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Cryptsetup 2.3.0 Release Notes
==============================
Stable release with new experimental features and bug fixes.
Cryptsetup 2.3 version introduces support for BitLocker-compatible
devices (BITLK format). This format is used in Windows systems,
and in combination with a filesystem driver, cryptsetup now provides
native read-write access to BitLocker Full Disk Encryption devices.
The BITLK implementation is based on publicly available information
and it is an independent and opensource implementation that allows
one to access this proprietary disk encryption.
Changes since version 2.2.2
~~~~~~~~~~~~~~~~~~~~~~~~~~~
* BITLK (Windows BitLocker compatible) device access
BITLK userspace implementation is based on the master thesis and code
provided by Vojtech Trefny. Also, thanks to other opensource projects
like libbde (that provide alternative approach to decode this format)
we were able to verify cryptsetup implementation.
NOTE: Support for the BITLK device is EXPERIMENTAL and will require
a lot of testing. If you get some error message (mainly unsupported
metadata in the on-disk header), please help us by submitting an issue
to cryptsetup project, so we can fix it. Thank you!
Cryptsetup supports BITLK activation through passphrase or recovery
passphrase for existing devices (BitLocker and Bitlocker to Go).
Activation through TPM, SmartCard, or any other key protector
is not supported. And in some situations, mainly for TPM bind to some
PCR registers, it could be even impossible on Linux in the future.
All metadata (key protectors) are handled read-only, cryptsetup cannot
create or modify them. Except for old devices (created in old Vista
systems), all format variants should be recognized.
Data devices can be activated read-write (followed by mounting through
the proper filesystem driver). To access filesystem on the decrypted device
you need properly installed driver (vfat, NTFS or exFAT).
Foe AES-XTS, activation is supported on all recent Linux kernels.
For older AES-CBC encryption, Linux Kernel version 5.3 is required
(support for special IV variant); for AES-CBC with Elephant diffuser,
Linux Kernel 5.6 is required.
Please note that CBC variants are legacy, and we provide it only
for backward compatibility (to be able to access old drives).
Cryptsetup command now supports the new "bitlk" format and implement dump,
open, status, and close actions.
To activate a BITLK device, use
# cryptsetup open --type bitlk <device> <name>
or with alias
# cryptsetup bitlkOpen <device> <name>
Then with properly installed fs driver (usually NTFS, vfat or exFAT),
you can mount the plaintext device /dev/mapper<name> device as a common
filesystem.
To print metadata information about BITLK device, use
# crypotsetup bitlkDump <device>
To print information about the active device, use
# cryptsetup status <name>
Example (activation of disk image):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Recent blkid recognizes BitLocker device,just to verity
# blkid bitlocker_xts_ntfs.img
bitlocker_xts_ntfs.img: TYPE="BitLocker"
# Print visible metadata information (on-disk, form the image)
# cryptsetup bitlkDump bitlocker_xts_ntfs.img
Info for BITLK device bitlocker_xts_ntfs.img.
Version: 2
GUID: ...
Created: Wed Oct 23 17:38:15 2019
Description: DESKTOP-xxxxxxx E: 23.10.2019
Cipher name: aes
Cipher mode: xts-plain64
Cipher key: 128 bits
Keyslots:
0: VMK
GUID: ...
Protection: VMK protected with passphrase
Salt: ...
Key data size: 44 [bytes]
1: VMK
GUID: ...
Protection: VMK protected with recovery passphrase
Salt: ...
Key data size: 44 [bytes]
2: FVEK
Key data size: 44 [bytes]
# Activation (recovery passphrase works the same as password)
# cryptsetup bitlkOpen bitlocker_xts_ntfs.img test -v
Enter passphrase for bitlocker_xts_ntfs.img:
Command successful.
# Information about the active device
# cryptsetup status test
/dev/mapper/test is active.
type: BITLK
cipher: aes-xts-plain64
keysize: 128 bits
...
# Plaintext device should now contain decrypted NTFS filesystem
# blkid /dev/mapper/test
/dev/mapper/test: UUID="..." TYPE="ntfs"
# And can be mounted
# mount /dev/mapper/test /mnt/tst
# Deactivation
# umount /mnt/tst
# cryptsetup close test
* Veritysetup now supports activation with additional PKCS7 signature
of root hash through --root-hash-signature option.
The signature uses an in-kernel trusted key to validate the signature
of the root hash during activation. This option requires Linux kernel
5.4 with DM_VERITY_VERIFY_ROOTHASH_SIG option.
Verity devices activated with signature now has a special flag
(with signature) active in device status (veritysetup status <name>).
Usage:
# veritysetup open <data_device> name <hash_device> <root_hash> \
--root-hash-signature=<roothash_p7_sig_file>
* Integritysetup now calculates hash integrity size according to algorithm
instead of requiring an explicit tag size.
Previously, when integritysetup formats a device with hash or
HMAC integrity checksums, it required explicitly tag size entry from
a user (or used default value).
This led to confusion and unexpected shortened tag sizes.
Now, libcryptsetup calculates tag size according to real hash output.
Tag size can also be specified, then it warns if these values differ.
* Integritysetup now supports fixed padding for dm-integrity devices.
There was an in-kernel bug that wasted a lot of space when using metadata
areas for integrity-protected devices if a larger sector size than
512 bytes was used.
This problem affects both stand-alone dm-integrity and also LUKS2 with
authenticated encryption and larger sector size.
The new extension to dm-integrity superblock is needed, so devices
with the new optimal padding cannot be activated on older systems.
Integritysetup/Cryptsetup will use new padding automatically if it
detects the proper kernel. To create a compatible device with
the old padding, use --integrity-legacy-padding option.
* A lot of fixes to online LUKS2 reecryption.
* Add crypt_resume_by_volume_key() function to libcryptsetup.
If a user has a volume key available, the LUKS device can be resumed
directly using the provided volume key.
No keyslot derivation is needed, only the key digest is checked.
* Implement active device suspend info.
Add CRYPT_ACTIVATE_SUSPENDED bit to crypt_get_active_device() flags
that informs the caller that device is suspended (luksSuspend).
* Allow --test-passphrase for a detached header.
Before this fix, we required a data device specified on the command
line even though it was not necessary for the passphrase check.
* Allow --key-file option in legacy offline encryption.
The option was ignored for LUKS1 encryption initialization.
* Export memory safe functions.
To make developing of some extensions simpler, we now export
functions to handle memory with proper wipe on deallocation.
* Fail crypt_keyslot_get_pbkdf for inactive LUKS1 keyslot.
Libcryptsetup API extensions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The libcryptsetup API is backward compatible for existing symbols.
New symbols
crypt_set_compatibility
crypt_get_compatibility;
crypt_resume_by_volume_key;
crypt_activate_by_signed_key;
crypt_safe_alloc;
crypt_safe_realloc;
crypt_safe_free;
crypt_safe_memzero;
New defines introduced :
CRYPT_BITLK "BITLK" - BITLK (BitLocker-compatible mode
CRYPT_COMPAT_LEGACY_INTEGRITY_PADDING - dm-integrity legacy padding
CRYPT_VERITY_ROOT_HASH_SIGNATURE - dm-verity root hash signature
CRYPT_ACTIVATE_SUSPENDED - device suspended info flag
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