Android APK Signer

apksigner.sh

#   MIT License
#
#   Copyright (c) 2018 Austyn Mahoney
#
#   Permission is hereby granted, free of charge, to any person obtaining a copy
#   of this software and associated documentation files (the "Software"), to deal
#   in the Software without restriction, including without limitation the rights
#   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#   copies of the Software, and to permit persons to whom the Software is
#   furnished to do so, subject to the following conditions:
#
#   The above copyright notice and this permission notice shall be included in all
#   copies or substantial portions of the Software.
#
#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
#   SOFTWARE.

#!/usr/bin/env bash

# Store Android SDK Path
if [[ -z "${ANDROID}" ]]; then
    echo "\$ANDROID environment variable must be set to SDK Path"
    exit 1
else
    ANDROID_SDK=${ANDROID}
fi

usage () {
    cat <<HELP_USAGE

usage: $0  [--i <path>] [--o <path>] [--k <path>] [--b <version>]

-i Input APK path
-o Output APK path
-k Keystore to sign the APK with
-b Build-tools version used to sign the APK (e.g. "27.0.3")

HELP_USAGE
}

# Gets the command name without path
cmd(){ echo `basename $0`; }

# Error message
error(){
    echo "`cmd`: invalid option -- '$1'";
    echo "Try '`cmd` -h' for more information.";
    exit 1;
}

while getopts :i:o:k:b: args; do
    case "${args}" in
        i) INPUT=${OPTARG};;
        o) OUTPUT=${OPTARG};;
        k) KEYSTORE=${OPTARG};;
        b) BUILD_TOOLS_VERSION=${OPTARG};;
        :) echo error $OPTARG 1>&2;;
        \?) echo usage
    esac
done

# Build path to tools
BUILD_TOOLS="$ANDROID_SDK/build-tools/$BUILD_TOOLS_VERSION"
ZIPALIGN="$BUILD_TOOLS/zipalign" # https://developer.android.com/studio/command-line/zipalign.html
APKSIGNER="$BUILD_TOOLS/apksigner" # https://developer.android.com/studio/command-line/apksigner.html


if [ -z "${INPUT}" ] || [ -z "${OUTPUT}" ] || [ -z "${KEYSTORE}" ] || [ -z "${BUILD_TOOLS_VERSION}" ]; then
    echo "INVALID USAGE"
     usage
    exit 1
fi

if [ ! -x ${APKSIGNER} ]; then
    echo "Invalid apksigner path: \"$APKSIGNER\""
    exit 1
fi

tput rmam;
echo ""
echo " █████╗ ██████╗ ██╗  ██╗    ███████╗██╗ ██████╗ ███╗   ██╗███████╗██████╗ "
echo "██╔══██╗██╔══██╗██║ ██╔╝    ██╔════╝██║██╔════╝ ████╗  ██║██╔════╝██╔══██╗"
echo "███████║██████╔╝█████╔╝     ███████╗██║██║  ███╗██╔██╗ ██║█████╗  ██████╔╝"
echo "██╔══██║██╔═══╝ ██╔═██╗     ╚════██║██║██║   ██║██║╚██╗██║██╔══╝  ██╔══██╗"
echo "██║  ██║██║     ██║  ██╗    ███████║██║╚██████╔╝██║ ╚████║███████╗██║  ██║"
echo "╚═╝  ╚═╝╚═╝     ╚═╝  ╚═╝    ╚══════╝╚═╝ ╚═════╝ ╚═╝  ╚═══╝╚══════╝╚═╝  ╚═╝"
echo ""
tput smam

echo "-- Signing \"${INPUT}\" --"
echo "You will now be prompted for the keystore/alias password"
echo ""

# Zip Align the APK
TEMP_ZIP_ALIGN_FILE=$(mktemp)
eval "${ZIPALIGN} -p -f 4 ${INPUT} ${TEMP_ZIP_ALIGN_FILE}"
if [ $? -ne 0 ]; then
    echo "Failed to zipalign APK"
    exit 2
fi
INPUT=${TEMP_ZIP_ALIGN_FILE}

# Sign the APK
eval "${APKSIGNER} sign --ks ${KEYSTORE} --out ${OUTPUT} ${INPUT}"
if [ $? -eq 0 ]; then
    echo "-- APK signed successfully: \"$OUTPUT\" --"
else
    echo ""
    echo "Error signing APK!"
    exit 3
fi

echo ""
echo "-- Verifying APK Signature... --"
echo ""

eval "${APKSIGNER} verify ${OUTPUT}"

echo ""
echo "-- Finished apksigner verification --"
echo ""
echo "Signed APK: \"$OUTPUT\""

# Delete temp file used for zipalign
rm ${TEMP_ZIP_ALIGN_FILE}