Git with SHA1 collision attack mitigation

This is Git with an ad-hoc (read: hacky and not upstreamable as-is) integration of the SHA1 collision attack detection from https://github.com/cr-marcstevens/sha1collisiondetection.

It replaces the SHA1 hash function used by git and aborts if suspicious data is hashed.

EXPERIMENTAL: Use at your own risk!

Building

You can build it like vanilla Git. You need to install libtool since this is used by the sha1collisiondetection lib.

Only tested on amd64 Linux (Works probably also on other platforms supported by git).

Checking already clones repos

If you want to check an already cloned repo you can fun an 'fsck'

git fsck --full

(--full might generate problems with old repos, see the manpage)

BTW

If you use this you want probably also enable more fsck-ing if you don't have already

git config --global transfer.fsckobjects true
git config --global fetch.fsckobjects true
git config --global receive.fsckobjects true

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Original Git README:

Git - fast, scalable, distributed revision control system

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.

Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.

Please read the file INSTALL for installation instructions.

Many Git online resources are accessible from http://git-scm.com/ including full documentation and Git related tools.

See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.

CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).

The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git, http://marc.info/?l=git and other archival sites.

The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.

The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):

• random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
• stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
• "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
• "goddamn idiotic truckload of sh*t": when it breaks