57 lines
1.7 KiB
Text
57 lines
1.7 KiB
Text
dm-crypt
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=========
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Device-Mapper's "crypt" target provides transparent encryption of block devices
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using the kernel crypto API.
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Parameters: <cipher> <key> <iv_offset> <device path> <offset>
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<cipher>
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Encryption cipher and an optional IV generation mode.
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(In format cipher[:keycount]-chainmode-ivopts:ivmode).
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Examples:
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des
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aes-cbc-essiv:sha256
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twofish-ecb
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/proc/crypto contains supported crypto modes
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<key>
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Key used for encryption. It is encoded as a hexadecimal number.
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You can only use key sizes that are valid for the selected cipher.
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<keycount>
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Multi-key compatibility mode. You can define <keycount> keys and
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then sectors are encrypted according to their offsets (sector 0 uses key0;
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sector 1 uses key1 etc.). <keycount> must be a power of two.
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<iv_offset>
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The IV offset is a sector count that is added to the sector number
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before creating the IV.
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<device path>
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This is the device that is going to be used as backend and contains the
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encrypted data. You can specify it as a path like /dev/xxx or a device
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number <major>:<minor>.
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<offset>
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Starting sector within the device where the encrypted data begins.
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Example scripts
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===============
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LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
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encryption with dm-crypt using the 'cryptsetup' utility, see
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http://code.google.com/p/cryptsetup/
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[[
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#!/bin/sh
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# Create a crypt device using dmsetup
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dmsetup create crypt1 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
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]]
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[[
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#!/bin/sh
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# Create a crypt device using cryptsetup and LUKS header with default cipher
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cryptsetup luksFormat $1
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cryptsetup luksOpen $1 crypt1
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]]
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