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format.py
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format.py
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from Crypto.Random import get_random_bytes
from Crypto.Cipher import AES
from base64 import b64encode, b64decode
from pbincli.utils import PBinCLIError
import zlib
CIPHER_ITERATION_COUNT = 100000
CIPHER_SALT_BYTES = 8
CIPHER_BLOCK_BITS = 256
CIPHER_BLOCK_BYTES = int(CIPHER_BLOCK_BITS/8)
CIPHER_TAG_BITS = int(CIPHER_BLOCK_BITS/2)
CIPHER_TAG_BYTES = int(CIPHER_TAG_BITS/8)
class Paste:
def __init__(self, debug=False):
self._version = 2
self._compression = 'zlib'
self._data = ''
self._text = ''
self._attachment = ''
self._attachment_name = ''
self._key = get_random_bytes(CIPHER_BLOCK_BYTES)
self._password = ''
self._debug = debug
def setVersion(self, version):
if self._debug: print("Set paste version to {}".format(version))
self._version = version
def setPassword(self, password):
self._password = password
def setText(self, text):
self._text = text
def setAttachment(self, path):
from pbincli.utils import check_readable, path_leaf
from mimetypes import guess_type
check_readable(path)
with open(path, 'rb') as f:
contents = f.read()
f.close()
mime = guess_type(path, strict=False)[0]
# MIME fallback
if not mime: mime = 'application/octet-stream'
if self._debug: print("Filename:\t{}\nMIME-type:\t{}".format(path_leaf(path), mime))
self._attachment = 'data:' + mime + ';base64,' + b64encode(contents).decode()
self._attachment_name = path_leaf(path)
def setCompression(self, comp):
self._compression = comp
def getText(self):
return self._text
def getAttachment(self):
return [b64decode(self._attachment.split(',', 1)[1]), self._attachment_name] \
if self._attachment \
else [False,False]
def getJSON(self):
if self._version == 2:
from pbincli.utils import json_encode
return json_encode(self._data).decode()
else:
return self._data
def loadJSON(self, data):
self._data = data
def getHash(self):
if self._version == 2:
from base58 import b58encode
return b58encode(self._key).decode()
else:
return b64encode(self._key).decode()
def setHash(self, passphrase):
if self._version == 2:
from base58 import b58decode
self._key = b58decode(passphrase)
else:
self._key = b64decode(passphrase)
def __deriveKey(self, salt):
from Crypto.Protocol.KDF import PBKDF2
from Crypto.Hash import HMAC, SHA256
# Key derivation, using PBKDF2 and SHA256 HMAC
return PBKDF2(
self._key + self._password.encode(),
salt,
dkLen = CIPHER_BLOCK_BYTES,
count = CIPHER_ITERATION_COUNT,
prf = lambda password, salt: HMAC.new(
password,
salt,
SHA256
).digest())
@classmethod
def __initializeCipher(self, key, iv, adata):
from pbincli.utils import json_encode
cipher = AES.new(key, AES.MODE_GCM, nonce=iv, mac_len=CIPHER_TAG_BYTES)
cipher.update(json_encode(adata))
return cipher
def __preparePassKey(self):
from hashlib import sha256
if self._password:
digest = sha256(self._password.encode("UTF-8")).hexdigest()
return b64encode(self._key) + digest.encode("UTF-8")
else:
return b64encode(self._key)
def __decompress(self, s):
if self._version == 2 and self._compression == 'zlib':
# decompress data
return zlib.decompress(s, -zlib.MAX_WBITS)
elif self._version == 2 and self._compression == 'none':
# nothing to do, just return original data
return s
elif self._version == 1:
return zlib.decompress(bytearray(map(lambda c:ord(c)&255, b64decode(s.encode('utf-8')).decode('utf-8'))), -zlib.MAX_WBITS)
else:
PBinCLIError('Unknown compression type provided in paste!')
def __compress(self, s):
if self._version == 2 and self._compression == 'zlib':
# using compressobj as compress doesn't let us specify wbits
# needed to get the raw stream without headers
co = zlib.compressobj(wbits=-zlib.MAX_WBITS)
return co.compress(s) + co.flush()
elif self._version == 2 and self._compression == 'none':
# nothing to do, just return original data
return s
elif self._version == 1:
co = zlib.compressobj(wbits=-zlib.MAX_WBITS)
b = co.compress(s) + co.flush()
return b64encode(''.join(map(chr, b)).encode('utf-8'))
else:
PBinCLIError('Unknown compression type provided!')
def decrypt(self):
# that is wrapper which running needed function regrading to paste version
if self._version == 2: self._decryptV2()
else: self._decryptV1()
def _decryptV2(self):
from json import loads as json_decode
iv = b64decode(self._data['adata'][0][0])
salt = b64decode(self._data['adata'][0][1])
key = self.__deriveKey(salt)
# Get compression type from received paste
self._compression = self._data['adata'][0][7]
cipher = self.__initializeCipher(key, iv, self._data['adata'])
# Cut the cipher text into message and tag
cipher_text_tag = b64decode(self._data['ct'])
cipher_text = cipher_text_tag[:-CIPHER_TAG_BYTES]
cipher_tag = cipher_text_tag[-CIPHER_TAG_BYTES:]
cipher_message = json_decode(self.__decompress(cipher.decrypt_and_verify(cipher_text, cipher_tag)).decode())
self._text = cipher_message['paste'].encode()
if 'attachment' in cipher_message and 'attachment_name' in cipher_message:
self._attachment = cipher_message['attachment']
self._attachment_name = cipher_message['attachment_name']
def _decryptV1(self):
from sjcl import SJCL
from json import loads as json_decode
password = self.__preparePassKey()
cipher_text = json_decode(self._data['data'])
if self._debug: print("Text:\t{}\n".format(cipher_text))
text = SJCL().decrypt(cipher_text, password)
if len(text):
if self._debug: print("Decoded Text:\t{}\n".format(text))
self._text = self.__decompress(text.decode())
if 'attachment' in self._data and 'attachmentname' in self._data:
cipherfile = json_decode(self._data['attachment'])
cipherfilename = json_decode(self._data['attachmentname'])
if self._debug: print("Name:\t{}\nData:\t{}".format(cipherfilename, cipherfile))
attachment = SJCL().decrypt(cipherfile, password)
attachmentname = SJCL().decrypt(cipherfilename, password)
self._attachment = self.__decompress(attachment.decode('utf-8')).decode('utf-8')
self._attachment_name = self.__decompress(attachmentname.decode('utf-8')).decode('utf-8')
def encrypt(self, formatter, burnafterreading, discussion, expiration):
# that is wrapper which running needed function regrading to paste version
self._formatter = formatter
self._burnafterreading = burnafterreading
self._discussion = discussion
self._expiration = expiration
if self._version == 2: self._encryptV2()
else: self._encryptV1()
def _encryptV2(self):
from pbincli.utils import json_encode
iv = get_random_bytes(CIPHER_TAG_BYTES)
salt = get_random_bytes(CIPHER_SALT_BYTES)
key = self.__deriveKey(salt)
# prepare encryption authenticated data and message
adata = [
[
b64encode(iv).decode(),
b64encode(salt).decode(),
CIPHER_ITERATION_COUNT,
CIPHER_BLOCK_BITS,
CIPHER_TAG_BITS,
'aes',
'gcm',
self._compression
],
self._formatter,
int(self._discussion),
int(self._burnafterreading)
]
cipher_message = {'paste':self._text}
if self._attachment:
cipher_message['attachment'] = self._attachment
cipher_message['attachment_name'] = self._attachment_name
cipher = self.__initializeCipher(key, iv, adata)
ciphertext, tag = cipher.encrypt_and_digest(self.__compress(json_encode(cipher_message)))
self._data = {'v':2,'adata':adata,'ct':b64encode(ciphertext + tag).decode(),'meta':{'expire':self._expiration}}
def _encryptV1(self):
from sjcl import SJCL
from pbincli.utils import json_encode
self._data = {'expire':self._expiration,'formatter':self._formatter,'burnafterreading':int(self._burnafterreading),'opendiscussion':int(self._discussion)}
password = self.__preparePassKey()
if self._debug: print("Password:\t{}".format(password))
# Encrypting text
cipher = SJCL().encrypt(self.__compress(self._text.encode('utf-8')), password, mode='gcm')
for k in ['salt', 'iv', 'ct']: cipher[k] = cipher[k].decode()
self._data['data'] = json_encode(cipher)
if self._attachment:
cipherfile = SJCL().encrypt(self.__compress(self._attachment.encode('utf-8')), password, mode='gcm')
for k in ['salt', 'iv', 'ct']: cipherfile[k] = cipherfile[k].decode()
cipherfilename = SJCL().encrypt(self.__compress(self._attachment_name.encode('utf-8')), password, mode='gcm')
for k in ['salt', 'iv', 'ct']: cipherfilename[k] = cipherfilename[k].decode()
self._data['attachment'] = json_encode(cipherfile)
self._data['attachmentname'] = json_encode(cipherfilename)