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Posts tagged encryption
GPG, Mail 4.2, Snow Leopard, and Happiness
Feb 5th
I discovered Cyanide and Happiness on YouTube the other day. It’s hilarious.
Also, I found a way to use GPG signing and encryption in Apple’s Mail app.
First, quit Mail. I know it’s hard, but you can do it!
Second, back up your GPG keys and REMOVE YOUR EXISTING ~/.gnupg directory if it exists. The configuration file that already exists somehow conflicts with the pinentry app that prompts for your GPG password. I back up my keys this way:
$ gpg -a –export me@ozymo.com >> me_ozymo.com.asc$ gpg -a –export-secret-key me@ozymo.com >> me_ozymo.com.asc
Note that this will store your PRIVATE key in the file as well. This is necessary for importing, but not ideal to keep around on some random computer. Use your head.
Third, download this file. If you don’t trust me, look here on page 6. Or here. Same file. Once it downloads, drag it into ~/Library/Mail/Bundles. If there is already a GPGMail.mailbundle there, remove it and drop the new one in place.
Fourth, open Mail.
Fifth, be happy. And check out Cyanide and Happiness. It’s REALLY funny. I laughed my ass off and sewed it to a chair.
/cs
Labeling your Encrypted USB Partitions
Feb 22nd
So, the other day, I plugged in my USB drive with the encrypted partitions I created, and realized I was tired of having to wonder which one was which before checking the size or contents.
The reason it’s an issue is because I created two encrypted partitions. One is 5MB for SSH and GPG keys and whatnot, and the other is the 512M partition discussed in the article.
To alleviate the naming issue, I found the device-mapper object that corresponds to each partition and issued the following command for watch corresponding name and device-map. Device-mapper basically uses a generic process to map one block device to another:
sudo tune2fs -L nameOfEncryptedPartition /dev/mapper/Luks_crypto_partitionID
Now, when I plug in my USB drive, I am greeted with “enc1″ and “enc2″, which are the set labels for the partitions, rather than a random selection by udev labeling each as disk-N, where N is a digit.
Problem solved.
/cs
Encrypted USB with dm-crypt and LUKS
Feb 13th
Recently, I came across an issue. I wanted to transfer some information from place to place, and have access to it, and make sure that no one else had access to it.
So, why not set up an encrypted USB device?
The cryptsetup package in Ubuntu, which provides a command-line interface for configuring encrypted devices, along with the dm-crypt device-mapper target, which allows for transparent encryption of block devices using the new Linux 2.6 kernel’s cryptoapi, when combined with Linux Unified Key Setup, a USB device and a little inginuity, provide the key. And without the key specified in the setup of the encrypted device, there is no access to the data. Just what I like! So, how does one go about this seemingly-quite-complicated-and-may-take-several-tries-before-getting-it-right setup? Here’s how:
1. First things first – acquire a USB drive. I use a 4GB Lexar Firefly. It’s white.
PLEASE NOTE: If you have ANY data on the drive that you want to keep, make a backup of it right now. Where we’re going, we don’t need data. Yet.
I have it partitioned as follows (you may not need this much stuff):
$ sudo fdisk -l /dev/sda
Disk /dev/sda: 4059 MB, 4059561984 bytes
125 heads, 62 sectors/track, 1023 cylinders
Units = cylinders of 7750 * 512 = 3968000 bytesDevice Boot Start End Blocks Id System
/dev/sda1 * 1 190 736219 6 FAT16
/dev/sda2 191 320 503750 83 Linux
/dev/sda3 321 450 503750 83 Linux
/dev/sda4 451 1023 2220375 5 Extended
/dev/sda5 451 452 7719 83 Linux
/dev/sda6 453 1023 2212594 6 FAT16
To partition the drive, you can use fdisk, or gparted, or what you are comfortable with. This isn’t a tutorial for that, though, so I won’t go into more details than I have at this point. Basically, though, we need at least two partitions: One for the encrypted section, and one for regular use.
In case you are wondering why you wouldn’t want to encrypt the whole thing, read on. You don’t want to have to type your password in every time you plug it in. You want to be able to put the new driver that you downloaded on your cable internet on your Grandma’s computer so you don’t have to wait 3 hours for it to download over dialup. Your wife asks you to get the updated budget off of her computer, and you haven’t convinced her that Linux RULES! yet. I can go on for hours, but it comes down to this: If the whole thing is encrypted, it negates the usefulness of the USB drive. That said, let’s continue.
2. Install the cryptsetup package on Ubuntu using the following command (or do this on your distro the appropriate way):
# sudo apt-get install cryptsetup
3. Reboot, or load the new dm-crypt module:
# sudo modprobe dm_crypt
4. Look at /etc/fstab and see whether or not there are any entries pertaining to the USB drive, as these will likely cause it to fail to mount. Make sure that both of the partitions on the USB drive are NOT MOUNTED!! use the mount command to list your mounted devices, and see if the appropriate block device is there. If it is, unmount it:
# umount /dev/sda1
5. Create the encrypted filesystems for secure storage on the FIRST partition you created:
# sudo luksformat -t ext2 /dev/sda1
6. Create the vfat partition for normal USB drive use on the SECOND partition. I have given the partition the name LEXAR:
# sudo mkfs.vfat -n LEXAR /dev/sda2
7. If Ubuntu decided in partitioning to remount the drive, unmount it. Remove the drive from the USB slot. Reinsert the USB drive, and voila! Ubuntu will prompt you for a password in order to mount your encrypted USB partition.
Now, you have a secure place to store sensitive information, such as SSH or PGP keys, password lists, pictures of your lovely wife, or anything else you come across. Now, you can feel free to restore the data that you backed up earlier.
/cs