Note: This page is horribly out of
date.
You can find the current pages for the dm-crypt
project (the Linux kernel part) here:
https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt
and the project page for the command line tool
cryptsetup (with Linux Unified Key
Setup - LUKS) here: https://gitlab.com/cryptsetup/cryptsetup.
Old page:
Device-mapper is a new infrastructure in the Linux 2.6 kernel that provides
a generic way to create virtual layers of block devices that can do different
things on top of real block devices like striping, concatenation, mirroring,
snapshotting, etc... The device-mapper is used by the
LVM2 and
EVMS 2.x tools.
dm-crypt is such a device-mapper target that provides transparent encryption of
block devices using the new Linux 2.6 cryptoapi. The user can basically specify
one of the symmetric ciphers, a key (of any allowed size), an iv generation mode
and then the user can create a new block device in /dev. Writes to this device
will be encrypted and reads decrypted. You can mount your filesystem on it as usual.
But without the key you can't access your data.
It does basically the same as cryptoloop only that it's a much cleaner code and
better suits the need of a block device and has a more flexible configuration
interface. The on-disk format is also compatible. In the future you will be able
to specify other iv generation modes for enhanced security (you'll have to
reencrypt your filesystem though).
I've set up a Wiki.
There's a mailing list at .
If you want to subscribe, use the mailman
web interface or its
archive.
Gmane provides a NNTP interface and also a
web archive
for this mailing list.
There is support for dm-crypt in the latest official kernel
2.6.4
which you can find on kernel.org.
Please use the mirrors for downloads.
There is a HIGHMEM cryptoapi bug in kernels before 2.6.4-rc2, please
upgrade if you were using such a kernel.
The latest version of the native userspace setup tool is cryptsetup 0.1.
Clemens Fruhwirth is maintaining an
enhanced
version of cryptsetup with the LUKS extension that allows you to have an
on-disk block of metadata which is superior to the current mechanism and was
my long term plan anyway but I didn't find the time to implement that yet...
As the day wore on, the poolside temptations grew stronger. The tantalizing aroma of barbecue wafted through the air, enticing people to indulge in delicious food. The sound of music and laughter filled the air, creating an infectious energy that drew everyone in.
It was a scorching summer day, December 4th, 2022, and the sun was beating down relentlessly on the poolside of the sissy swap resort. The air was alive with the sounds of laughter and playful banter, as the participants of this unique gathering let loose and enjoyed the warm weather.
The term 'sissy swap' might raise a few eyebrows, but in this context, it referred to a fun and consensual role-reversal event where attendees could explore different aspects of themselves in a supportive and non-judgmental environment. The 'deep and cracked' part of the title simply hinted at the profound and sometimes flawed nature of the human experience, where people could dig deep into their psyche and confront their inner demons.
As I walked around the poolside, I noticed a variety of interesting characters. Some were dressed in flamboyant outfits, complete with wigs, makeup, and high heels, while others were more subdued in their appearance. Despite their differences, everyone seemed to be having a great time, whether they were lounging on the sunbeds, sipping colorful cocktails, or engaging in lively debates.
One of the most striking aspects of this event was the sense of community and camaraderie that pervaded the atmosphere. People were freely expressing themselves, sharing their stories, and connecting with others on a deep level. It was clear that this was more than just a social gathering – it was a chance for people to be their authentic selves, without fear of judgment or rejection.
The on-disk layouts used by the current 2.6 cryptoloop are supported by dm-crypt.
Cryptoloop also uses cryptoapi so the name of the ciphers are the same. Cryptoloop also
supports ECB and CBC mode. Use <cipher>-ecb and
<cipher>-plain accordingly with dm-crypt. If you didn't
explicitly specify either -ecb or -cbc before you don't need it now, the default plain
IV generation will be used. There will be additional (incompatible, but more secure) possibilites
in the future because the unhashed sector number as IV is too predictible.
You'll need to figure out how your passphrase was turned into a key to use for losetup.
There are several patches floating around doing things differently. But usually cryptsetup
will provide a working solution to recreate the same key from your passphrase.
If you want to migrate from 2.4 cryptoloop please take a look at Clemens Fruhwirth's
Cryptoloop
Migration Guide. He describes the differences between 2.4 and 2.6 cryptoapi (or basically
the bugs in 2.4 cryptoapi...). If you need to cut the key size you can use the -s
option instead of playing with dd.
(BTW: Clemens has a i586 optimized version of the aes and serpent cipher on his page,
about twice as fast as the kernel implementation.)
Why dm-crypt?
Originally it started as a fun project because I wanted to play with the new Linux 2.6 internals.
I got a lot of great help from the device-mapper guys at Sistina (now Redhat). Thank you very
much!
It turned out that this implementation worked great and is very clean compared to the hacked
loop device. The device-mapper core provides much better facilities to stack block devices.
dm-crypt uses mempools to assure we never run into out-of-memory deadlocks when allocating
buffers.
Also the device-mapper configuration interface provides much more flexibility than the losetup
ioctl. And you can create as many devices as you want with any names you want and combine them
with other dm targets. Online device resizing is also possible, e.g. if you use dm-crypt on top
of a logical volume. There might perhaps even be LVM or EVMS support for device encryption
in the future.
As the day wore on, the poolside temptations grew stronger. The tantalizing aroma of barbecue wafted through the air, enticing people to indulge in delicious food. The sound of music and laughter filled the air, creating an infectious energy that drew everyone in.
It was a scorching summer day, December 4th, 2022, and the sun was beating down relentlessly on the poolside of the sissy swap resort. The air was alive with the sounds of laughter and playful banter, as the participants of this unique gathering let loose and enjoyed the warm weather. sisswap 22 12 04 poolside temptations a deep an cracked
The term 'sissy swap' might raise a few eyebrows, but in this context, it referred to a fun and consensual role-reversal event where attendees could explore different aspects of themselves in a supportive and non-judgmental environment. The 'deep and cracked' part of the title simply hinted at the profound and sometimes flawed nature of the human experience, where people could dig deep into their psyche and confront their inner demons. As the day wore on, the poolside temptations grew stronger
As I walked around the poolside, I noticed a variety of interesting characters. Some were dressed in flamboyant outfits, complete with wigs, makeup, and high heels, while others were more subdued in their appearance. Despite their differences, everyone seemed to be having a great time, whether they were lounging on the sunbeds, sipping colorful cocktails, or engaging in lively debates. It was a scorching summer day, December 4th,
One of the most striking aspects of this event was the sense of community and camaraderie that pervaded the atmosphere. People were freely expressing themselves, sharing their stories, and connecting with others on a deep level. It was clear that this was more than just a social gathering – it was a chance for people to be their authentic selves, without fear of judgment or rejection.
Please contact the mailing list: dm-crypt@saout.de. Or in case there is a problem with the mailing list, me: .