hmac-sha1

#!/bin/sh

set -eu

. ./hmac-sha1.sh

prog=$0

usage() {
  cat << HERE
Usage: $prog [--binary | --base64] [<key-file>]

Example:

$ printf '%s' value | $prog <(printf '%s' secret_key)
b75db159dc00e1e84e251a1ea6176359e7427901

$ printf '%s' value | KEY=secret_key $prog
b75db159dc00e1e84e251a1ea6176359e7427901

$ printf '%s' value | ./hmac-sha1 --binary <(printf '%s' secret_key) | base64
t12xWdwA4ehOJRoephdjWedCeQE=

$ printf '%s' value | ./hmac-sha1 --base64 <(printf '%s' secret_key)
t12xWdwA4ehOJRoephdjWedCeQE=

HERE
}

if [ $# -eq 0 ] && [ "${KEY:-}" = "" ]; then
  usage
  exit 1
fi

func="hmac_sha1"
case ${1:-} in
  -h | --help) usage && exit 0 ;;
  --binary) func="hmac_sha1_binary" && shift ;;
  --base64) func="hmac_sha1_base64" && shift ;;
  -*) echo "Unknown option $1" >&2 && exit 1 ;;
esac

if [ $# -eq 0 ]; then
  key="${KEY:?}"
else
  key=$(cat "$1" && echo _)
  key=${key%_}
fi

msg=$(cat && echo _)
msg=${msg%_}

"$func" "$key" "$msg"