test encryption/decryption of GPG data using generated key

testGpg.sh

#!/bin/bash
#
# testGpg.sh - performs test of GPG functionality using generated key
#

# This one-liner switches to script directory respecting symlinks
cd "$([ -L "$0" ] && dirname "$(_link="$0"; while [ -L "${_link}" ]; do _to="$(readlink "${_link}")"; _link="$([[ "${_to}" = /* ]] && echo "${_to}" || echo "$(dirname "${_link}")/${_to}")"; done; echo "${_link}")" || dirname "$0")"

# Routine to display error message and exit
abortMsg() {
	echo 1>&2 "ERROR: $*"
	exit 1
}

# Debug Level setting
_debugLevel="--debug-level expert"
#_debugLevel=""

# Validate argument
_privateKeyFile="$1"
[[ -f "${_privateKeyFile}" ]] ||
	abortMsg "required argument: PRIVATE-KEY-FILE"

# Temporary directory
_tempDir="$(mktemp -d)"

# Cleanup routine
function _performCleanup() {
	ps -ef | fgrep gpg-agent | fgrep -- "${_tempDir}" | awk '{print $2}' | xargs kill
	#rm -rf "${_tempDir}"
}
trap _performCleanup EXIT

# Write passphrase
_passPhraseFile="${_tempDir}/passPhraseFile"
uuidgen >"${_passPhraseFile}" || abortMsg "failed writing passphrase"

# Print version
echo "INFO: Dumping GPG version"
echo ""
gpg --version || abortMsg "failed dumping GPG version"
echo ""
echo "SUCCESS: Dumped GPG version"

# Generate random test data
echo "INFO: Generating random test data"
_randomTestData="${_tempDir}/randomTestData.dat"
dd if=/dev/urandom of="${_randomTestData}" bs=1024 count=64 ||
	abortMsg "Generating random test data failed"
echo "SUCCESS: Random test data generation complete"
_encryptedData="${_tempDir}/randomTestData.encrypted"
_decryptedData="${_tempDir}/randomTestData.decrypted"

# Public home (outbound)
_publicHome="${_tempDir}/public"
mkdir -p "${_publicHome}" || abortMsg "creating directory '${_publicHome}' failed"
chmod 700 "${_publicHome}" || abortMsg "setting permissions on directory '${_publicHome}' failed"

# Private home (inbound)
_privateHome="${_tempDir}/private"
mkdir -p "${_privateHome}" || abortMsg "creating directory '${_privateHome}' failed"
chmod 700 "${_privateHome}" || abortMsg "setting permissions on directory '${_privateHome}' failed"

# Start GPG agent
echo "INFO: Starting GPG agent"
gpg-agent ${_debugLevel} --homedir "${_privateHome}" --daemon
echo "DONE: Started GPG agent"

# Import private key into GPG
echo "INFO: Importing private key into GPG"
gpg --batch --pinentry-mode loopback --passphrase-file "${_passPhraseFile}" \
	--homedir "${_privateHome}" --import "${_privateKeyFile}" ||
		abortMsg "gpg private key import failed"
echo "SUCCESS: Private key imported into GPG"

# Set key trust to ultimate
echo "INFO: Configure GPG to fully trust private key"
gpg --homedir "${_privateHome}" --list-keys --with-colons |
	egrep ^fpr: |
	cut -d: -f10 |
	sed -e 's/$/:6:/' |
	gpg --homedir "${_privateHome}" --import-ownertrust ||
		abortMsg "GPG key trust failed"
echo "SUCCESS: Configured GPG to fully trust private key"

# Export public key
echo "INFO: Exporting public key"
_privateKeyId="$(gpg --homedir "${_privateHome}" --list-keys | egrep ^uid | awk '{print$3}')"
[ -n "${_privateKeyId}" ] || abortMsg "Could not determine ID of private key"
gpg --homedir "${_privateHome}" --output "${_tempDir}/publicKey.out" --export "${_privateKeyId}" ||
	abortMsg "public key export failed"
echo "SUCCESS: Public key exported from GPG"

# Import public key into GPG public home
echo "INFO: Importing public key into GPG"
gpg --homedir "${_publicHome}" --import "${_tempDir}/publicKey.out" ||
	abortMsg "gpg public key import failed"
echo "SUCCESS: Public key imported into GPG"

# Set key trust to ultimate
echo "INFO: Configure GPG to fully trust public key"
gpg --homedir "${_publicHome}" --list-keys --with-colons |
	egrep ^fpr: |
	cut -d: -f10 |
	sed -e 's/$/:6:/' |
	gpg --homedir "${_publicHome}" --import-ownertrust ||
		abortMsg "GPG key trust failed"
echo "SUCCESS: Configured GPG to fully trust public key"

# Encrypt the random test data
echo "INFO: About to encrypt random data using GPG"
cat "${_randomTestData}" |
	gpg --batch --homedir "${_publicHome}" --batch --encrypt \
		-r "${_privateKeyId}" --cipher-algo AES256 --compress-algo none -o "${_encryptedData}" ||
	abortMsg "encryption of test data fails"
echo "SUCCESS: Encrypted random data using GPG"

# Decrypt the data
gpg ${_debugLevel} --batch --pinentry-mode loopback --passphrase-file "${_passPhraseFile}" \
	--homedir "${_privateHome}" --output "${_decryptedData}" --decrypt "${_encryptedData}" \
		|| abortMsg "decryption failed"