UNICODE Password Utility

#!/bin/bash
# -----------------------------------------------------------------------------
# Interactive File Protector Script (Encryption/Decryption)
# Dependencies: openssl (with PBKDF2 support), shred (optional secure delete)
# -----------------------------------------------------------------------------
ENCRYPT_EXT=".enc"
CIPHER_METHOD="aes-256-cbc"

error_message() { echo -e "\n\033[31m[ERROR]\033[0m $1"; }
get_password() { read -rsp "Enter password: " PASSWORD; echo ""; }

encrypt_file() {
    echo -e "\n--- File Encryption ---"
    read -rp "Filename to encrypt: " INPUT_FILE
    [ ! -f "$INPUT_FILE" ] && error_message "File not found." && return 1
    OUTPUT_FILE="${INPUT_FILE}${ENCRYPT_EXT}"
    get_password
    if openssl enc -"$CIPHER_METHOD" -salt -pbkdf2 -in "$INPUT_FILE" -out "$OUTPUT_FILE" -k "$PASSWORD"; then
        echo -e "\033[32m[SUCCESS]\033[0m Encrypted to $OUTPUT_FILE"
        read -rp "Securely delete original? (y/N): " del
        [[ "$del" =~ ^[Yy]$ ]] && command -v shred &>/dev/null && shred -u "$INPUT_FILE" || rm -f "$INPUT_FILE"
    else
        error_message "Encryption failed."
    fi
}

decrypt_file() {
    echo -e "\n--- File Decryption ---"
    read -rp "Encrypted filename: " INPUT_FILE
    [ ! -f "$INPUT_FILE" ] && error_message "File not found." && return 1
    OUTPUT_FILE="${INPUT_FILE%$ENCRYPT_EXT}"
    [ "$OUTPUT_FILE" == "$INPUT_FILE" ] && read -rp "Output filename: " OUTPUT_FILE
    [ -f "$OUTPUT_FILE" ] && error_message "Output exists. Abort." && return 1
    get_password
    openssl enc -d -"$CIPHER_METHOD" -pbkdf2 -in "$INPUT_FILE" -out "$OUTPUT_FILE" -k "$PASSWORD" && \
        echo -e "\033[32m[SUCCESS]\033[0m Decrypted to $OUTPUT_FILE" || error_message "Wrong password or corrupt file."
}

main_menu() {
    echo "========================================="
    echo "        File Protection Utility          "
    echo "========================================="
    echo "1. Encrypt a File"
    echo "2. Decrypt a File"
    echo "3. Exit"
    read -rp "Choice (1-3): " CHOICE
    case "$CHOICE" in
        1) encrypt_file ; main_menu ;;
        2) decrypt_file ; main_menu ;;
        3) echo "Goodbye." ; exit 0 ;;
        *) error_message "Invalid option." ; main_menu ;;
    esac
}
main_menu