[posthumanus]

hello

i’ve just discovered ‘archiving’ documents & turning ‘em into .zip files.

when i alter permissions to ‘no access’ the computer can’t open ‘em, unless someone knows to retrace the permissions branch.

so far so good.

but what happens when i email the .zip somewhere else?

can it be opened without a nutcracker. do they need my authority?

is this a viable option for safe passage: .zipping up a password locked sparseimage.dmg.

posthumanus

[Chuckit]

E-mail does not preserve file permissions or ownership. A password-protected DMG would work and doesn't need to be zipped, though it could only be opened on another Mac as far as I'm aware.

[Big Mac]

Get a Thawte cert instead and you can encrypt your entire message that way, as long as you have the recipient's public key.

[ghporter]

PGP, or the open source GPG can both compress and encrypt files, and they are VERY secure, plus both PGP and GPG are available on multiple platforms. The "security through obscurity" angle is only useful if your stuff is only ever seen by neophytes and other uninformed persons. A real "cracker" would simply copy or email your carefully "permission-locked" file to a different context and then have full access.

[posthumanus]

thanx for that

[besson3c]

Originally Posted by Big Mac 

Get a Thawte cert instead and you can encrypt your entire message that way, as long as you have the recipient's public key.

Public key recognition is a PGP thing, not an SSL certificate/Thawte thing. If you are using free email certs, the only real authentication you get is that "somebody requested this cert". By using PGP, you can work from the web of trust that is built from people accepting and signing your public key.

If you want to email stuff securely, I recommend PGP. Gnupg/GPG is an open source PGP implementation that works quite well. You can add PGP support into both Mac OS X Mail and Mozilla Thunderbird.

[besson3c]

Originally Posted by ghporter 

PGP, or the open source GPG can both compress and encrypt files, and they are VERY secure, plus both PGP and GPG are available on multiple platforms. The "security through obscurity" angle is only useful if your stuff is only ever seen by neophytes and other uninformed persons. A real "cracker" would simply copy or email your carefully "permission-locked" file to a different context and then have full access.

Compress? Don't you mean sign and/or encrypt?

[Big Mac]

Originally Posted by besson3c 

Public key recognition is a PGP thing, not an SSL certificate/Thawte thing. If you are using free email certs, the only real authentication you get is that "somebody requested this cert". By using PGP, you can work from the web of trust that is built from people accepting and signing your public key.

Right, I was referring to Thawte's free email certs, which are functionally equivalent to PGP.

[ghporter]

Originally Posted by besson3c 

Compress? Don't you mean sign and/or encrypt?

That too, but PGP will also compress; a compressed PGP file rivals a .zip file in size.

[besson3c]

Originally Posted by ghporter 

That too, but PGP will also compress; a compressed PGP file rivals a .zip file in size.

You're right! I see that you can set the compression level via bzip2... I'm assuming that higher compression levels beyond the default require more processing time and can yield smaller files.

Cool, didn't know that.. thanks!

[besson3c]

Originally Posted by Big Mac 

Right, I was referring to Thawte's free email certs, which are functionally equivalent to PGP.

The implementation is much different, the broader goals of securing email are shared, yes.

[rehoot]

Here are my notes on creating encrypted .zip files in PKZIP format. I did this about a year ago. First, note that if you want to encrypt files for your own use, then you can use Disk Utility and the menu command to create a new image from a folder and select the encryption option and then delete the original after you verify that the encrypted version is good. Also keep a backup of this file! The resulting .dmg file might not work well if you email it to Windows users (I'm not sure).

This might have changed in OS 10.4, but on my PB with 10.3 I downloaded a program called zip-ssl using Fink
(Fink - Download Quick Start
or FinkCommander - Home ). Let Fink install it, and the program name on your computer might become zip without the -ssl. The install process might install other libraries related to ssl.

You can then create encrypted .zip files in PKZIP format using a command like:

zip -e myfile.zip myfile.txt

To unzip:
unzip myfile.zip

For others who are reading this, I'll clarify .zip versus .gz. You can create nonecrypted .zip files with ditto using a command like this:

ditto -c -k -X --rsrc some_folder some_folder.zip

The --rsrc option is needed on 10.3 to keep all file attributes but might not be needed on 10.4. If you use gzip or bzip2 the file format is not the same as .zip.

>>I just ran zip and unzip on my Mac Pro and it worked. I had installed this on the Mac Pro using Fink in September 2006.