Bash utility to encrypt/decrypt strings using GPG and Base64 with passphrase-based symmetric encryption.

secure

#!/bin/bash

# Usage function
usage() {
    echo "Usage:"
    echo "  $0 --encrypt --value <string> --passphrase <passphrase>"
    echo "  $0 --decrypt --value <encrypted_string> --passphrase <passphrase>"
    exit 1
}

# Parse arguments
MODE=""
VALUE=""
PASSPHRASE=""

while [[ "$#" -gt 0 ]]; do
    case "$1" in
        --encrypt) MODE="encrypt" ;;
        --decrypt) MODE="decrypt" ;;
        --value) VALUE="$2"; shift ;;
        --passphrase) PASSPHRASE="$2"; shift ;;
        *) echo "Unknown parameter passed: $1"; usage ;;
    esac
    shift
done

# Validate input
if [[ -z "$MODE" || -z "$VALUE" || -z "$PASSPHRASE" ]]; then
    usage
fi

# Perform encryption
if [[ "$MODE" == "encrypt" ]]; then
    echo -n "$VALUE" | gpg --symmetric --quiet --batch --yes \
        --passphrase "$PASSPHRASE" --output - | base64 --wrap=0

# Perform decryption
elif [[ "$MODE" == "decrypt" ]]; then
  echo -n "$VALUE" | base64 --decode | gpg --decrypt --quiet --batch \
        --yes --passphrase "$PASSPHRASE"

else
    echo "Invalid mode specified."
    usage
fi