gmanfunky/commit-vanity

A test repo for screwing with git commit IDs

baddify_commit.rb

Usage

$ git add baddify-commit.sh
$ git commit -m "bad update for a little more readability"

$ ruby baddify_commit.rb bad

   $ git push
   Counting objects: 3, done.
   Delta compression using up to 8 threads.
   Compressing objects: 100% (3/3), done.
   Writing objects: 100% (3/3), 578 bytes | 578.00 KiB/s, done.
   Total 3 (delta 1), reused 0 (delta 0)
   remote: Resolving deltas: 100% (1/1), completed with 1 local object.
   To https://github.com/gmanfunky/commit-vanity.git
      bad1388..bad82da  master -> master

Optionally use as a git hook

$ cp baddify_commit.rb .git/hooks/post-commit

Performance

The ruby script is much more performant than the .sh.

A chosen 5-hex-character desired prefix (e.g., 31337) may only take a couple seconds to complete. For a longer prefix, multiply this by 16 for each additional character to get rough idea of how long it might take to complete.

Questions

Can i add history before first null commit 000000000000 ?
Stretch - Be able to "fixup" after a rebase. Changes all the commits to target. (e.g., baddify-commits.sh HEAD^4)
Merge commits can have two parents. gpgsig after committer before message. Can we handle this? Can we achieve commit-vanity using additional bullshit parent commit?
~~[ ] Are there usable git libraries call quickly?~~
Can I add or remove files or various whitespace to calculate different pretty git commit SHA1?
~~Maybe use tons of file move commands to generate new commits? ~~
~~Maybe mess with the author info. Multiple author entries? Or timestamp changes. Or timestamp+timezone changes? (add to timestamp, change offset). ~~
Super dumb hack: just keep ammending last commit until getting what we want
git commit --allow-empty allows same tree. Might be used to make a short story with SHA1?. Doesn't trigger post-commit
How to cleanup stale objects? git -c gc.reflogExpireUnreachable=0 -c gc.pruneExpire=now gc
Generate and edit file directly? Read last commit, loop making new ones until ready to replace log
Maybe munge author (not committer) details. Author timestamp seems least noticable on github.com
What happens on github is timezone is not recognized (e.g., +0111 or +0199 gnarly!)
- for invalid offsets 60+ minutes, it seems git commandline will default to commit time?
- Github seems to auto-fixup author date, and ignore committer date when displaying commit details.
  so have fun with the commit time?

Hookify

Can copy to be the lesser-known .git/hooks/post-commit hook.

Quick Math

# 3 base 16 digit permutations. Want something like "bad"
$ echo $((16 * 16 * 16))
4096

Fun Short Hex Words

bad
fed
decaf
abe
dead
ca7 # caT?
d06 # Nice and trolly for them cat people?
abcd
ace
beef
face
babe
eff
effed
1337
00f
f00
fab # Code must be fabulous. ¯\_(ツ)_/¯
a11ace
babb1e
baddad
d0ab1e
d00dad
fa1afe1 (~1-8 minutes?). Save for the hsitory-rewrite feature.

Additional Reference: http://www.nsftools.com/tips/HexWords.htm

How is a git commit sha1 formed

See https://gist.github.com/masak/2415865

$ (printf "commit %s\0" $(git cat-file commit HEAD | wc -c); git cat-file commit HEAD) | sha1sum.exe ; git log | head -1
dc9decb23a96ebc4090aee1df73d50f2c31f2e9c *-
commit b23e9b68becf18bad0c7649d04ddfc8e7af27b05

Hacky PoC Commands

GIT_COMMITTER_DATE='2000-01-01T00:00:00+0000' git commit --date='2000-01-01T00:00:00+0000'

gmanfunky / commit-vanity