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   cryptsetup    ( 8 )

управлять обычными dm-crypt и зашифрованными томами LUKS (manage plain dm-crypt and LUKS encrypted volumes)
  Name  |  Synopsis  |  Description  |  Plain dm-crypt or luks?  |  Warning  |  Basic actions  |  Plain mode  |  Luks extension  |  Loop-aes extension  |  Tcrypt (truecrypt-compatible and veracrypt) extension  |  Bitlk (windows bitlocker-compatible) extension (experimental)  |  Miscellaneous  |  Options  |  Examples  |  Return value  |  Notes on passphrase processing for plain mode  |  Notes on passphrase processing for luks  |  Incoherent behavior for invalid passphrases/keys  |  Notes on supported ciphers, modes, hashes and key sizes  |  Notes on passphrases  |  Notes on random number generators  |    Authenticated disk encryption (experimental)    |  Notes on loopback device use  |  Luks2 header locking  |  Deprecated actions  |  Reporting bugs  |

AUTHENTICATED DISK ENCRYPTION (EXPERIMENTAL)

Since Linux kernel version 4.12 dm-crypt supports authenticated disk encryption.

Normal disk encryption modes are length-preserving (plaintext sector is of the same size as a ciphertext sector) and can provide only confidentiality protection, but not cryptographically sound data integrity protection.

Authenticated modes require additional space per-sector for authentication tag and use Authenticated Encryption with Additional Data (AEAD) algorithms.

If you configure LUKS2 device with data integrity protection, there will be an underlying dm-integrity device, which provides additional per-sector metadata space and also provide data journal protection to ensure atomicity of data and metadata update. Because there must be additional space for metadata and journal, the available space for the device will be smaller than for length-preserving modes.

The dm-crypt device then resides on top of such a dm-integrity device. All activation and deactivation of this device stack is performed by cryptsetup, there is no difference in using luksOpen for integrity protected devices. If you want to format LUKS2 device with data integrity protection, use --integrity option.

Since dm-integrity doesn't support discards (TRIM), dm-crypt device on top of it inherits this, so integrity protection mode doesn't support discards either.

Some integrity modes requires two independent keys (key for encryption and for authentication). Both these keys are stored in one LUKS keyslot.

WARNING: All support for authenticated modes is experimental and there are only some modes available for now. Note that there are a very few authenticated encryption algorithms that are suitable for disk encryption. You also cannot use CRC32 or any other non- cryptographic checksums (other than the special integrity mode "none"). If for some reason you want to have integrity control without using authentication mode, then you should separately configure dm-integrity independently of LUKS2.