmetric cipher. The key to that cipher is a password. If the private key is not encrypted, it is there for anyone to take). A lot of SSH users are lazy and do not encrypt their private key because they are too lazy to enter the password every time. This means anyone who can hack their machine can have the keys to the kingdom.
I do need a continuous connection - and am currently using SSH/SFTP.
Use one or the other. No need to use both. I fail to see what that accomplishes. SSH really works just like e-mail encryption -- it uses a public/private keypair. The private key is what you should be protecting.
As for bitlocker. You are vulnerable if they have access to your mobo/stored key...is there any way to store your key on say a USB drive and require a 4-digit pin? So that you aren't really vulnerable? Also, preferably 2 usb drives - in case I lose one?
disk encryption program can be compromised if an attacker has physical access to your machine. He can install a keylogger to catch keystrokes. Or he can perform the "evil maid attack" which means he compromises your bootloader and installs a fake bootloader which captures your pre-boot passphrase to unlock the drive. Or, let's say you leave your machine on and leave it. In that case he can perform a cold boot attack, which means he simply takes the key from your RAM. Bruce Schneier (one of the foremost crypto experts) gives a good overview of these attacks here
, and discusses possible preventative measures. Basically the only way to prevent this is if your machine has a TPM chip. However, even those chips have been hacked already (though hacking them is much harder than the other attacks).
Bottom line: The only time drive encryption is safe is when the machine is powered off completely. And even then you must ensure no one has been physically tampering with your machine over a period of time while it was booted.
I use software encryption on the files I use to store my passwords in. Usual an excel spreadsheet. I use excel's password feature. Is this secure?
You're much better off using software designed for this purpose. Keepass
is probably the best. It does basically what you're doing but automates it and makes things much easier to manage. it is also open-source and free to use for no charge.
The thing that really sucks about software encryption is the cleanup. Windows loves to cache and store recently opened data, indexing, etc etc. Also, disk cleanup programs have ERASED encrypted files of mine in the past....
Yes, if you are only encrypting individual files/folders, then you always run the risk of the unencrypted versions of those files being stored somewhere in plaintext (say a swap file or temporary file for instance). It is a problem. The best way to stop that is to encrypt the ENTIRE operating system. Bitlocker and trucerypt can both do this. But even then you must ensure physical security of your machine as I explained above.
If encryption works so good how come people put their drives on thermite? Lol...
Because most people are ignorant of how things really work, so they just take the most paranoid measures. In reality there is no need to physically destroy a drive. One pass of random data scrubbing will make any data completely irretrievable. This is a fact no matter what the paranoid people tell you.Edited by thiussat - 4/18/12 at 7:21pm