shufflecake/CHANGELOG.md

Changelog

This is the changelog for shufflecake-c which is part of the Shufflecake Project. Shufflecake is a plausible deniability (hidden storage) layer for Linux. See https://www.shufflecake.net. All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[0.5.6] - 2025-11-24

Fixed

• Fixed bad performance of FLUSH requests and improved their management.
• Implemented proper handling of FUA-flagged bio's, restoring full crash consistency.

Added

• Implemented proper test units on make test.
• Introduced handling of arbitrary size I/O requests, previously limited to 4 KiB, now up to 1 MiB.
• Added a developer guide.

[0.5.5] - 2025-09-24

Fixed

• Fixed issue of bad memory allocation on some archs due to the improper use of vmalloc. The fix is experimental, as we could not reproduce the bug on RISCV architecture, so feedback is welcome.

Added

• Added explanation on how to deal with unsigned kernel modules with Secure Boot in README.md.

[0.5.4] - 2025-09-06

Fixed

• Fixed erratic behavior and improved error handling of benchmark scripts.
• Fixed typos in CHANGELOG.md.

Added

• Working garbage collection of unused slices: these can now be recovered by doing a fstrim before a shufflecake close operation.
• Workqueue processing of READ and WRITE requests made optional by default, as this improves performance in most workloads. Queues can be re-enabled on shufflecake open with --use-read-queue and --use-read-queue.
• Added one external contributor.

Changed

• New content in README.md.
• Minor edits to CONTRIBUTING.md.

[0.5.3] - 2025-07-05

Fixed

• Fixed GCC compilation error.

Refactored

• Added support to FLUSH for Shufflecake Lite and made position maps write-back.
• Removed hardcoded version string from CLI and have it correctly imported from sflc-constants.h.

Changed

• Minor edits to README.md.
• Minor edits to INSTRUCTIONS.md in the benchmark suite.

[0.5.2] - 2025-01-17

Added

• Progress status during init.
• Added CONTRIBUTING.md.
• Added one external contributor.

Fixed

• Fixed make test not working due to misnamed constants and variables.

[0.5.1] - 2024-10-13

Refactored

• Reorganized interface between dispatcher and dm-legacy through pointers to functions.

Fixed

• Fixed debug error message when reading unallocated slices on dm-legacy.

[0.5.0] - 2024-09-01

Added

• Benchmark and fragmentation scripts for Shufflecake Lite.
• Schematics for new Lite headers.

Changed

• BREAKING CHANGE: introduction of "Shufflecake Lite" scheme as default.
• BREAKING CHANGE: moved old Shufflescake scheme as "Legacy" option for backward support.
• Edited README.md to show the difference between the Lite and Legacy modes, and also added a usability warning.

Fixed

• Volumes offered by the same device now show as all related to that device with lsblk.

Refactored

• Global refactoring and simplification of code tree.
• Changed all occurrences of "Shufflecake Old" to "Shufflecake Legacy", including code paths and variables.
• Reordered entries in CHANGELOG.md with sections following the order Added -> Changed -> Fixed -> Refactored -> Removed.

[0.4.5] - 2024-06-03

Changed

• Minor edits to README.md.

Fixed

• Fixed a compile error on some new releases of LTS kernels due to the removal of a function API.
• Fixed segmentation fault when opening an already opened device.

[0.4.4] - 2023-12-31

Changed

• Variables shuffled_psi_array and shuffled_psi_ctr renamed to prmslices and prmslices_octr respectively, to be more consistent with reference paper.
• Minor edits to README.md.

Fixed

• Fixed a memory allocation error on large devices due to the use of a function not meant for allocating large amount of memory.

[0.4.3] - 2023-11-29

Fixed

• Fixed compile error on kernel version >= 6.4 due to changed behavior of DEFINE_SEMAPHORE macro.
• Fixed minor cosmetic bug on some benchmark scripts.

[0.4.2] - 2023-11-28

Changed

• All schematics and references now consistently map array indices of size N from 0 to N-1 rather than from 1 to N.

Fixed

• Fixed persistent slice allocation ambiguity after a volume corruption by allocating fresh slices for the corrupted volume. This is done in order to help external recovery tools (e.g. RAID).
• Fixed a bug that made the last PSI in the shuffled slice array unassignable.
• Fixed a missed deallocation problem which caused a kernel bug on volume close after some I/O errors.
• Fixed a buggy swap procedure which made the permutation of PSIs not completely random.

[0.4.1] - 2023-07-30

Fixed

• Fixed and improved benchmark scripts.
• Fixed mistake in drawing of doc/headers.png and doc/headers.svg.

[0.4.0] - 2023-07-24

Added

• Benchmark suite with testing tools for Shufflecake, LUKS, and VeraCrypt.
• changepwd action to change an existing password.
• checkpwd action to check if a given password is correct.
• Improved documentation in README.md on using init non-interactively.
• doc section which for now includes figure of Shufflecake header structure.

Changed

• BREAKING CHANGE: slightly modified header field format, removing redundant MAC field and making it adherent to documentation.
• Action init now reads password from secure interface (not echoing characters, etc).
• Updated instructions in SECURITY.md.

Fixed

• Fixed a bug that made --skip-randfill option not work.
• Fixed a bug that made action close not work.

Refactored

• Implemented reference slice allocation algorithm with much faster performance.

[0.3.1] - 2023-07-15

Added

• Interactive test for Argon2id KDF.
• Added in README.md a description for a manual procedure for increasing volume resistance to corruption using RAID.
• Fully functional badges images in README.md.

Fixed

• BREAKING CHANGE: fixed parameters for Argon2id KDF, which were previously set too high, resulting in slow opening for non-recent devices. Unfortunately this breaks header format compatibility with v0.3.0, so please treat v0.3.0 as bugged.

[0.3.0] - 2023-07-11

Changed

• License changed from GPLv3+ to GPLv2+.
• Switched from Scrypt to Argon2id as KDF.
• Removed (or made optional) most interaction from the action commands. Now a block device path is a mandatory argument for all actions. Moreover, some options can be passed by command line rather than asked interactively.
• One global salt for deriving keys for all headers in order to not slow down too much opening. This allows us to avoid a difficult choice between insecurity against brute-force attacks and unacceptably slow opening time.
• Added a 1-block offset to accommodate for header format change.

Fixed

• Test routines available with make test, for now limited to low-level crypto operations.

Refactored

• Unified repositories of kernel module and userland tool into a single one. Makefile, docs, etc unified accordingly.
• Adopting SemVer as of release v0.3.0.
• Program version now defined within sflc_constants.h.
• CLI built with argp.h and following GNU behavior.

[0.2.0] - 2023-04-17

Added

• Automatic procedural naming of open volumes.
• Support larger volumes with headers of variable size.
• Add interactive option to skip random filling during init.

Changed

• Switch from libsodium to libgcrypt.
• Change header format.
• Change syntax of commands.
• Switch to Scrypt KDF.

Fixed

• Compile correctly on Linux kernel 6.1.

Removed

• Removed flag --no-randfill.

[0.1.0] - 2022-11-10

This is the first release of shufflecake-c.