PM : decrypt attachments

PMDecryptAttachments.py

import pgpy
import pandas
import sqlite3
from Crypto.cipher import AES
import os
from base64 import b64decode
import plistllib
import ccl_bplist


IVsize = 16

# Decrypt values using main key and AES_CTR
def decryptWithMainKey(encrypted, mainKey):
    iv = encrypted[:IVsize]
    cipher = AES.new(mainKey, AES.MODE_CTR, initial_value=iv, nonce=b'')
    return cipher.decrypt(encrypted[IVsize:])

# Decrypt an attachment
def decrypt_attachment(proton_path, out_path, key, pwdKey, keyPacket, encfilename, decfilename):
	att = None
	for r, _, f in os.walk(proton_path):
		for file in f:
			if encfilename in file:
				att=os.path.join(r,file)
				break
	if att:
		with key.unlock(pwdKey):
			assert key.is_unlocked
			with open(att, 'rb') as attfh:
				buf = b64decode(keyPacket)
				buf += attfh.read()
				att_from_blob = pgpy.PGPMessage.from_blob(buf)
				decatt = key.decrypt(att_from_blob).message
				with open(os.path.join(out_path,decfilename),'wb') as outatt:
					outatt.write(decatt)
				return decfilename
	return None

# Decrypt table Attachments and attachment itself
def decrypt_records_attachments(row, mainKey, proton_path, out_path, key, pwdKey):
	if row['ZFILENAME']:
		row['ZFILENAME'] = decryptWithMainKey(row['ZFILENAME'], mainKey)
	if row['ZHEADERINFO']:
		row['ZHEADERINFO'] = decryptWithMainKey(row['ZHEADERINFO'], mainKey)
	if row['ZMIMETYPE']:
		row['ZMIMETYPE'] = decryptWithMainKey(row['ZMIMETYPE'], mainKey)
	if row['ZFILENAME']:
		filename = plistlib.loads(row['ZFILENAME'])[0]
	if row['ZLOCALURL']:
		encfilename = plistlib.loads(row['ZLOCALURL'])['$objects'][2].split('/')[-1]
		row['decrypted_file'] = decrypt_attachment(proton_path, out_path, key, pwdKey, row['ZKEYPACKET'], encfilename, filename)
		row['content-type'] = plistlib.loads(row['ZMIMETYPE'])[0]

	return row


def main():
  proton_path = 'path/to/extraction'
  out_path = 'path/to/output'
  mainKey = 'decrypted with PMPinProtection or gathered directly from keychain'

  with open('group.ch.protonmail.protonmail.plist','rb') as p :
    prefplist = plistlib.load(p)

  enc_val = prefplist['authKeychainStoreKeyProtectedWithMainKey']
  dec_val = decryptWithMainKey(enc_val, mainKey)

  keychainStorePlist1 = ccl_bplist.load(BytesIO(dec_val))
  keychainStorePlist = ccl_bplist.load(BytesIO(keychainStorePlist1[0]))
  keychainStore = ccl_bplist.deserialise_NsKeyedArchiver(keychainStorePlist, parse_whole_structure=True)
  privateKeyCoderKey = keychainStore['root']['NS.objects'][0]['privateKeyCoderKey']

  key, _ = pgpy.PGPKey.from_blob(privateKeyCoderKey)
  pwdKey = keychainStore['root']['NS.objects'][0]['AuthCredential.Password']
  
  with sqlite3.connect('ProtonMail.sqlite') as db:
    df = pandas.read_sql_query("""
        SELECT
          *
        FROM
          ZATTACHMENT

        """,db)
    df = df.apply(decrypt_records_attachments, args=(mainKey, proton_path, out_path, key, pwdKey, ), axis=1)