python: Expose the sha256() function in the utilities.
Signed-off-by: Damir Jelić <poljar@termina.org.uk>
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3 changed files with 78 additions and 10 deletions
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@ -21,7 +21,7 @@ Olm Python bindings
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| © Copyright 2015-2017 by OpenMarket Ltd
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| © Copyright 2018 by Damir Jelić
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"""
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from .utility import ed25519_verify, OlmVerifyError
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from .utility import ed25519_verify, OlmVerifyError, OlmHashError, sha256
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from .account import Account, OlmAccountError
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from .session import (
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Session,
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@ -32,6 +32,7 @@ Examples:
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# pylint: disable=redefined-builtin,unused-import
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from typing import AnyStr, Type
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from future.utils import bytes_to_native_str
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# pylint: disable=no-name-in-module
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from _libolm import ffi, lib # type: ignore
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@ -49,6 +50,10 @@ class OlmVerifyError(Exception):
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"""libolm signature verification exception."""
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class OlmHashError(Exception):
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"""libolm hash calculation exception."""
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class _Utility(object):
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# pylint: disable=too-few-public-methods
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"""libolm Utility class."""
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@ -64,12 +69,12 @@ class _Utility(object):
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track_for_finalization(cls, cls._utility, _clear_utility)
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@classmethod
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def _check_error(cls, ret):
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# type: (int) -> None
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def _check_error(cls, ret, error_class):
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# type: (int, Type) -> None
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if ret != lib.olm_error():
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return
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raise OlmVerifyError("{}".format(
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raise error_class("{}".format(
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ffi.string(lib.olm_utility_last_error(
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cls._utility)).decode("utf-8")))
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@ -84,18 +89,41 @@ class _Utility(object):
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byte_signature = to_bytearray(signature)
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try:
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cls._check_error(
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lib.olm_ed25519_verify(cls._utility, byte_key, len(byte_key),
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ffi.from_buffer(byte_message),
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len(byte_message),
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ffi.from_buffer(byte_signature),
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len(byte_signature)))
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ret = lib.olm_ed25519_verify(
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cls._utility,
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byte_key,
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len(byte_key),
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ffi.from_buffer(byte_message),
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len(byte_message),
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ffi.from_buffer(byte_signature),
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len(byte_signature)
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)
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cls._check_error(ret, OlmVerifyError)
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finally:
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# clear out copies of the message, which may be a plaintext
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if byte_message is not message:
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for i in range(0, len(byte_message)):
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byte_message[i] = 0
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@classmethod
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def _sha256(cls, input):
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# type: (Type[_Utility], AnyStr) -> str
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if not cls._utility:
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cls._allocate()
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byte_input = to_bytes(input)
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hash_length = lib.olm_sha256_length(cls._utility)
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hash = ffi.new("char[]", hash_length)
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ret = lib.olm_sha256(cls._utility, byte_input, len(byte_input),
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hash, hash_length)
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cls._check_error(ret, OlmHashError)
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return bytes_to_native_str(ffi.unpack(hash, hash_length))
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def ed25519_verify(key, message, signature):
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# type: (AnyStr, AnyStr, AnyStr) -> None
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@ -109,3 +137,14 @@ def ed25519_verify(key, message, signature):
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signature(bytes): The message signature.
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"""
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return _Utility._ed25519_verify(key, message, signature)
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def sha256(input_string):
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# type: (AnyStr) -> str
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"""Calculate the SHA-256 hash of the input and encodes it as base64.
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Args:
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input_string(str): The input for which the hash will be calculated.
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"""
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return _Utility._sha256(input_string)
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29
python/tests/utils_test.py
Normal file
29
python/tests/utils_test.py
Normal file
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@ -0,0 +1,29 @@
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import base64
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import hashlib
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from future.utils import bytes_to_native_str
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from hypothesis import given
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from hypothesis.strategies import text
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from olm import sha256
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from olm._compat import to_bytes
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class TestClass(object):
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@given(text(), text())
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def test_sha256(self, input1, input2):
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first_hash = sha256(input1)
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second_hash = sha256(input2)
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hashlib_hash = base64.b64encode(
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hashlib.sha256(to_bytes(input1)).digest()
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)
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hashlib_hash = bytes_to_native_str(hashlib_hash[:-1])
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if input1 == input2:
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assert first_hash == second_hash
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else:
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assert first_hash != second_hash
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assert hashlib_hash == first_hash
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