git-mine

Yes, even git repositories are a cryptocurrency now.

Another implementation, in rust (but also using OpenCL): https://github.com/not-an-aardvark/lucky-commit

How to verify a commit hash

Assuming the commit is HEAD:

Get the first 10 digits of the (plain, ordinary) git hash: WANT=$(git rev-parse HEAD | cut -c -10)
echo $WANT
Make sure b2sum is installed. On debian it is in "coreutils".

Re-compute the git hash using sha1sum. Also do it with b2sum:

MSG=$(git cat-file commit $WANT)
for alg in sha1sum b2sum; do
  echo -n "$alg "
  ( echo -ne "commit $(( ${#MSG} + 1 ))\x00"; echo "${MSG}" ) | $alg | \
  grep $WANT
done

grep should verify for you that b2sum spit out the $WANT digits just like sha1sum. If there is no b2sum line, it means grep could not find $WANT digits in the b2sum output:

Example of a valid commit:

...
done
sha1sum aabbccddee 92dbc803c03f2f45cba7ddc5813106cf -
b2sum 4f9997f02a6091ac98d7a47d1a72468dfcda926212e2c855b0600c7b8aa82737d8e082acfea6a95ecad42836881916129c508675f58509 aabbccddee 171a74a9 -

Example of an invalid commit:

...
done
sha1sum aabbccddee 92dbc803c03f2f45cba7ddc5813106cf -

(The above is missing a b2sum line with a highlighted section, if grep can use of color.)

How to sign your commit

First commit using whatever your normal tools are.

Then from a directory inside the git repo you want to sign (a submodule is ok), run:

git cat-file commit HEAD | git-mine

Maybe a later version will change this to take the commit hash (or HEAD, etc.) as the first parameter. git-mine can run git cat-file commit $HASH as a subprocess and capture the output. To Keep It Simple, right now git-mine just expects the raw commit to be piped in.

How to sign your commit using OpenCL