JWT RSA using shell script

jwt.sh

#!/bin/sh

# JWT TOKEN signing using openssl private key RS256


base64WithoutPadding()
{
  cat | openssl base64 -A | sed 's/=*$//g'
}


_sign()
{
  header="$1" && shift
  payload="$1" && shift
  secret="$1" && shift

  b64Header=$(echo -n "$header" | base64WithoutPadding)
  b64Payload=$(echo -n "$payload" | base64WithoutPadding)

  mysig="$(echo -n "$b64Header.$b64Payload" | openssl dgst -sha256 -sign $secret | base64WithoutPadding | tr '/' '_' | tr '+' '-' )"

  echo "$b64Header.$b64Payload.$mysig"
}



case $1 in
  sign)
    shift
    _sign "$@"
    ;;
  verify)
    shift
    _verify "$@"
    ;;
  *)
    echo "Invalid option." >&2 && exit 1
  ;;
esac