Simple Bash TOTP client

totp.sh

#!/bin/bash

# Copyright (c) 2018, info AT markusholtermann DOT eu
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#     * Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#     * Neither the name of the <organization> nor the
#       names of its contributors may be used to endorse or promote products
#       derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

set -e
set -o pipefail

SOURCE_DIR=~/.config/2fa

function init() {
    mkdir -p $SOURCE_DIR
    chmod 0700 $SOURCE_DIR

    if ! hash gpg 2>/dev/null ; then
        echo "Please ensure that GnuPG is installed!"
        exit 1
    fi
    if ! hash oathtool 2>/dev/null ; then
        echo "Please ensure that oathtool is installed!"
        exit 2
    fi
}

function add_key() {
    echo "Adding a new key"
    if [ "x$1" != "x" ] ; then
        identifier=$1
    else
        echo "What's the identifier?"
        read -r identifier
    fi
    echo "What's the secret?"
    read -r secret
    echo "$secret" | gpg --quiet --symmetric --out "$SOURCE_DIR/$identifier"
}

function get_totp() {
    if [ "x$1" != "x" ] ; then
        identifier=$1
    else
        echo "What's the identifier?"
        read -r identifier
    fi
    secret="$(gpg --quiet < "$SOURCE_DIR/$identifier")"
    oathtool --base32 --totp "$secret"
}

function list() {
    ls -1 "$SOURCE_DIR"
}

function help() {
    echo "Setup a new TOTP account or generate a new TOTP token from an existing account."
    echo
    echo "Usage: totp.sh [--add|--list|--totp] [IDENTIFIER]"
    echo
    echo -e "--add     Will ask for an identifier (i.e. 'google', 'slack', ...) and\\n" \
            "         then for the secret provided by the service provider."
    echo -e "--list    Will list all available identifiers."
    echo -e "--totp    Will ask for an identifier (i.e. 'google', 'slack', ...) and\\n" \
            "         then return the TOTP token."
}

init

case $1 in
    --add)
        add_key "$2"
        ;;
    --list)
        list
        ;;
    --totp)
        get_totp "$2"
        ;;
    *)
        help
esac