IntegrityChecker v0.1

ichk is a simple file integrity tool written in Python.

Tool created for me but can be used also by data hoarders and all peoples who are interested in periodically checking file hashes. Maybe in future this tool will be something more, but for now it just calculating file hashes.

Tool is suitable only for immutable files.

This is done as hobby side project - so many fancy things is missing or even you will find some ugly code inside :)

Basic functionality

List of basic functionality of the tool.

Calculate file hash

It can calculate hash of specified file or files and print it to stdout. For now it only supports XXH128 and OSHASH as currently most efficient solution which I know.

File size and OSHASH are for fast check if file was altered after setting extended attributes. This isn't perfect, because it only verifies file size and some part of the file (OSHASH).

Set file extended attributes

There is possibility to set files extended attributes with calculated hashes. It will store data under user.ichk.* entries:

• user.ichk.fsize - file size at the scan moment
• user.ichk.xxh128 - XXH128 hash written as an ASCII HEX
• user.ichk.oshash - OSHASH has written as an ASCII HEX

Verify file hash

Tool will calculate hash of the file and verify with data written inside file extended attributes. Done only when file has attributes set and fast check is OK.

Get file hash

It differs from calculation - because it will just get XXH128 hash from extended file attributes after verification of file size and OSHASH.

Update file

After altering file user should execute updating file hashes, because it will have invalid hash data written in extended file attributes.

Lock file

This functionality will try to set file attributes to read-only and set immutable bit. In general it depends on file system and user grants.

To set file immutability - tool needs to be run under root user.

Arguments list

TODO

Arguments cheat-sheet

• all - done for all files
• no-xattr - done for all files without user.ichk extended attributes set
• xattr - done for all files with user.ichk extended attributes set without checking validity
• ok-xattr - done for all files with valid (file size and OSHASH) user.ichk attributes set

description	arguments set	calc hash	calc oshash	set xattrs	lock
calculate hashes and display to stdout	none	all	yes	no	no
calculate hashes for new files and display to stdout	-c	no-xattr	yes	no	no
display hashes from extended attributes	-g	no	yes	no	no
display hashes from extended attributes and calculate for new files	-gc	no-xattr	all	no	no
calculate hashes for new files and set extended attributes	-cs	no-xattr	no-xattr	yes	no
calculate hashes for new files, set extended attributes and lock file	-csl	no-xattr	no-xattr	yes	yes
calculate hashes for new files and update extended attributes	-cu	no-xattr	yes	no	no
verify hashes	-v	xattr	xattr	no	no
verify hashes and lock file	-vl	xattr	xattr	no	yes

Presets

Presets contains all shown flags so it will be easier to use. Additionally to provided arguments you should also add argument with files list or provide them thru stdin.

Scan

This will be a good starting point for first run on files and also for scanning new files. This command will show you only progress bars without writing all hashes into stdout.

In result all provided new files (without extended attributes set) will be locked and have extended atrributes set with calculated hashes.

• Preset form

ichk --scan

• Short form

ichk -qpcsl

• Long form

ichk --quiet --progress --calculate --set-xattr --lock-file

Verify

This will verify all already calculates files which have extended attributes set. This command will show you only progress bars without writing all hashes into stdout but stderr will have errors if verification will fail.

• Preset form

ichk --verify

• Short form

ichk -qpvl

• Long form

ichk --quiet --progress --verify-xattr --lock-file

Scan new and verify existing

You can also scan new files and verify existing ones in one pass.

• Preset form

ichk --scan --verify

• Short form

ichk -qpcslv

• Long form

ichk --quiet --progress --calculate --set-xattr --lock-file --verify-xattr

TODO

This still is in plans:

• support for cooperation with Cronicle (script + proper JSON output with stats and progress)
• test on some bigger data
• update this readme file
• clean the code
• do some release and build as standalone app