Send a small ammount of money via bitcoin after making a git commit so that the blockchain can be used to verify the time at which the commit was made (https://www.btproof.com/)

post_commit_btproof.sh

#!/bin/bash

# What this does:
#
# This is an untested (I have no idea what the syntax is for bitcoind, so this probably doesn't actually work;
# it's just an idea) post-commit hook for sending a bitcoin transaction. This allows one to use the bitcoin
# blockchain for trusted timestamping of git commits. This might be useful if you expect a bogus copyright claim,
# or want to make sure you have proof that you started a project before working for a company or going to a school
# that likes to seize intellectual property from their employees and claim it was developed on their dime.
#
# For more information: https://www.btproof.com/

VERSION_BYTE='00'

BT_USER=$(git config bt.user.name || echo 'user')
BT_HOST=$(git config bt.server.host || echo '127.0.0.1')
BT_PORT=$(git config bt.server.port || echo '8332')
BT_SEND=$(git config bt.amount || echo '0.00000001')
BT_ADDR=$(hash_to_address)

# Base58 copied from some script online. Lost the link; sorry.
base58=({1..9} {A..H} {J..N} {P..Z} {a..k} {m..z})
EncodeBase58() {
    # 58 =0x3A
    bc <<<"ibase=16; n=${1^^}; while(n>0) { n%3A ; n/=3A }" |
    tac |
    while read n
    do echo -n ${base58[n]}
    done
}

hash_to_address() {
  hash=${VERSION_BYTE}$(git rev-parse HEAD | openssl rmd160 | cut -d ' ' -f 2)
  checksum=$(echo ${hash} | sha256sum | cut -d ' ' -f 1 | sha256sum | cut -d ' ' -f 1)
  checksum=${checksum:0:8}

  echo $(EncodeBase58 "${hash}${checksum}")
}

curl --user $BT_USER --data-binary \
  '{"jsonrpc": "1.0", "id":"gitbtproof", "method": "sendtoaddress", "params": ["'${BT_ADDR}'" "'${BT_SEND}'"] }' \
  -H 'content-type: text/plain;' http://$BT_HOST:$BT_PORT/