#!/usr/bin/python

“““
Python?wrapper?of?the?botan?crypto?library
https://botan.randombit.net

（C）?201520172018?Jack?Lloyd
（C）?2015?Uri??Blumenthal?（extensions?and?patches）

Botan?is?released?under?the?Simplified?BSD?License?（see?license.txt）

This?module?uses?the?ctypes?module?and?is?usable?by?programs?running
under?at?least?CPython?2.7?CPython?3.x?and?PyPy

It?uses?botan‘s?ffi?module?which?exposes?a?C?API.?This?version?of?the
module?requires?FFI?API?version?20180713?which?was?introduced?in
Botan?2.8

“““

from?ctypes?import?CDLL?POINTER?byref?create_string_buffer?\
????c_void_p?c_size_t?c_uint8?c_uint32?c_uint64?c_int?c_char?c_char_p

from?sys?import?version_info
from?time?import?strptime?mktime
from?binascii?import?hexlify
from?datetime?import?datetime

BOTAN_FFI_VERSION?=?20180713

#
#?base?exception?for?all?exceptions?raised?from?this?module
#
class?BotanException（Exception）:

????def?__init__（self?message?rc=0）:

????????self.__rc?=?rc

????????if?rc?==?0:
????????????super（BotanException?self）.__init__（message）
????????else:
????????????descr?=?botan.botan_error_description（rc）.decode（‘ascii‘）
????????????super（BotanException?self）.__init__（“%s:?%d?（%s）“?%?（message?rc?descr））

????def?error_code（self）:
????????return?self.__rc

#
#?Module?initialization
#

def?load_botan_dll（expected_version）:

????possible_dll_names?=?[‘libbotan-2.dylib‘?‘libbotan-2.so‘]?+?\
?????????????????????????[‘libbotan-2.so.%d‘?%?（v）?for?v?in?reversed（range（8?16））]

????for?dll_name?in?possible_dll_names:
????????try:
????????????dll?=?CDLL（dll_name）
????????????dll.botan_ffi_supports_api.argtypes?=?[c_uint32]
????????????dll.botan_ffi_supports_api.restype?=?c_int
????????????if?dll.botan_ffi_supports_api（expected_version）?==?0:
????????????????return?dll
????????except?OSError:
????????????pass

????return?None

botan?=?load_botan_dll（BOTAN_FFI_VERSION）?#?pylint:?disable=invalid-name

if?botan?is?None:
????raise?BotanException（“Could?not?find?a?usable?Botan?shared?object?library“）

#
#?ctypes?function?prototypes
#
def?errcheck_for（fn_name）:
????def?errcheck（rc?_func?_args）:
????????#?No?idea?what?to?do?if?return?value?isn‘t?an?int?just?return?it
????????if?not?isinstance（rc?int）:
????????????return?rc

????????if?rc?>=?0:
????????????return?rc
????????if?rc?==?-10:?#?insufficient?buffer?space?pass?up?to?caller
????????????return?rc
????????raise?BotanException（‘%s?failed‘?%?（fn_name）?rc）
????return?errcheck

botan.botan_version_string.argtypes?=?[]
botan.botan_version_string.restype?=?c_char_p

botan.botan_error_description.argtypes?=?[c_int]
botan.botan_error_description.restype?=?c_char_p

#?RNG
botan.botan_rng_init.argtypes?=?[c_void_p?c_char_p]
botan.botan_rng_init.errcheck?=?errcheck_for（‘botan_rng_init‘）

botan.botan_rng_destroy.argtypes?=?[c_void_p]
botan.botan_rng_destroy.errcheck?=?errcheck_for（‘botan_rng_destroy‘）

botan.botan_rng_reseed.argtypes?=?[c_void_p?c_size_t]
botan.botan_rng_reseed.errcheck?=?errcheck_for（‘bota