app.py

import os
import io
import wave
import struct
import logging
import hashlib
from flask import Flask, render_template, request, send_file, jsonify
from werkzeug.utils import secure_filename
from pydub import AudioSegment
import magic

app = Flask(__name__)

logging.basicConfig(level=logging.DEBUG)
logger = app.logger

UPLOAD_FOLDER = '/tmp'
ALLOWED_EXTENSIONS = {'png', 'jpg', 'jpeg', 'gif', 'mp3', 'wav', 'txt', 'pdf', 'docx'}

app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/process', methods=['POST'])
def process_file():
    logger.info("Processing file request received")
    if 'file' not in request.files:
        logger.error("No file part in the request")
        return jsonify({'error': 'No file part'}), 400
    file = request.files['file']
    if file.filename == '':
        logger.error("No selected file")
        return jsonify({'error': 'No selected file'}), 400
    if file and allowed_file(file.filename):
        filename = secure_filename(file.filename)
        filepath = os.path.join(app.config['UPLOAD_FOLDER'], filename)
        file.save(filepath)
        logger.info(f"File saved: {filepath}")

        factor = int(request.form['factor'])
        is_decrypting = filename.lower().endswith('.mp3')
        logger.info(f"Processing file: {'decrypting' if is_decrypting else 'encrypting'} with factor {factor}")

        try:
            if is_decrypting:
                output, output_filename, mimetype = decrypt_file(filepath, factor)
            else:
                output, output_filename, mimetype = encrypt_file(filepath, factor)

            logger.info(f"File processed successfully. Output size: {len(output)} bytes")
            os.remove(filepath)
            logger.info(f"Temporary file removed: {filepath}")

            return send_file(
                io.BytesIO(output),
                mimetype=mimetype,
                as_attachment=True,
                download_name=output_filename
            )
        except Exception as e:
            logger.error(f"Error processing file: {str(e)}")
            os.remove(filepath)
            return jsonify({'error': str(e)}), 500

    logger.error("Invalid file type")
    return jsonify({'error': 'Invalid file type'}), 400

def calculate_checksum(data):
    return hashlib.md5(data).hexdigest()

def encrypt_file(filepath, factor):
    logger.info(f"Encrypting file: {filepath}")
    with open(filepath, 'rb') as file:
        data = file.read()
    
    # Calculate checksum
    checksum = calculate_checksum(data)
    
    # Convert data to audio samples
    samples = [int(byte * factor) for byte in data]
    
    # Add checksum to the beginning of the samples
    checksum_samples = [ord(byte) for byte in checksum.encode('ascii')]
    samples = checksum_samples + samples
    
    # Create WAV file
    wav_output = io.BytesIO()
    with wave.open(wav_output, 'wb') as wav_file:
        wav_file.setnchannels(1)
        wav_file.setsampwidth(2)
        wav_file.setframerate(44100)
        wav_file.writeframes(struct.pack(f'{len(samples)}h', *samples))
    
    # Convert WAV to MP3
    wav_output.seek(0)
    audio = AudioSegment.from_wav(wav_output)
    mp3_output = io.BytesIO()
    audio.export(mp3_output, format="mp3")
    
    logger.info(f"Encryption complete. Output size: {mp3_output.getbuffer().nbytes} bytes")
    return mp3_output.getvalue(), 'encrypted.mp3', 'audio/mpeg'

def decrypt_file(filepath, factor):
    logger.info(f"Decrypting file: {filepath}")
    
    # Convert MP3 to WAV
    audio = AudioSegment.from_mp3(filepath)
    wav_output = io.BytesIO()
    audio.export(wav_output, format="wav")
    wav_output.seek(0)
    
    with wave.open(wav_output, 'rb') as wav_file:
        params = wav_file.getparams()
        frames = wav_file.readframes(wav_file.getnframes())
    
    samples = struct.unpack(f'{len(frames)//2}h', frames)
    
    # Extract checksum
    checksum = ''.join(chr(sample // factor) for sample in samples[:32])
    samples = samples[32:]
    
    # Decrypt data
    decrypted_bytes = bytearray()
    for sample in samples:
        byte_value = int(round(sample / factor))
        decrypted_bytes.append(max(0, min(byte_value, 255)))
    
    decrypted_data = bytes(decrypted_bytes)
    
    # Verify checksum
    if calculate_checksum(decrypted_data) != checksum:
        raise ValueError("Checksum verification failed. The file may be corrupted or the wrong factor was used.")
    
    # Detect original file type
    mime = magic.Magic(mime=True)
    file_type = mime.from_buffer(decrypted_data)
    file_extension = file_type.split('/')[-1]
    
    logger.info(f"Decryption complete. Output size: {len(decrypted_data)} bytes")
    return decrypted_data, f'decrypted_file.{file_extension}', file_type

if __name__ == '__main__':
    app.run(debug=True)