118 lines
3.2 KiB
Python
118 lines
3.2 KiB
Python
|
#!/usr/bin/env python3
|
||
|
|
# -*- coding: utf-8 -*-
|
||
|
|
|
||
|
|
'''
|
||
|
|
Use my own small RSA code so we don't have to include the huge
|
||
|
|
python3-rsa just for these small bits.
|
||
|
|
The original code used blinding and this one doesn't,
|
||
|
|
but we don't really care about side-channel attacks ...
|
||
|
|
'''
|
||
|
|
|
||
|
|
import sys
|
||
|
|
|
||
|
|
try:
|
||
|
|
from Cryptodome.PublicKey import RSA
|
||
|
|
except ImportError:
|
||
|
|
# Some distros still ship this as Crypto
|
||
|
|
from Crypto.PublicKey import RSA
|
||
|
|
|
||
|
|
class CustomRSA:
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def encrypt_for_adobe_signature(signing_key, message):
|
||
|
|
key = RSA.importKey(signing_key)
|
||
|
|
keylen = CustomRSA.byte_size(key.n)
|
||
|
|
padded = CustomRSA.pad_message(message, keylen)
|
||
|
|
payload = CustomRSA.transform_bytes2int(padded)
|
||
|
|
encrypted = CustomRSA.normal_encrypt(key, payload)
|
||
|
|
block = CustomRSA.transform_int2bytes(encrypted, keylen)
|
||
|
|
return bytearray(block)
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def byte_size(number):
|
||
|
|
# type: (int) -> int
|
||
|
|
return (number.bit_length() + 7) // 8
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def pad_message(message, target_len):
|
||
|
|
# type: (bytes, int) -> bytes
|
||
|
|
|
||
|
|
# Padding always uses 0xFF
|
||
|
|
# Returns: 00 01 PADDING 00 MESSAGE
|
||
|
|
|
||
|
|
max_message_length = target_len - 11
|
||
|
|
message_length = len(message)
|
||
|
|
|
||
|
|
if message_length > max_message_length:
|
||
|
|
raise OverflowError("Message too long, has %d bytes but only space for %d" % (message_length, max_message_length))
|
||
|
|
|
||
|
|
padding_len = target_len - message_length - 3
|
||
|
|
|
||
|
|
ret = bytearray(b"".join([b"\x00\x01", padding_len * b"\xff", b"\x00"]))
|
||
|
|
ret.extend(bytes(message))
|
||
|
|
|
||
|
|
return ret
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def normal_encrypt(key, message):
|
||
|
|
|
||
|
|
if message < 0 or message > key.n:
|
||
|
|
raise ValueError("Invalid message")
|
||
|
|
|
||
|
|
encrypted = pow(message, key.d, key.n)
|
||
|
|
return encrypted
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def py2_int_to_bytes(value, length, big_endian = True):
|
||
|
|
result = []
|
||
|
|
|
||
|
|
for i in range(0, length):
|
||
|
|
result.append(value >> (i * 8) & 0xff)
|
||
|
|
|
||
|
|
if big_endian:
|
||
|
|
result.reverse()
|
||
|
|
|
||
|
|
return result
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def py2_bytes_to_int(bytes, big_endian = True):
|
||
|
|
# type: (bytes, bool) -> int
|
||
|
|
|
||
|
|
my_bytes = bytes
|
||
|
|
if not big_endian:
|
||
|
|
my_bytes.reverse()
|
||
|
|
|
||
|
|
result = 0
|
||
|
|
for b in my_bytes:
|
||
|
|
result = result * 256 + int(b)
|
||
|
|
|
||
|
|
return result
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def transform_bytes2int(raw_bytes):
|
||
|
|
# type: (bytes) -> int
|
||
|
|
|
||
|
|
if sys.version_info[0] >= 3:
|
||
|
|
return int.from_bytes(raw_bytes, "big", signed=False)
|
||
|
|
|
||
|
|
return CustomRSA.py2_bytes_to_int(raw_bytes, True)
|
||
|
|
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def transform_int2bytes(number, fill_size = 0):
|
||
|
|
# type: (int, int) -> bytes
|
||
|
|
|
||
|
|
if number < 0:
|
||
|
|
raise ValueError("Negative number")
|
||
|
|
|
||
|
|
size = None
|
||
|
|
|
||
|
|
if fill_size > 0:
|
||
|
|
size = fill_size
|
||
|
|
else:
|
||
|
|
size = max(1, CustomRSA.byte_size(number))
|
||
|
|
|
||
|
|
if sys.version_info[0] >= 3:
|
||
|
|
return number.to_bytes(size, "big")
|
||
|
|
|
||
|
|
return CustomRSA.py2_int_to_bytes(number, size, True)
|