Note: This page is horribly out of
date.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...
Healing, once we decided we wanted it, moved at the speed of practicalities and apologies. We re-drew boundaries not as punitive lines but as scaffolding: agreed times for visitors, clear expectations about chores and respect, and — crucially — conversations where no one’s history was minimized. The boy began to understand that belonging cannot be demanded only by perseverance; it must be earned by respect. My husband began to see that care sometimes requires choosing between being kind and being fair. I relearned that generosity without limits can become a suffocating thing.
What fascinates me most about being the outsider-turned-partner in this story is the way it reframes what home even means. Home is not a static blueprint you enter and inhabit; it is a negotiation, a shifting architecture of need and dignity. People come into it not as whole works but as drafts, and you either accept the editing or you refuse to play a part at all.
The first time I noticed the signs, they were small and almost tender — a sneaker tread in the dewy grass, a whisper of voices behind the thin wall, the faint flicker of a phone screen under the covers long after lights-out. At first I told myself it was imagination: the house is old, my mind tired, the everyday creaks made strange by a restless sleep. But then the pattern formed, patient and deliberate, like someone drawing a map in the margins of my life.
Confrontation arrived like a storm. It was not the cinematic blowout of slammed doors and shouted accusations; instead it was a quieter, more dangerous thing — the unspooling of small resentments into a conversation that asked everything. I told my husband how it feels to lose turf in your own home, how invisible decisions stitch themselves into the fabric of daily life until you are no longer sure where you end and other people begin. He listened, and in his listening I saw the honest confusion of a man who believed he had only been doing right.
My husband saw him differently. Where I felt invaded, he felt obliged. Love, when mixed with duty, can make you blind to the boundaries that keep people whole. He offered second chances like currency: a ride to school, a lasagna on Sundays, a shoulder for grievances I hadn't heard. He built bridges across years of absence without asking whether the foundations were wanted. The boy crossed them like a conqueror, blinking in the light of a new allegiance.
I learned the etiquette of compromise in increments. I learned to count my spoons less greedily. I learned that patience can be a slow erosion, that conceding once becomes a habit if not consciously guarded. I started measuring my life in tolerances: how much noise I could endure before my teeth ached, how many unasked-for guests I could feed before my appetite soured. Each concession was a soft opening for the next intrusion. A towel unreturned. A door left ajar. A secret held between father and son that excluded me by design.
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.
Healing, once we decided we wanted it, moved at the speed of practicalities and apologies. We re-drew boundaries not as punitive lines but as scaffolding: agreed times for visitors, clear expectations about chores and respect, and — crucially — conversations where no one’s history was minimized. The boy began to understand that belonging cannot be demanded only by perseverance; it must be earned by respect. My husband began to see that care sometimes requires choosing between being kind and being fair. I relearned that generosity without limits can become a suffocating thing.
What fascinates me most about being the outsider-turned-partner in this story is the way it reframes what home even means. Home is not a static blueprint you enter and inhabit; it is a negotiation, a shifting architecture of need and dignity. People come into it not as whole works but as drafts, and you either accept the editing or you refuse to play a part at all. video title my husbands stepson sneaks into o
The first time I noticed the signs, they were small and almost tender — a sneaker tread in the dewy grass, a whisper of voices behind the thin wall, the faint flicker of a phone screen under the covers long after lights-out. At first I told myself it was imagination: the house is old, my mind tired, the everyday creaks made strange by a restless sleep. But then the pattern formed, patient and deliberate, like someone drawing a map in the margins of my life. Healing, once we decided we wanted it, moved
Confrontation arrived like a storm. It was not the cinematic blowout of slammed doors and shouted accusations; instead it was a quieter, more dangerous thing — the unspooling of small resentments into a conversation that asked everything. I told my husband how it feels to lose turf in your own home, how invisible decisions stitch themselves into the fabric of daily life until you are no longer sure where you end and other people begin. He listened, and in his listening I saw the honest confusion of a man who believed he had only been doing right. My husband began to see that care sometimes
My husband saw him differently. Where I felt invaded, he felt obliged. Love, when mixed with duty, can make you blind to the boundaries that keep people whole. He offered second chances like currency: a ride to school, a lasagna on Sundays, a shoulder for grievances I hadn't heard. He built bridges across years of absence without asking whether the foundations were wanted. The boy crossed them like a conqueror, blinking in the light of a new allegiance.
I learned the etiquette of compromise in increments. I learned to count my spoons less greedily. I learned that patience can be a slow erosion, that conceding once becomes a habit if not consciously guarded. I started measuring my life in tolerances: how much noise I could endure before my teeth ached, how many unasked-for guests I could feed before my appetite soured. Each concession was a soft opening for the next intrusion. A towel unreturned. A door left ajar. A secret held between father and son that excluded me by design.
Please contact the mailing list: dm-crypt@saout.de. Or in case there is a problem with the mailing list, me: .