git-vain

Generate vanity commit hashes quickly.

Supports:

• pgp signing (via gpg-agent or sequoia)
• integration with system key store for saving pgp passwords (sequoia only)
• arbitrary commits from history
• various methods (date increment/decrement, random text, counter text, header)
• multithreading
• config file for saving common options

Install

Download the latest release or build from source using cargo.

Make sure git-vain is in your $PATH or running git vain won't work.

To build from source, run cargo install --path . or cargo build --release in your local checkout.

Usage

Replace the hash of the commit at HEAD with one that begins with c0ffee: git vain c0ffee

Try using --help for more information.

Performance

Performance depends on hardware, method, and number of threads. The tests below were performed on an AMD Ryzen 7 3800X 8-Core Processor. Each result is the average of three trials running for 30 seconds using a single thread.

  counter: 154,293,195.67 hashes (5,143,106.52/s)
   random: 134,886,025.00 hashes (4,496,200.83/s)
   header: 131,035,925.67 hashes (4,367,864.19/s)
increment:  95,501,212.00 hashes (3,183,373.73/s)
decrement:  95,358,885.33 hashes (3,178,629.51/s)
 sequoia*:     839,872.67 hashes (   27,995.76/s)
  sequoia:     330,972.67 hashes (   11,032.42/s)
gpg-agent:         113.67 hashes (        3.79/s)

The asterisked sequoia is using the crypto-rust feature.

Methods

git-vain can use one of several methods to generate different hashes for a commit.

Note that none of these are necessary when using PGP signing. Since the signature will be different every time, the hash will also be different every time. If signing is enabled, none of these methods will be used.

increment and decrement

Increases or decreases the commit's timestamp by one second each try. This is not recommended for longer prefixes (or really at all, in the author's opinion).

counter

Appends an increasing counter to the end of the commit message (in the body).

random

Appends a random 32-character hexadecimal string to the end of the commit message (in the body).

header

Adds an additional xvain header to the commit, which contains an increasing counter. Git ignores additional headers that aren't gpgsig, so this does work and is considered valid by git fsck. In the author's opinion, it is doubtful that Git would change the way headers are parsed, but it is possible, and that would break this method (and possibly the commits created by it).

PGP performance

Signing commits drastically reduces the speed at which git-vain operates. By default, OpenSSL is used as the cryptography backend. For a moderate speedup (see table above), you can use the RustCrypto libraries as the cryptography backend instead. See the warnings below from sequoia.

As of this writing, the RustCrypto crates are not recommended for general use as they cannot offer the same security guarantees as more mature cryptographic libraries.

Some cryptographic backends can not guarantee that cryptographic operations require a constant amount of time. This may leak secret keys in some settings.

The author cannot think of a scenario in which a timing attack would matter for git-vain, but these warnings are worth acknowledging.

To use the RustCrypto libraries instead, compile with cargo build --release --no-default-features --features crypto-rust.